Possible karyotypes of Down syndrome. Down syndrome karyotype

Date: 11.11.2021

The number of chromosomal diseases is huge and one of them is Patau syndrome. The karyotype of a patient with a similar diagnosis is changed, which is reflected in the work of the whole organism. Pathology affects the structure of the skeleton, the work of the nervous, excretory, reproductive and cardiovascular systems.

Many parents today are interested in any additional information about this pathology. What is Patau Syndrome? The karyotype and phenotypic characteristics, methods of diagnosis and treatment, symptoms and causes are all interesting points. These issues are worth exploring in more detail.

Patau syndrome: karyotype and general information

To begin with, it's worth understanding the general data. What is Patau Syndrome and how does it develop? Chromosomes with such a pathology do not diverge during the formation of gametes or zygotes, which leads to a mass of disorders in the process of embryonic development.

Patau syndrome is a congenital disease that is associated with trisomy of the 13th pair of chromosomes - the child receives the karyotype formula in this case may look like this: 47, XX, 13 + (for girls), 47, XY, 13 + (for boys). This is an extremely dangerous and serious disease, which is accompanied by the formation of multiple developmental defects - they are often incompatible with life, so the child dies while still in the womb.

Brief historical background

The symptoms of this pathology were first described in 1657 in the works of the Danish scientist Erasmus Bartholin. Nevertheless, the chromosomal nature of the disease was proved by Dr. Klaus Patau in 1960 (the syndrome was named in his honor).

Cases of such congenital abnormalities have been described by scientists who have studied the tribes of the Pacific Islands. It is believed that the increased frequency of chromosomal mutations in this geographic area was caused by radiation damage following nuclear weapons tests.

The reasons for the development of the disease

As already mentioned, Patau syndrome is characterized by trisomy of the thirteenth pair of chromosomes. Moreover, in most cases (according to statistics, in 80%) there is a nondisjunction of the thirteenth chromosome in the process of meiosis. Most often, the child receives a full pair of chromosomes from the mother. Sometimes it takes place in which the embryo already receives an additional copy of the genes.

It has been proven that a genetic breakdown can occur during the formation of a gamete or later during the formation of a zygote.

To date, the reasons for the appearance of the mutation have not been established - it is believed that it occurs absolutely by chance. The role of infections, bad habits, somatic diseases of the mother in the development of this pathology in the fetus is also unknown.

Types of pathology

To date, there are several forms of this disease.

Simple form. In this case, violations occur in the early stages of embryo development. Moreover, each cell of the body contains an extra chromosome in the thirteenth pair.
Mosaic shape. Similar changes occur at later stages of fetal development. Moreover, some organs consist only of healthy cells, while other tissues and organs contain pathologically altered cells. With this form of the disease, symptoms may be less pronounced.

Are there risk factors? What can provoke the appearance of a mutation?

Patau syndrome develops spontaneously and, alas, it is impossible to prevent it. Nevertheless, scientists have identified several unfavorable factors.

It is believed that the risk of developing such a pathology increases if the mother lives in an area with a poor environmental situation.
As already mentioned, radiation exposure plays a role in the appearance of spontaneous chromosomal mutations.
It has also been noticed that the likelihood of the appearance of various chromosomal and genetic mutations increases in the case of late pregnancy (mother over 45 years old).
Risk factors include the presence of hereditary diseases in previous generations of parents.
It has been proven that cases of genetic and chromosomal mutations are more frequent when it comes to marriages between close relatives.

Symptoms of pathology during pregnancy

As already mentioned, the karyotype formula in Patau syndrome has been changed, but it is impossible to detect this without special tests. However, this pregnancy is often accompanied by polyhydramnios. According to statistics, the time for bearing the fetus is also reduced - an average of about 38.5 weeks. It is worth noting that with such a pathology, pregnancy is often terminated. There is a high risk of stillbirth.

Patau syndrome: photos and distinctive signs

Children with this mutation have a number of special phenotypic characteristics. To begin with, it is worth saying that babies give birth on time, but with low weight - prenatal malnutrition takes place (the weight of a full-term baby with a similar diagnosis rarely exceeds 2500 g). The very process of childbirth is also often associated with complications, in particular, newborn asphyxiation.

A child with a chromosomal mutation has a number of congenital deformities of the cerebral and facial parts of the skull. There is microcephaly - the baby's head circumference is much less than normal. In children with Patau syndrome, the forehead is often low and sloping, the bridge of the nose is flat and sunken, and the palpebral fissures are narrow. The auricles are usually deformed and set low.

A typical symptom is the presence of double-sided clefts of the face, in particular, the so-called cleft palate (pathology is accompanied by the splitting of tissues of the soft and hard palate, and the nasal and oral cavities are interconnected), as well as "cleft lip" (cleft lip). The doctor may suspect the presence of this chromosomal mutation already in the first few after the birth of the child.

Pathology from other organ systems

What other disorders are accompanied by Patau syndrome? Signs of facial deformities are by no means the only ones. The disease affects the work of almost all organ systems, causing severe congenital defects.

Many children have disorders of the central nervous system and visual analyzers. Possible hydrocephalus, hyloprocephalus, dysginesia of the corpus callosum, as well as the formation of spinal hernias. Possible complications include deafness, congenital forms of cataracts, retinal dysplasia, a decrease in the number of axons in the structure of the optic nerve, which leads to serious visual impairment.
Possible including open aortic duct, aortic coarctation, ventricular and atrial septal defects.
Many babies are born with kidney defects. For example, patients are diagnosed with hydronephrosis, polycystic disease, as well as a pathology called "horseshoe kidney".
Abnormal changes in the digestive tract are possible. Their list includes the formation of Meckel diverticula, cystic neoplasms in the tissues of the pancreas, incomplete bowel rotation.
The mutation also affects the organs of the reproductive system. In boys, there may be a delay in the descent of the testicles into the scrotum (cryptorchymal), as well as a displacement of the external opening of the urethra. In newborn girls, hypertrophy of the labia and clitoris, the formation of a bicornuate uterus, or even the formation of two separate uterus and vaginas are often observed.
Pathology affects not only the bones of the skull, but also other structures of the skeleton. For example, children with Patau syndrome often have polydactyly (extra toes on the feet and hands) and syndactyly (fusion of fingers).
All children with this disease suffer from severe forms of physical and mental retardation.

As you can see, this chromosomal pathology has dangerous and serious consequences, so the prognosis for children is unfavorable.

Diagnostic measures

Is it possible during intrauterine development to identify a disease such as Patau syndrome? Diagnostics at this stage is certainly possible. As already mentioned, pathology is accompanied by the onset of certain symptoms even during pregnancy.

As a rule, suspicions of the presence of such a mutation appear during an ultrasound scan. A specialist may note an increase in the volume of amniotic fluid, as well as the presence of abnormalities in the anatomical structure of the skeleton, the absence of hair in the fetus, low fetal body weight, etc.

In the future, genetic studies of the hereditary material are carried out, because, as you know, the karyotype of a patient with Patau syndrome differs from the normal one. The following tests are informative.

Amniocentesis - collection and further analysis of amniotic fluid.
Cordocentesis - the essence of the technique is to obtain samples of umbilical cord blood with its further laboratory examination.
Chorionic villus sampling is a procedure that involves taking the villi using a special probe. This test is prescribed for women with suspicion of Down syndrome, Patau and other chromosomal mutations.

It is worth noting that such studies are associated with risks (for example, there is a possibility of losing a child). After the baby is born, the diagnosis is confirmed after examination by a neonatologist or pediatrician.

Is there an effective treatment?

You already know what Patau syndrome is. The karyotype of a child with this diagnosis is changed, which affects the structure and functioning of the whole organism. Unfortunately, therapy options are very limited. Surgery is sometimes done to correct anatomical abnormalities (such as facial clefts).

The child should be constantly monitored by a pediatric cardiologist, neurologist, ophthalmologist, urologist, ENT, orthopedist, geneticist and other specialists. Your baby needs good care and good nutrition. Symptomatic therapy is performed depending on the presence of certain disorders.

Forecasts for small patients

Today, Patau's syndrome is considered extremely dangerous. it is impossible to change and the forecasts for children are extremely unfavorable. Very often, pregnancy ends in miscarriage.

If the baby is still born, then, according to statistics, rarely live to one year. Only in some developed countries do doctors and parents have the opportunity to extend the life of a child up to 4-5 years. Unfortunately, today medicine cannot offer effective methods of prevention or treatment.

Trisomy is the presence of three homologous chromosomes instead of a normal pair.

The most common in humans is chromosome 16 trisomy (more than one percent of pregnancies). However, the consequence of this trisomy is a spontaneous miscarriage in the first trimester.

Schematic representation of the karyotype of a man with Down syndrome. Non-divergence of G21 chromosomes in one of the gametes led to trisomy on that chromosome.

Among newborns, the most common is trisomy on chromosome 21, or Down's syndrome (2n + 1 = 47). This anomaly, named for the physician who first described it in 1866, is caused by chromosome 21 not separating. Symptoms include mental retardation, reduced disease resistance, congenital heart anomalies, a short, stocky torso and thick neck, and characteristic folds. skin above the inner corners of the eyes, which creates a resemblance to representatives of the Mongoloid race.

Other cases of nondisjunction of autosomes:

Trisomy 18 (Edwards syndrome)
Trisomy 13 (Patau syndrome)
Trisomy 16 miscarriage
Trisomy 9 (the frequency of detection of trisomy 9 among spontaneous abortions is 1: 1000 pregnancies. Almost all conceptions end in intrauterine death of the carrier of the extra chromosome 9. Life expectancy does not exceed three months and two weeks)
Trisomy 8 (Varkani syndrome)

Down syndrome and similar chromosomal abnormalities are more common in children born to older women. The exact reason for this is unknown, but it seems to have something to do with the age of the mother's eggs.

Cases of nondisjunction of sex chromosomes:

XXX (women are outwardly normal, fertile, but mentally retarded)
XXY, Klinefelter Syndrome (men with some secondary female sex characteristics; infertile; poor ovaries, little facial hair, sometimes breasts; usually low mental development)
XYY (tall men with different levels of mental development;)

Tetrasomy and pentasomy

Tetrasomy (4 homologous chromosomes instead of a pair in a diploid set) and pentasomy (5 instead of 2) are extremely rare. Examples of tetrasomy and pentasomy in humans are the karyotypes XXXX, XXYY, XXXY, XYYY, XXXXX, XXXXY, XXXYY, XYYYY, and XXYYY.

Down syndrome causes

Down syndrome is a genetic disorder associated with the abnormal development of 21 chromosome pairs. Down syndrome externally manifests signs in the form of slanted eyes, a flat face, a single transverse fold in the palm of the hand, short stature, a large tongue, etc.

Down syndrome occurs due to the tripling of chromosome 21. The risk of Down syndrome in an unborn child increases when the mother is over 35 years old and the father is over 45 years old.

Down syndrome man

The first description of Down syndrome was given by the English doctor John Langdon Down in 1866. He characterized the disease as a mental retardation in development in conjunction with certain external manifestations. From the point of view of genetics, the characteristic of the disease was determined by Jerome Lejeune in 1959.

In women and men, Down's syndrome manifests itself in equal parts in the same way. In case of Down syndrome, treatment should be directed towards neuropsychiatric rehabilitation, treatment of concomitant diseases, developmental defects, and also include social adaptation of such people.

Why does the disease occur

The cells of a healthy human body have 23 pairs (46) chromosomes. Each of them contains a certain share of genetic information, and each has an impact on the development of a certain characteristic of the organism. Doctors consider it necessary to number pairs of chromosomes from 1 to 23. Down syndrome has the following reasons: when 21 chromosome pairs are tripled, the disease begins to develop. An organism with Down syndrome has not two, but three chromosomes of 21 pairs.

Down syndrome is most often expressed in the form of standard trisomy, when chromosome 21 is completely tripled in all cells of the body. This form of the disease accounts for 94% of all cases. About 4% of cases are occupied by the form of translocation, the displacement of 21 chromosome pairs to the rest of the chromosomes.

The mosaic form of Down syndrome is the most rare form of the disease (about 2% of all cases). With her, tripled chromosome 21 is contained only in some cells of the human body. A sick person, with this form, has a normal appearance, developed intelligence, but children with Down syndrome can be born to him.

Mosaic Down syndrome in newborns will be expressed by a slight developmental delay from peers, and, as a rule, doctors cannot immediately determine the cause of the delay. Adolescents may look similar in appearance to those diagnosed with Down syndrome, but despite this, they can do well in school at the same level as their peers. It is quite difficult to confirm the diagnosis in the mosaic form of Down's syndrome, since only 10% of the cells out of the total number have trisomic form of chromosome 21. A blood test for Down's syndrome involves the donation of blood in large quantities for the karyotype - only in this case, an accurate diagnosis is possible.

Video: Down syndrome

It is very problematic to determine the mosaic Down syndrome during pregnancy, since most of the cells of the fetus will be endowed with the properties of the usual karyotype. Down syndrome in trisomic form makes men infertile, and mosaic form makes possible the function of procreation, but children born in 98% of cases will be endowed with Down syndrome. Unfortunately, with the diagnosis of Down syndrome, in all its forms, it is almost impossible to give birth to healthy offspring.

Most often, Down's syndrome can develop due to:

middle-aged parents, mother over 35 years old, father over 45 years old;

too early, before the age of 18, the age of the mother;

relatives entering into marriage.

With increasing age of parents, there is a high risk of Down syndrome in their future children. Since in the process of aging, the formation of female germ cells is disrupted and, in 25% of cases, male germ cells. Age-related processes affect the division and maturation of germ cells; there is a risk of getting more chromosomes than needed during maturation. And if this "special" cell takes part in fertilization, the resulting embryo will have 23 pairs of chromosomes and +1 more, which will affect its further development and provoke Down syndrome.

Symptoms of the disease

The most common signs of Down syndrome in newborn babies are:

flat face in 90% of cases;

thickened size of the cutaneous cervical fold;

short head shape;

slanting type of eyes;

"Mongolian fold", located in the corner of the eye, capable of covering the lacrimal tubercle.

Upon further examination, children with Down syndrome will have the following signs:

decreased level of muscle tone;
overestimated activity of movable joints;
the hand is short and wide;
flat nape;
arched sky;
deformed shape of the auricles;
large wrinkled nose;
transverse fold in the palm (45% of children);
modified chest (keeled);
located at the edge of the iris of the eye, age spots.

In children with Down syndrome, symptoms from the internal organs may be as follows:

many congenital heart diseases, defects of the interventricular, interatrial septa, anomaly in the development of blood vessels, an unclosed atrioventricular canal;
possible sudden cessation of breathing during sleep, due to the peculiarities of the tongue and pharynx;
defects of the visual system, strabismus, cataract, glaucoma;
abnormalities in the development of the hearing aid;
thyroid disease;
all kinds of pathologies from the gastrointestinal tract;
damage to the musculoskeletal system, dysplasia of the joints, absence of ribs, curved fingers, deformed chest;
insufficient kidney development.

A final diagnosis can be made by performing an analysis for Down's syndrome, while the chromosome set in the baby is examined. Down syndrome in a child leads to a lag in mental and physical development, but despite this, children remain affectionate, attentive, obedient, patient. People with Down syndrome are 20 cm below normal in height, and the degree of their intellectual development depends on the time of the beginning and the volume of rehabilitation procedures.

Diagnosis of the disease

Down syndrome on ultrasound can be diagnosed in the first 12 weeks of pregnancy by detecting specific signs. A Down syndrome test is also performed, in which the thickness of the collar space in the fetus is measured: if it exceeds 2.5 mm, there is a risk of developing the disease. On ultrasound, Down's syndrome can also be determined by the presence or absence of a nasal bone in the fetus.
To diagnose Down syndrome, a biochemical study of the blood of a pregnant woman for up to 13 weeks (hCG) is performed. At 16-18 weeks of pregnancy, a triple test is performed: ACE, hCG, E3.

If the signs of Down syndrome on fetal ultrasound were confirmed, and the biochemical analysis of pregnant women for Down syndrome is positive, you should consult a geneticist for advice. He will prescribe additional examinations: an analysis of the tissues of the membranes of the fetus, amniocentesis. This procedure involves taking amniotic fluid for analysis by piercing the anterior abdominal wall in order to examine the chromosomal set of cells of the unborn baby.

To date, chorionic biopsy and amniocentesis are the most accurate methods for diagnosing possible abnormalities in the development of the fetus. However, this research method is associated with some risk for both the mother and the child. There is a risk of termination of pregnancy, injury to the fetus, development of bleeding, violation of the integrity of the tissues of the internal organs of the pregnant woman.

Treatment and prognosis of the disease

Many are worried about how many people live with Down syndrome. When diagnosed with Down syndrome, life expectancy will not exceed 40-50 years. To date, medical science has not found a way to cure this chromosomal ailment. Although concomitant diseases such as congenital heart disease are successfully overcome, thereby prolonging the life of people with Down syndrome.

A characteristic feature of children with Down syndrome is a delay in the development of the central nervous system. Therefore, in the first trimester of pregnancy, mothers are advised to take folic acid, as it reduces the risk of developing serious pathologies from the nervous system in Down syndrome, and will also make rehabilitation procedures carried out after childbirth more effective.

Video: children with Down syndrome in schools and kindergartens

The treatment process for children should consist of social support and rehabilitation courses. The upbringing and education of children with Down syndrome should reveal the main goal - the ability to adapt in the family and society.

To improve and speed up the process of adaptation of such a child in society, to prepare him for a meeting with the outside world, group lessons will be appropriate. You should not protect the child from being in the children's collective (kindergarten, school), being among peers, a child with Down syndrome quickly gets used to the world around him.

Such "special" children can study in specialized schools, or can attend regular educational institutions - this will only improve the social preparation of the child.

In special rehabilitation centers, psychologists and speech therapists have developed the necessary programs for the development of the personality of the down child. With a properly planned approach and training, sick children will eventually be able to master the same skills and abilities as healthy children.

The effectiveness of rehabilitation procedures can be increased by special medications - nootropics, which stimulate the development of the brain and nervous system. These are aminalon, cerebrolysin + B vitamins.

A properly developed set of rehabilitation measures for children with Down syndrome will allow them to form an adequate personality and lead the whole family a habitual way of life, not to get hung up on the diagnosis of Down syndrome.

Down Syndrome. Karyotype and phenotypic characteristics

Complete trisomy of chromosome 21 is a genetic cause of Down's disease. Cognitive level of newborns with this disease. Hearing, vision, sleep apnea, cardiovascular health. Immunological aspects and dysfunction of the thyroid gland.

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Down syndrome is one of the most common genetic disorders, occurring in about one in 700-1000 newborns. The cause of Down syndrome - the appearance of an extra chromosome of the 21st pair - was identified in 1959, almost 100 years after its first description. As you know, the human chromosome set is a constant species trait and consists of 46 chromosomes or 23 pairs, since all human chromosomes are paired. Sex cells (egg and sperm) contain 23 chromosomes, that is, only one chromosome from each pair. Such cells arise during a special division mechanism - meiosis. During fertilization (the union of the maternal and paternal germ cells), the normal human chromosome set (46 chromosomes) is restored, and an organism develops from the fertilized cell, all of whose cells will have 46 chromosomes. However, sometimes in the process of the formation of the sex cells of a man or woman, a violation of the mechanism of divergence of paired chromosomes occurs, and both copies of one pair fall into the same cell. As a result, the first embryonic cell will contain one more chromosome (47). In Down syndrome, such an "extra" chromosome is the chromosome of the 21st pair, which leads to the so-called regular trisomy-21 (the presence of three chromosomes of the 21st pair).

The vast majority of cases (95%) of Down syndrome have just such a mechanism of occurrence. However, in 3-4% of cases, the extra 21st chromosome, or even only part of it, is attached to another chromosome in the cells of the parents, resulting in a translocation variant of Down's syndrome. This is the only form of the syndrome that can be "inherited" from parents. The fact is that, although in the parent, this rearrangement of chromosomes is balanced (there is no excess or lack of hereditary material) and therefore does not affect his health in any way. When such a cell is connected to a normal cell, a cell with excess chromosomal material appears. In 1-2% of cases, Down syndrome is the result of a violation of cell division after fertilization. Therefore, some of the cells of the fetus have a normal chromosome set, and some have an extra 21st chromosome. This form of Down syndrome is called mosaic. Thus, there are three different variants of Down syndrome. But regardless of the type of chromosomal defect, Down's syndrome manifests itself in a characteristic clinical picture, and its specific form can be determined only with the help of a cytogenetic analysis of the chromosome set.

1. Genetic cause of Down syndrome and its phenotypic features

The genetic cause of Down syndrome was identified by Jerome Lejeune and colleagues, who identified an extra chromosome 21 in nine children with Down syndrome. More often this is the result of complete trisomy of the 21st chromosome, which arose when chromosomes did not diverge in gametogenesis. Translocation forms are much less common (in such cases, a chromosomal study of parents is necessary when planning a subsequent pregnancy), as well as mosaic.

Down syndrome is usually suspected in a baby at birth or during the neonatal period. In deeply premature infants, the diagnosis of the syndrome may be late. If the syndrome is detected antenatally, the decision to prolong the pregnancy is made by the family.

The known phenotypic features of Down syndrome are diverse. John Langdon Down described this syndrome as mental retardation in patients with high susceptibility to infections and low life expectancy. The two persistent signs of Down syndrome - mental retardation and neonatal hypotension - can be associated with a wide range of other abnormalities, such as congenital heart disease, gastrointestinal malformations, endocrine and hematologic dysfunctions, growth retardation with craniofacial abnormalities, microcephaly, and psychiatric symptoms. At the same time, the presence of all the described anomalies in each particular child is not at all necessary.

Patients with Down syndrome are characterized by the preservation of physical features characteristic of the early stage of fetal development, including narrow slanting eyes, which give patients an external resemblance to people of the Mongoloid race, which gave L. Down the reason to call this disease "Mongolism" in 1866 and suggest an erroneous the theory of racial regression, or evolutionary rollback. Down syndrome is actually not racial and occurs in all races.

The cognitive level of newborns with Down syndrome may be relatively high (IQ 70 to standard newborn IQ 80); there is a low rate of development, and not a loss of already acquired skills. The delay in psychomotor development usually increases by half a month with each month of chronological age. Defects in expressive speech and decreased intellectual development are predominant in early and middle preschool age, given that non-verbal, social and play acquired skills remain relatively constant. In addition, with the improvement of medical care, the average life expectancy of people with Down syndrome increases, from 25 years from 1983 to 49 years in 1997, and on average increases annually by 1.7 years.

2. Growth and development of children with Down syndrome

Children with Down syndrome have slow growth rates from birth to the end of the growth period, with the lowest rates in infancy and adolescence. The reason for the stunting is not clear. On average, the height of women is 145 cm, and of men - 157 cm. It is noted that children with Down syndrome who are brought up in families are higher than their peers in specialized institutions. By the age of one year, these children show an increase in average weight in relation to height, and excessive weight is a significant problem in adults with Down syndrome.

One of the main causes of early mortality in children with Down syndrome is congenital heart defects, the frequency of which, according to the literature, reaches 50%.

Among heart defects, the most common are perimembranous septal defect, persistent ductus arteriosus, atrial septal defect, common open atrioventricular canal (AVK), tetralogy of Fallot and other defects, accounting for less than 1%.

A special role is played by early diagnosis of congenital heart defects, while it is mandatory to conduct an ultrasonographic examination and timely (before the development of severe circulatory failure) the appointment of conservative treatment or surgical correction.

In adults with Down syndrome, in the absence of a history of heart disease, acquired diseases, including mitral valve prolapse with increasing mitral valve insufficiency, may occur. It is also necessary to prevent bacterial endocarditis in patients with mitral regurgitation and especially those who have undergone surgery.

Hearing, vision, sleep apnea.

More than half of adults with Down syndrome have conductive or sensorineural hearing loss. People with undiagnosed hearing loss experience increased learning and communication difficulties. For the timely detection of hearing problems, an audiometric study should be carried out at least once every two years.

Sleep apnea (obstructive) occurs in almost half of people with Down syndrome and is not always diagnosed by doctors. Snoring during sleep, drowsiness, sleeping in unusual positions (on the stomach with bent knees) can be signs of apnea. In this case, one cannot do without an otolaryngological examination and sleep studies to prevent complications such as pulmonary hypertension and cor pulmonale.

Ophthalmologic examination is indicated for all children annually, and for adults with Down's syndrome - once every two years.

People with Down syndrome often have deficiencies in both cellular and humoral immunity. Patients with frequent intercurrent illness should be consulted by an immunologist. Deficiency of cellular immunity plays an important role in the development of gingivitis, periodontitis with loss of teeth.

Thyroid dysfunction.

Hypothyroidism, including congenital hypothyroidism, occurs in about 10-40% of people with Down syndrome. Neonatal screening is very important given the fact that clinical examination may not be sufficient given the difficulty of diagnosing hypothyroidism in children with Down syndrome, in part due to overlapping features. In adults with Down syndrome, hypothyroidism can be disguised as other diseases, so annual monitoring of thyroid hormone levels is warranted. Treatment of subclinical hypothyroidism (increased thyroid-stimulating hormone (TSH) levels with normal T4 values) is controversial. The interrelation of subclinical hypothyroidism with hypozinkaemia and the normalization of TSH parameters during the replacement of zinc deficiency are described. The increased frequency of acquired diseases of the thyroid gland occurs at the age of 30-50 years.

Weakness of the ligamentous apparatus.

It is known that people with Down syndrome have a weak ligamentous apparatus, which can lead to disorders such as flat feet, scoliosis, and knee instability. Signs of atlantoaxial instability occur in about 13% of adults with Down syndrome, with fewer than 1.5% having clinical symptoms (in these cases, surgery is required). Although the follow-up of patients with asymptomatic atlantoaxial instability is controversial, caution and possibly withdrawal from neck-flexing sports (eg, diving) are generally recommended. X-ray screening for atlantoaxial instability is indicated for anyone wishing to participate in the Special Olympics.

Women with Down syndrome can have children. The risk of having a child with Down syndrome is 50%, but the risk of developing other congenital anomalies in children from women with Down syndrome is significantly higher.

Men with Down syndrome are infertile. Almost half of them have hypogonadism and cryptorchidism, while it is known about an increased risk of developing testicular germinal tumors.

The combination of Down syndrome and Alzheimer's disease is a difficult diagnostic and therapeutic task for the doctor. The clinical picture of Alzheimer's disease in people with Down syndrome is rather complex, given the premorbid decline in cognitive functions and atypical symptoms.

According to studies, the average age at onset of Alzheimer's disease in adults with Down syndrome is 54.2 ± 6.1 years. On the prevalence of Alzheimer's disease among people with Down syndrome, various data are given in the literature - from 6 to 75%.

Much research is needed to investigate this problem, especially on the treatment of Alzheimer's disease in individuals with Down syndrome.

Currently, the feasibility of anti-inflammatory therapy, the use of estrogens and secretase inhibitors (which can prevent the deposition of β-amyloid and thus stop the development of Alzheimer's disease) is being studied. The possibilities of using vitamins C and E are being studied.

Research is already underway on the prophylactic use of acetylcholinesterase inhibitors in Down syndrome and Alzheimer's disease, but this method requires more in-depth evaluation.

trisomy down genetic cognitive

As foreign experience shows, the improvement of medical care for children and adults with Down syndrome has significantly improved the quality and duration of their life. An attentive approach, timely assistance, and most importantly, the prevention of concomitant diseases will allow children and adults with this syndrome to maximize their potential.

Bibliography

1. Journal “Down Syndrome. XXI century "edited by N.А. Uryadnitskaya, edition No. 1, 2008.

2. “Changes and continuity in the social competence of children with autism, Down syndrome, and developmental delays. Monograph of the Society for Research in Child Development ”, authors: M. Sigman and E. Raskin, 1999.

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Down Syndrome

Down syndrome is a genetic abnormality in which a person has 47 chromosomes instead of 46 due to the fact that one extra chromosome appears in their 21-pair.

Down syndrome has been known to mankind for a long time, back in the 19th century, doctors observed children with a set of characteristic features of their appearance, trying to understand what unites them and why such children are born. And in 1862, the English scientist John Langton Down first described the syndrome, but due to the level of development of medicine at that time, he attributed it to mental disorders, because electron microscopes were not available to him to find the real cause of the anomaly.

Most children with this syndrome died before reaching adulthood. With the development of civilization and science, when doctors learned to stop at least a number of symptoms, their lifespan increased, and the number of adults suffering from Down syndrome increased. But society was in no hurry to accept them - at the beginning of the twentieth century in some countries adults with this diagnosis were subjected to forced sterilization, and in Nazi Germany and its occupied territories it was ordered to cleanse the population of such patients. And only from the second half of the twentieth century, mankind, finally, came to grips with this problem.

It was very important to find the cause of the syndrome. Despite the fact that the connection between the age of the parents and the possibility of giving birth to a Down-child has long been noticed, the causes of the disease were sought either in the psyche, then in heredity, or in difficult childbirth. Finally, in 1959, the French scientist Jerome Lejeune suggested that the source of the disease lies somewhere in the chromosomes. Having studied the karyotype of patients, he established a connection between the available third chromosome in the 21st pair and the presence of the disease. It was also confirmed that the possibility of having such a child is influenced by the age of the parents, and the mother to a greater extent than the father. If the mother is between 20 and 24 years old, the probability of this is 1 in 1562, before 30 years old - 1 in 1000, from 35 to 39 years old - 1 in 214, and over the age of 45, the probability is 1 in 19. Although the probability increases with the mother's age , 80% of children with this syndrome are born to women under the age of 35. This is due to the higher birth rate in this age group. According to the latest data, paternal age, especially if over 42 years old, also increases the risk of the syndrome. At the same time, the behavior of the parents, their lifestyle and nationality do not affect this possibility in any way: Down children are born with the same frequency, regardless of nationality, place of residence and other factors.
Down syndrome is not a rare condition. According to statistics, one in 700 children conceived is a carrier, but among children born, the number of carriers decreases to one in 1100 children. This discrepancy is explained by the fact that some pregnancies are terminated naturally, a miscarriage occurs, and, which is very painful to talk about, very often women, having learned that they will have a child with this syndrome, have an abortion. Over the past decade, religious and public organizations around the world, including the Russian Orthodox Church in Russia, have been drawing public attention to this problem, to the ethical side, explaining that Down syndrome is not as terrible as it might seem, therefore, it is gradually possible to reduce the number of abortions. in this connection, the number of registered cases of births of children with Down syndrome is increasing every year.

In humans, Down's syndrome is usually associated only with mental retardation. However, polysomy on the 21st pair of chromosomes causes many more complications in the human body than it might seem at first glance. People with Down syndrome are most often diagnosed with:

"Flat face" - 90%
brachycephaly (abnormal shortening of the skull) - 81%
skin fold on the neck in newborns - 81%
epicanthus (vertical skin fold covering the medial angle of the palpebral fissure) - 80%
joint hypermobility - 80%
muscle hypotension - 80%
flat nape - 78%
short limbs - 70%
brachymesophalangia (shortening of all fingers due to underdevelopment of the middle phalanges) - 70%
cataracts over the age of 8 years - 66%
open mouth (due to low muscle tone and special structure of the palate) - 65%
dental abnormalities - 65%
clinodactyly of the 5th toe (twisted little finger) - 60%
arcuate palate - 58%
flat bridge of the nose - 52%
grooved tongue - 50%
transverse palmar fold (also called "monkey") - 45%
short wide neck - 45%
CHD (congenital heart disease) - 40%
short nose - 40%
strabismus (squint) - 29%
deformity of the chest, keeled or funnel-shaped - 27%
age spots along the edge of the iris = Brushfield spots - 19%
episyndrome - 8%
stenosis or atresia of the duodenum - 8%
congenital leukemia - 8%

However, at the same time, it is necessary to know that the diagnosis is made solely by the results of a blood test for the karyotype. It is impossible to diagnose Down syndrome based only on external signs.

How does the life of a person with such a diagnosis develop?

Despite the fact that most people with Down syndrome suffer from mental retardation and delayed psycho-speech development, this condition is successfully corrected by rehabilitation measures carried out in childhood. Experience shows that with the correct attitude to the child on the part of the parents, he is not much different from ordinary children. Down children are trainable, they relatively easily master the usual everyday life skills. Moreover, people with Down syndrome are able to achieve good success in the profession: they can work as waiters, administrators, salespeople, receptionists, storekeepers. An actor Chris Burke, known to the Russian audience for the films "Ambulance" and "The Smile of Mona Lisa", who has Down syndrome, lives in the United States. Portuguese Pablo Pineda became the first person in Europe with Down syndrome to receive a university education and choose the profession of a teacher. A society inspired by the examples of these people must stop shying away from those who live with Down syndrome. This is not the most serious illness that exists, although, of course, raising and adapting a child with this syndrome requires a lot of physical and emotional commitment from the parents.

People with Down syndrome marry successfully, with most men sterile, and 50% of women are capable of conceiving and having children. In a pair of a healthy man + a Down woman, the probability of having a child with Down syndrome reaches 50%, the other 50% of children are born healthy.

The average life expectancy of persons with Down syndrome in modern conditions is more than 50 years. However, due to the existing congenital diseases, they develop Alzheimer's disease (senile dementia) much earlier than healthy people, in addition, with age, the state of health is complicated by the development of cardiac diseases and leukemia. In addition, such people have weakened immunity, and they, in principle, get sick more often, more severely and for longer than ordinary people.

The main problem of people with Down syndrome at this stage is the reaction of society to them. Unfortunately, many people in Russia have not learned to perceive them as full-fledged members of society, the Down people cause fear and rejection, they are extremely reluctant to be hired for fear that they will not cope with their duties, and because of their "unrespectable" appearance ... Another important problem is the high number of abortions performed by women whose fetus has been diagnosed with the syndrome. According to statistics, even in prosperous economically developed countries, in 90% of cases, women decide to terminate a pregnancy. Church communities should intensify their efforts to explain that it is quite possible to live with Down syndrome, it is necessary to convince mothers that abortion is a mistake in such a diagnosis.

Karyotype analysis question: disease or down syndrome?

ulya2: The question of the karyotype and types of Down syndrome is discussed and discussed in detail here: http://downsyndrome.borda.ru/?1-1-40-00000031-000-0-0-1230646216 Moderator I do not know where to ask this question I decided here , is it possible to determine the disease or down syndrome by the analysis for the karyotype? Our cardiologist proposed to formalize disability due to a large heart defect, adding at the same time "all the more you have down syndrome" when I said that with the syndrome, disability is not given, you answered, do the analysis, you will find out you have a disease or syndrome. With the analysis for the karyotype, we got a problem, did 35 days, explained that at first there was no growth, and then it grew.I don't know how in genetics, but in my opinion, if something should grow, then immediately, especially from the forum I learned that the analysis it takes from 4 days to two weeks, maybe I'm wrong?

Meri: The word "syndrome" refers to a collection of traits or characteristics. Down syndrome, as the French scientist Lejeune showed in 1959, is a genetic condition that exists from the moment of conception and is determined by the presence of an extra chromosome in human cells. This condition was named after the English physician John Langdon Down, who first described its symptoms in 1866. The human body is made up of millions of cells, each of which usually contains 46 chromosomes. Chromosomes are located in pairs - half from the mother, half from the father. In people with Down syndrome, the 21st pair has an extra chromosome, as a result of which 47 chromosomes appear in the cells. Moreover, the parents, as a rule, have a normal genotype. click here Down's disease is only in the minds of incompetent doctors. click here Read here, a similar topic has been discussed elsewhere, but it's not easy to find.

ulya2: Meri writes: Down's disease is only in the minds of incompetent doctors. I thought so too, but after talking with the doctor I began to doubt, especially after her words "I'm a doctor, I know better" and now I don't know if we should retake the analysis to find out for sure whether we have a syndrome or an illness.

Hope: As the geneticists told me, before the general check of karyotypes, the syndrome was written in the presence of simply similar features (externally, physiological, suitable for the syndrome), and if it was confirmed by the analysis of the karyotype, they set the disease. The gradation exists only in forms - complete trisomic, transgenic and mosaic. Although our miracle doctors, in addition to the syndrome and the disease, can also single out “Downism”. Girls on the forum wrote that even neurologists are guilty of this. So any of the mothers who have encountered this problem, I'm afraid, knows a lot more than any doctor.

G-NA85: Nadezhda writes: Although our miracle doctors, in addition to the syndrome and the disease, can also single out "downism" Yes, the neuropsychologist wrote Apollinaria on the card. I made him redo on Down Syndrome. It sounds prettier that way. Down's disease is not. There is Down's Syndrome - trisomy or just outward signs of diabetes - without trisomy, but an experienced doctor writes Down Syndrome. The external signs are not taken into account at all - if they are not backed up by three chromosomes. ulya2 writes: Answer you will make an analysis, you will find out whether you have a disease or a syndrome. What STUPID vrchi there are, just oaks, well, take you, aunt-doctor, read the book before littering the airwaves with nonsense, there is no sculpting nonsense, only poor mothers are forced to spend money on tests in vain and stab the child in vain.

Hope: G-NA85 writes: Down's disease is not. There is Down's Syndrome - trisomy or just outward signs of diabetes - without trisomy, but an experienced doctor writes Down Syndrome. The external signs are not taken into account at all - if they are not backed up by three chromosomes. Tanya, well, you and I (and other mothers of our children) know this, but many doctors, as my mother-in-law put it, when I asked what methods there are for teaching (she is a teacher): “I have nothing to study this problem for, and once "So really, OAK

OlgaLD: ulya2 Terminology questions, don't worry. Good luck!

klimenko: Recently, I passed a commission with Marusya and the pediatrician asked me if the child has Down syndrome or disease? and it is useless to deal with them?

OKS: Girls! And our diagnosis is simply "trisomy on chromosome 21". Agree, it sounds neat.

lusya: Girls now, after all, diagnoses are written under the numbers. Down syndrome encrypted looks like this - Q 90. How beautiful it sounds, right?

Mariyka: And our doctors are at a loss to guess whether to write a syndrome or a disease. Who wants to seem smart in this matter writes "disease", and those who already know - "syndrome". Who is in that much. They have to come to an agreement with each other. Sometimes you just want to hold LIKBEZ specially for them.

Laura: I would like to remember where I read. but the bottom line is that if it's just a chromosome set and external signs, then this is a syndrome. And if there are also developmental defects, mental retardation, then already a disease. We, too, are often asked by doctors: what do you have, a syndrome or a disease. And they write everywhere: illness. Even in the conclusion of geneticists it is written: the diagnosis of Down's disease (translocation variant). I quote verbatim.

Laura: I also found it. Textbook for medical schools, author Bisyarina V.P., year of publication 1981 "Children's diseases and childcare." Here they write about Down's disease. Maybe that's why all doctors say so? They studied according to this textbook (or according to the same, published by the publishing house "Medicine").

G-NA85: Laura writes: ... And if there are also developmental defects, mental retardation, then already a disease. And in my opinion, all of our children have some developmental defects and SD, mostly in a mild form. Vices are also different for everyone, but some small things will be scraped off each. Therefore, it is still correct - DOWN'S SYNDROME, not a disease. Disease is the old-fashioned way and only on the territory of the former Soviet Union, where a doctor is too lazy to take a book in his hands. And the truth is what to learn? There is a diploma, a white dressing gown was given.

Meri: Syndrome - definitions on the Internet: Syndrome (σύνδρομον, σύνδρομο, "equal, in agreement") - a combination of symptoms. ru.wikipedia.org/wiki/Syndrome is a natural combination of symptoms due to a single pathogenesis; considered as an independent disease (for example, Meniere's syndrome) or as a stage. www.medotvet.ru/dict/zabol/glossary/homemed_glossary_s.php is a natural combination of signs (symptoms) that have a common mechanism of occurrence. dic.paludarium.ru/017.htm (Greek syndrome - concatenation of disease symptoms; synonym symptom complex) - a set of symptoms united by a single disease mechanism; sometimes this term denotes. www.magalif.ru/index.php complex of symptoms. www.infospid.ru/index.php a condition that develops as a consequence of the disease and is determined by a combination of clinical, laboratory, instrumental diagnostic signs. www.ssmu.ru/ofice/sibcem/glossary/protocols.shtml a set of symptoms typical for this disease. zoolife.com.ua/pageid1006.html That is, the symptom and the disease are in one bundle. The time comes and all the same it becomes, as they call it, a syndrome, a disease - trisomy21 more precisely.

Laura: OKS, about translocation is very well written in some topic by Tatiana Spomer. Even a photo of chromosomes. In short, this is when not 3 21 chromosomes, but 2, but one of them has attached itself to some other pair. Or they have grown together, forming one abnormal. So our Arseny, the total number of chromosomes is 46. And how is it written in your analysis? Or didn't you?

OKS: Laura We did. Unfortunately, we have 47. I just got curious about the translocation. And it is written like this: karyotype: 47, XX, + 21.21ps +. Here. Conclusion: trisomy on chromosome 21.

Laura: OKS why “unfortunately”? We also have a syndrome, despite 46 chromosomes. Typical appearance, heart disease, developmental delay. And if, with your diagnosis, it is more or less clear that the chromosomes have not unfolded, then we do not understand how one got into the other pair. Looked at the seagulls and stayed? How is it that the chromosomes "run away", I wonder if the specialists have an answer?

lilka: Yesterday they called a doctor to the house, an old Russian woman came. We immediately told her that the child had Down syndrome. She agreed, said: “Yes, you have the syndrome, not Down himself. Down is much harder. " We had some fun.

Irene: They told us at the Pediatric Institute: “Down disease is when almost all organs are affected, down syndrome is a small part.” When we came, they immediately asked, “Do you have a disease or a syndrome?”

Irene: OKS They meant the accompanying "sores".

ulya2: no where can I find what 13 means in our analysis result Karyotype: 47, XX, + 21 maybe who knows here?

G-NA85: Maybe shoulder 13 of chromosome fell on shoulder 21 and they did not split (this is a primitive explanation). I once asked a geneticist about these shoulders, although Apollinaria has a different analysis. It looks like a translocation. You need to consult.

ulya2: I was told that it looks like a tralocation, but the conclusions say one thing: The karyotype is abnormal, unbalanced. Trisomy on chromosome 21. Down's syndrome. in another: Trisomy on chromosome 21. I already regret that I passed the analysis for the second time, I found myself an extra headache. The first time we rented in our city, because. the genetic center appeared recently, there was a hope that they were mistaken, and the geneticist was not very smart, he offered to abandon his daughter. So we decided to take it again in Novosibirsk, when we went to the operation, this figure appeared there 13

Assol: Ulya, we had numbers in square brackets in our karyotype, but we have a mosaic, and it was like 46ХУ (15), 47ХУ (20). As far as I understood, the number in brackets meant how many cells with such a set were found, since the geneticist said we have about 50/50. Maybe you have something similar too?

ulya2: So we can have a mosaic? Probably you need to call the Novosibirsk laboratory, they did not answer the email, but I don’t want to meet with our geneticist

Svetlana: ulya2 writes: Probably need to call the Novosibirsk laboratory, the email was not answered I think they won't answer the phone either. This is strictly prohibited - medical secret is not an abstract concept at all. They have the right to provide such information only in person. At one time, we were only told by phone that the analysis was already ready and that we could come to pick up.

Assol: ulya2 writes: So we might have a mosaic? As far as I understand, your karyotype only says about 47 chromosomes, and about 46 - nothing. Then it is hardly a mosaic, with a mosaic and 46 chromosomes there are, and 47. Maybe 13 in your case - that 13 cells have been checked. Or maybe it still means something

G-NA85: It doesn't look like a mosaic, there really should be 46 chromosomes written. Check with any geneticist other than yours. We were told that this is a translational form when describing the possible options. Although Apollinaria has a simple trisomy, but according to our (parental) analyzes, there should be a translocation. In fact, it makes no difference. I was only interested in this for the first two months, and then I scored on these chromosomes, well, them. You can't see them anyway.

Alexa and Lyosha: G-NA85 Did you have any tests before or after Apollinaria's birth? We are thinking about the next child and do not know what to do. Although after everything that happened to us (we observed the entire pregnancy in geneticists: triple test, amniocynthesis, ultrasound - everything is fine) it is hard to believe that they will help us in any way.

Lena S.: Alexa and Lesha writes: Although after everything that happened to us (we observed the entire pregnancy in geneticists: triple test, amniocynthesis, ultrasound - everything is fine) it is hard to believe that they will help us in any way. Sorry, but what, the amnio did not show the presence of an extra chromosome? Or did the cells not hit? Indeed, who can then guarantee something.

Alexa and Lyosha: Lena S. It was only after Lesha's birth that they told me that the reliability of the analysis for amniocynthesis is about 75% (part of the amniotic fluid may not contain fetal cells), and that the study at the 10th week of pregnancy is more reliable - a chorionic biopsy, but there is also reliability 98%. And where is the guarantee that you will not get into 2% ?! Moreover, we did the amniocynthesis on our own initiative, just because I was 35 years old, the doctors were a little perplexed, the triple test is good, Voevodin himself did not find any pathologies on the ultrasound. And now I think, what was it - a premonition? No, I just wanted to do everything right, as it is written in the books. But now I know that I did everything possible to prevent this situation. Child of God, that's the whole explanation!

Assol: Alexa and Lyosha It turns out that the amnio predicted the birth of a girl? After all, if it was not the baby's cells that came from the amniotic fluid for analysis, then it was your cells, there should have been a set of XX. And have you seen the boy by ultrasound?

Alexa and Lyosha: РђСЃСЃРѕР »СЊ We passed amniocynthesis in order to identify genetic pathologies, and not to find out the sex of the child. The topic of the gender of the child was not discussed with the geneticist at all. We found out that we will have a boy at 24 weeks of pregnancy, 4 weeks after the amnio.

Assol: Alexa and Lesha writes: We passed amniocynthesis in order to identify genetic pathologies, and not to find out the sex of the child. This is understandable, just the sex of the child in this analysis is determined automatically when the chromosomes are examined. But you, apparently, were not told, and you did not ask.

anonymous: Hello! Tell me please. we did an analysis for the karyotype and the result is as follows: 47, Xy, + 21 and additionally: Q90.0 Trisomy 21, Meiotic nondisjunction

OlgaLD: anonymous Hello, welcome to the forum! This means that your child has Down syndrome, the most common form is chromosome 21 trisomy. This is indicated by the code Q90.0. Meiotic nondisjunction corresponds to normal trisomy. turist writes: Karyotype 47, xx; +21, that is, an additional 21 chromosome was found in all examined cells. And the diagnosis is Q 90.0 (otherwise they say trisomy 21 - meiotic nondisjunction), if Q 90.1 is written, then Trisomy 21, mosaicism (mitotic nondisjunction) Q 90.2 Trisomy 21, translocation http://www.downsyndrome.borda.ru/?1-9-0-00000099-000-120-0 Translocation and mosaicism occur each in 4-5% of cases, the remaining 90% + are ordinary trisomies. The karyotype is represented by 47 chromosomes instead of the normal 46, since the chromosomes of the 21st pair, instead of the normal two, are represented by three copies (trisomy). Hence the number 47 in your analysis and the addition of "+21". In other words, "trisomy 21". Meiotic means what happened during meiosis, meiosis means cell division. In other words, Down syndrome occurs when chromosomes do not diverge during meiosis, cell division, i.e. present at conception. She seems to have explained everything. Welcome to the forum! Read these pages: http://sunchildren.narod.ru/whatis.html http://sunchildren.narod.ru/whatdo.html http://sunchildren.narod.ru/startwith.html Write where you can find compatriots who will help you get comfortable with the diagnosis and find answers to your questions.

KaRinaSH: People, they read me a lecture today at the RC that type D disease and diabetes mellitus are two different things, but if there is no heart defect, then it’s diabetes, but I read it here.

OlgaLD: KaRinaSH You are not the first, you are not the last, you can read this topic, but in general, this infa from "specialists" often pops up on our forum

Tatiana A: And we have written on a piece of paper with the analysis 46, xx, der (14:21) (g10: 10) +21 translocation

OlgaLD: Tatyana Well, you have a translocation form, more rare

wap.downsyndrome.borda.ru

Down syndrome karyotype

Clinical diagnosis of Down syndrome usually does not present any difficulties. However, karyotyping is necessary to confirm the diagnosis and provide a basis for genetic counseling. Although differences in the specific karyotype variants responsible for Down syndrome usually have little effect on the patient's phenotype, they are significant in determining the risk of recurrence.

Trisomy 21 with Down syndrome... About 95% of all patients with Down syndrome have chromosome 21 trisomy caused by meiotic nondisjunction of 21 pairs of chromosomes, as discussed in the previous chapter. It has already been noted that the risk of having a child with trisomy 21 increases with the age of the mother, especially after 30 years. The meiotic error responsible for trisomy usually occurs during maternal meiosis (about 90% of cases), predominantly in the first division, but about 10% of cases occur in paternal meiosis, usually in the second division.

Robertsonian translocation in Down syndrome... About 4% of patients with Down syndrome have 46 chromosomes, one of which is a Robertsonian translocation between chromosome 21q and the long arm of one of the other acrocentric chromosomes (usually chromosomes 14 or 22). The translocated chromosome replaces one of the normal acrocentric chromosomes, and the karyotype of a patient with a Robertsonian translocation between chromosomes 14 and 21 is 46, XX / XY, rob (14; 21) (ql0; ql0), + 21.

Such chromosome can also be defined as der (14; 21), in practice both nomenclatures are used. In fact, patients with a Robertsonian translocation involving chromosome 21 are trisomal for genes located in the long arm 21q.

Unlike standard trisomy 21, translocation Down syndrome does not show any connection with the age of the mother, but has a relatively high risk of recurrence in families if one of the parents, especially the mother, is a carrier of the translocation. For this reason, karyotyping of the parents and possibly other relatives is important for accurate genetic counseling.

Carriers Robertsonian translocation, including chromosomes 14 and 21, have only 45 chromosomes; one 14 and one 21 are missing and replaced by a translocated chromosome. Six types of gametes are theoretically possible, but three of them cannot lead to viable offspring. The three types of gametes are viable, normal, balanced and unbalanced, with both translocated and normal chromosome 21. Combined with a normal gamete, this can lead to the conception of a child with translocation Down syndrome.

In theory, these three types gametes are produced in equal quantities, so the theoretical risk of a child with Down syndrome should be 1 in 3. However, expanded population studies have shown that imbalanced chromosome sets appear in only 10-15% of the offspring of mothers and only a few percent of offspring of fathers carrying translocations involving chromosome 21.

21q21q translocation in Down syndrome... Chromosomal translocation 21q21q - chromosome formed from two long arms of chromosome 21; occurs in several percent of patients with Down syndrome. They are thought to appear as isochromosomes rather than Robertsonian translocations. Most of these cases occur postzigotically, so the risk of recurrence is low. However, it is especially important to make sure that the parent is not a carrier (possibly mosaic) of this translocation, since all the gametes of the carrier of such a chromosome must also contain the 21q21q chromosome, with a double dose of the genetic material from chromosome 21, or not have chromosome 21 at all.

Potential offspring therefore inevitably has either Down syndrome or nonviable monosomy 21. Mosaic carriers have an increased risk of recurrence, thus prenatal diagnosis is necessary in all subsequent pregnancies.

Mosaic Down Syndrome... About 2% of Down syndrome patients are mosaic, usually with populations of normal cells and with trisomy 21. The phenotype may be milder than typical trisomy 21. In general, there is wide variation in the phenotypes of mosaic patients, probably reflecting the different proportions of trisomal cells in the embryo on early stages of development. It is possible that patients with established mosaic Down syndrome only reflect clinically more severe cases, since mild cases are less likely to be karyotyped.

Partial trisomy 21 in Down syndrome... Very rarely, Down syndrome is diagnosed in patients with trisomy only on a part of the long arm of chromosome 21, and even less often in patients with Down syndrome without a cytogenetically visible chromosomal abnormality. Such cases are of some interest, since they can indicate which region of chromosome 21 is probably responsible for specific components of the phenotype of Down syndrome and which regions can triple without causing phenotypic manifestations.

Though chromosome 21 contains only a few hundred genes, attempts to match a triple dose of specific genes with specific aspects of the Down syndrome phenotype have so far met with limited success. Most notable was the identification of an area critical for heart defects seen in about 40% of Down syndrome patients. The search for specific genes essential for the manifestation of the phenotype of Down syndrome, among those randomly adjacent to them on chromosome 21, is the main task of modern research, especially in mice as a model.

Potentially promising direction- study of genetically engineered mice with an additional dose of genes from human chromosome 21 (or even with a full copy of chromosome 21). Such mice can exhibit phenotypic abnormalities in behavior, brain function, and heart formation.

A karyotype is a set of characteristics of a chromosome set (number, size, shape of chromosomes) characteristic of a particular species.

The study of all elements of the human karyotype is carried out using a special staining method and subsequent study of chromosomes in a light microscope. This method helps to see the size and shape of chromosomes,
their structure. Diseases accompanied by pathological changes in the karyotype are called chromosomal. Example
chromosomal disease - Down syndrome. The causes of Down syndrome lie in the intrauterine formation of the chromosomal pathology of the fetus. So, if the normal karyotype of a healthy person consists of 46 chromosomes, then in Down's syndrome it is formed by 47 chromosomes, in 21 pairs an additional chromosome is found that is responsible for the disease.

An abnormal karyotype is found in about 1% of all newborns. The consequences of such abnormalities can range from death to mental retardation and mild anomalies. Cases of abnormal chromosome numbers increase with the age of the mother. The age of the mother-to-be also affects the risk of a child developing Down syndrome: if before the age of 35, this risk is 1 in 1000; then before the age of 40, the risk increases to 1 in 214; over the age of 45, the risk increases to 1 in 19.

There are many options for deviations from the norm. To date, the following anomalies have been identified:

Down Syndrome

Cat Scream Syndrome

Patau syndrome

Klinefelter's syndrome

Shereshevsky-Turner syndrome

Prader-Willi syndrome

Polysomies on the X chromosome

This happens already at an early stage of embryonic development. One of the reasons for the deviations is the violation of spermatogenesis, some of the disturbed spermatozoa are still involved in the fertilization of the egg and, therefore, can cause the formation of an embryo with a disturbed karyotype.

The main unfavorable factor in the appearance of deviations is poor ecology, which provokes chromosomal mutations. All these anomalies are inherited.

There is currently no content classified by this term.

Down syndrome mosaic form: how to determine

The genetic pathology caused by changes in chromosome 21 is mosaic Down syndrome. Let's consider its features, methods of diagnosis, treatment and prevention.

Down's disease is one of the most common congenital genetic disorders. It is characterized by a pronounced mental retardation and a number of intrauterine abnormalities. Due to the high fertility of children with trisomy, a lot of research has been done. Pathology is found in representatives of all peoples of the world, therefore, geographical or racial dependence has not been established.

ICD-10 code

Epidemiology

According to medical statistics, Down syndrome occurs in 1 child in every 700-1000 births. The epidemiology of the disorder is associated with certain factors: hereditary predisposition, bad habits of the parents and their age.

The regularity of the spread of the disease is not related to the geographical, gender, nationality or economic status of the family. Trisomy is caused by disorders in the development of the child.

Causes of mosaic Down syndrome

The main causes of mosaic Down syndrome are associated with genetic disorders. A healthy person contains 23 pairs of chromosomes: female karyotype 46, XX, male 46, XY. One of the chromosomes of each pair is passed on from the mother, and the other from the father. The disease develops as a result of a quantitative violation of autosomes, that is, extra genetic material is added to the 21st pair. Trisomy on chromosome 21 is responsible for the symptoms of the defect.

Mosaic syndrome can occur for the following reasons:

Somatic mutations in the zygote or in the early stages of cleavage.

Redistribution in somatic cells.

Segregation of chromosomes during mitosis.

Inheritance of a genetic mutation from a mother or father.

The formation of abnormal gametes can be associated with some diseases of the genital area of the parents, radiation, smoking and alcoholism, taking medications or drugs, as well as with the ecological situation of the place of residence.

About 94% of the syndrome is associated with simple trisomy, that is: karyotype 47, XX, 21+ or 47, XY, 21+. Copies of chromosome 21 are present in all cells, since during meiosis, the division of paired chromosomes is disrupted in parental cells. About 1-2% of cases are caused by impaired mitosis of embryonic cells at the stage of gastrula or blastula. Mosaicism is characterized by trisomy in the derivatives of the affected cell, while the rest have a normal chromosome set.

In the translocation form, which occurs in 4-5% of patients, the 21st chromosome or its fragment is translocated to the autosome during meiosis, penetrating with it into the newly formed cell. The main objects of translocation are 14, 15, less often 4, 5, 13 or 22 chromosomes. Such changes can be accidental or inherited from the parent, who is the carrier of the translocation and normal phenotype. If the father has such disorders, then the risk of having a sick child is 3%. When carriage by the mother - 10-15%.

Risk factors

Trisomy is a genetic disorder that cannot be acquired in a lifetime. The risk factors for its development are not related to lifestyle or ethnicity. But the chances of having a sick child increase under the following circumstances:

Late childbirth - women in childbirth 20-25 years old have minimal chances of giving birth to a baby with the disease, but after 35 years, the risk increases significantly.

Father's age - many scientists argue that genetic disease does not depend so much on the age of the mother as on how old the father is. That is, the older the man, the higher the chances of pathology.

Heredity - medicine knows a case when a defect was inherited from close relatives, taking into account the fact that both parents are absolutely healthy. At the same time, there is a predisposition only to some types of the syndrome.

Incest - marriages between blood relatives entail genetic mutations of varying severity, including trisomy.

Bad habits - negatively affect the health of the unborn baby, so tobacco abuse during gestation can lead to a genomic anomaly. The same is observed with alcoholism.

There are suggestions that the development of the malaise may be associated with the age at which the grandmother gave birth to the mother and other factors. Thanks to preimplantation diagnostics and other research methods, the risk of having Down's baby is significantly reduced.

The development of a genetic disease is associated with a chromosomal abnormality, in which the patient has 47 chromosomes instead of 46. The pathogenesis of mosaic syndrome has a different development mechanism. The sex gamete cells of the parents have a normal number of chromosomes. Their fusion led to the formation of a zygote with a karyotype 46, XX or 46, XY. During the division of the original cell, the DNA malfunctioned and the distribution was incorrect. That is, some of the cells received a normal karyotype, and some - a pathological one.

This kind of anomaly occurs in 3-5% of cases of the disease. It has a positive prognosis, since healthy cells partially compensate for the genetic disorder. Such children are born with external signs of the syndrome and developmental delay, but their survival rate is much higher. They are less likely to have internal pathologies incompatible with life.

Symptoms of mosaic Down syndrome

An abnormal genetic feature of an organism that occurs with an increase in the number of chromosomes has a number of external and internal signs. Symptoms of mosaic Down syndrome are manifested by a lag in mental and physical development.

The main physical symptoms of the disease are:

Small and slow growth.

Muscle weakness, reduced strength function, abdominal weakness (sagging abdomen).

Short, thick wrinkled neck.

Short limbs and large distance between thumb and forefinger.

A specific skin fold on the palms of children.

Low set and small ears.

Distorted shape of the tongue and mouth.

Crooked teeth.

The disease causes a number of developmental and health problems. First of all, these are cognitive retardation, heart defects, problems with teeth, eyes, back, hearing. Propensity to frequent infectious and respiratory diseases. The degree of manifestation of the disease depends on congenital factors and the correct treatment. Most toddlers are learning, despite mental, physical and mental retardation.

First signs

Mosaic Down syndrome has less severe symptoms than the classic form of the disorder. The first signs can be seen on an ultrasound scan at 8-12 weeks of pregnancy. They are manifested by an increase in the collar zone. But ultrasound does not give a 100% guarantee of the presence of the disease, but allows you to assess the likelihood of malformations in the fetus.

The most characteristic external symptoms are, with their help, doctors presumably diagnose the pathology immediately after the birth of the baby. The defect is characterized by:

Slanting eyes.

"Flat" face.

Short-headedness.

Thickened cervical skin fold.

Lunate fold at the inner corner of the eyes.

Further examination reveals the following problems:

Decreased muscle tone.

Increased joint mobility.

Deformation of the chest (keeled, funnel-shaped).

Broad and short bones, flat nape.

Deformed ears and wrinkled nose.

Small arched sky.

Pigmentation along the edge of the iris.

Transverse palmar fold.

In addition to external symptoms, the syndrome also has internal disorders:

Congenital heart defects and other disorders of the cardiovascular system, anomalies of large vessels.

Respiratory system pathologies caused by structural features of the oropharynx and large tongue.

Strabismus, congenital cataract, glaucoma, hearing impairment, hypothyroidism.

Gastrointestinal disorders: intestinal stenosis, atresia of the anus and rectum.

Hydronephrosis, renal hypoplasia, hydroureter.

The above symptoms require constant treatment to maintain the normal state of the body. It is congenital defects that are the reason for the short life of downs.

External signs of the mosaic form of Down syndrome

In most cases, the external signs of the mosaic form of Down syndrome appear immediately after birth. Due to the high prevalence of gene pathology, its symptoms have been studied and described in detail.

Changes in the 21st chromosome are characterized by the following external signs:

Abnormal structure of the skull.

This is the most noticeable and pronounced symptom. Normally, babies have a larger head than adults. Therefore, any deformities are visible immediately after birth. Changes concern the structure of the cranium and facial skull. The patient has a disproportion in the region of the bones of the crown. There is also a flattening of the occiput, a flat face, and pronounced ocular hypertelorism.

A person with this disease resembles a representative of the Mongoloid race. Such changes appear immediately after birth and persist throughout life. In addition, it is worth abolishing strabismus in 30% of patients, the presence of a skin fold at the inner corner of the eyelid and pigmentation of the iris.

Congenital defects of the oral cavity.

This kind of disorder is diagnosed in 60% of patients. They create difficulties in feeding the baby by slowing down his growth. A person with the syndrome has a changed surface of the tongue due to a thickened papillary layer (grooved tongue). In 50% of cases, there is a gothic palate and violations of the sucking reflex, a half-open mouth (muscle hypotonia). In rare cases, cleft palate or cleft lip abnormalities are observed.

This violation occurs in 40% of cases. Underdeveloped cartilage forms an irregular pinna. Ears can be protruded in different directions or located below eye level. Although the defects are cosmetic, they can cause serious hearing problems.

Accessory skin folds.

Occur in 60-70% of patients. Each fold of skin is caused by underdeveloped bones and their irregular shape (the skin is not stretched). This external symptom of trisomy manifests itself as excess skin on the neck, thickening in the elbow joint and a transverse fold in the palm of the hand.

Pathologies of the development of the musculoskeletal system

They arise due to a violation of the intrauterine development of the fetus. The connective tissue of the joints and some bones do not have time to fully form before birth. The most common abnormalities are short neck, increased joint mobility, short limbs and misshapen fingers.

Deformation of the chest.

This problem is associated with underdevelopment of bone tissue. In patients, there is a deformation of the thoracic spine and ribs. Most often, they diagnose a bulging sternum above the surface of the chest, that is, a keeled shape and deformation, in which there is a funnel-shaped depression in the solar plexus area. Both disorders persist as they grow older and older. They provoke disturbances in the structure of the respiratory system and the cardiovascular system. Such external symptoms indicate a poor prognosis of the disease.

The main feature of the mosaic form of Down syndrome is that with it, many of the above symptoms may be absent. This complicates the differentiation of pathology with other chromosomal abnormalities.

The syndrome has several types, consider them:

Mosaic - not all cells of the body contain an extra chromosome. This type of disease accounts for 5% of all cases.

Family - occurs in 3% of patients. Its peculiarity is that each of the parents has a number of deviations that are not expressed externally. During fetal development, part of the 21st chromosome attaches to another, making it a pathological carrier of information. Parents with this defect have children with the syndrome, that is, the anomaly is inherited.

Duplication of part of chromosome 21 is a rare type of disease, the peculiarity of which is that chromosomes are not able to divide. That is, additional copies of chromosome 21 appear, but not all genes. Pathological symptoms and external manifestations develop if fragments of rut are duplicated, which determine the clinical picture of the defect.

Complications and consequences

Chromosomal mosaicism causes consequences and complications that negatively affect the state of health and significantly worsen the prognosis of the disease.

Consider the main dangers of trisomy:

Pathologies from the cardiovascular system and heart defects. About 50% of patients have birth defects that require surgical treatment at an early age.

Infectious diseases - defects in the immune system provoke increased sensitivity to various infectious pathologies, especially colds.

Obesity - People with the syndrome are more likely to be overweight than the general population.

Diseases of the hematopoietic system. Downs are more likely to suffer from leukemia than healthy children.

Short life expectancy - the quality and duration of life depends on the severity of congenital diseases, the consequences and complications of the disease. Back in the 1920s, people with the syndrome did not live to be 10 years old, today the age of patients reaches 50 years or more.

Dementia - Dementia and persistent cognitive decline is associated with an abnormal protein buildup in the brain. Symptoms of the disorder occur in patients under 40 years of age. This disorder is characterized by a high risk of seizures.

Cessation of breathing during sleep - apnea is associated with abnormal structure of soft tissues and skeleton, which are susceptible to airway obstruction.

In addition to the complications described above, trisomy is characterized by thyroid problems, weak bones, poor vision, hearing loss, early menopause, and intestinal obstruction.

Diagnostics of the mosaic Down syndrome

It is possible to identify genetic pathology even before birth. Diagnosis of mosaic Down syndrome is based on the study of the karyotype of blood and tissue cells. In the early stages of pregnancy, a chorionic biopsy is performed to detect signs of mosaicism. According to statistics, only 15% of women who find out about genetic abnormalities in a child decide to leave him. In other cases, premature termination of pregnancy is indicated - abortion.

Consider the most reliable methods for diagnosing trisomy:

Biochemical blood test - blood is taken from the mother for research. Body fluid is assessed for β-hCG and plasma protein A. In the second trimester, another assay is performed to monitor β-hCG, AFP and free estriol levels. Decreased levels of AFP (a hormone produced by the liver of the fetus) are highly likely to indicate a disease.

Ultrasound examination - performed in every trimester of pregnancy. The first allows you to identify: anencephaly, cervical hygroma, to determine the thickness of the collar zone. The second ultrasound scan makes it possible to track a heart defect, anomalies in the development of the spinal cord or brain, disorders of the gastrointestinal tract, hearing organs, and kidneys. In the presence of such pathologies, termination of pregnancy is indicated. The last study, carried out in the third trimester, can reveal minor disorders that can be corrected after childbirth.

The studies described above allow one to assess the risk of having a baby with the syndrome, but they do not provide an absolute guarantee. At the same time, the percentage of erroneous results of diagnostics carried out during pregnancy is small.

Diagnosis of genomic pathology begins during gestation. Tests are performed early in pregnancy. All tests for trisomy are called screenings or screenings. Their dubious results allow one to suspect the presence of mosaicism.

First trimester - up to 13 weeks, an analysis is carried out for hCG (human chorionic gonadotropin) and PAPP-A protein, that is, substances secreted only by the fetus. In the presence of the disease, hCG is increased, and the level of PAPP-A is lowered. With these results, amnioscopy is performed. Tiny particles of chorion are extracted from the uterine cavity of the pregnant woman through the cervix.

Second trimester - tests for hCG and estriol, AFP and inhibin-A. In some cases, a study of genetic material is carried out. For its collection, a puncture of the uterus is made through the abdomen.

If, according to the results of the tests, a high risk of trisomy is established, then the pregnant woman is prescribed a consultation with a geneticist.

Instrumental diagnostics

To identify intrauterine pathologies in the fetus, including mosaicism, instrumental diagnostics are shown. If Down's syndrome is suspected, screenings are done throughout pregnancy, as well as ultrasound to measure the thickness of the back of the fetal neck.

The most dangerous method of instrumental diagnostics is amniocentesis. This is a study of amniotic fluid, which is carried out for a period of 18 weeks (a sufficient volume of fluid is required). The main danger of this analysis is that it can lead to infection of the fetus and mother, rupture of the membranes and even miscarriage.

Differential diagnosis

The mosaic form of changes in chromosome 21 requires careful research. Differential diagnosis of Down syndrome is carried out with the following pathologies:

Shereshevsky-Turner syndrome
Edwards syndrome
De La Chapelle syndrome
Congenital hypothyroidism
Other forms of chromosomal abnormalities

In some cases, sex chromosome XX / XY mosaicism leads to true hermaphroditism. Differentiation is also necessary for mosaicism of the gonads, which are a particular case of organ pathology that occurs at the later stages of embryonic development.

Who to contact?

Treatment of mosaic Down syndrome

Therapy for chromosomal diseases is not possible. Treatment for mosaic Down syndrome is lifelong. It is aimed at eliminating malformations and concomitant diseases. A person with this diagnosis is under the control of such specialists: pediatrician, psychologist, cardiologist, psychiatrist, endocrinologist, ophthalmologist, gastroenterologist and others. All treatment is aimed at social and family adaptation. The task of the parents is to teach the baby full self-care and contact with others.

Downs treatment and rehabilitation consists of the following procedures:

Massages - the muscular system of both an infant and an adult with this syndrome is underdeveloped. Special gymnastics helps to restore muscle tone and maintains them in normal condition. Particular attention is paid to hydromassages. Swimming and water gymnastics improve motor skills and strengthen muscles. Dolphin therapy is popular, when the patient swims with dolphins.
Nutritional Consultation - Trisomy patients have overweight problems. Obesity can provoke various disorders, the most common are disorders of the cardiovascular system and the digestive tract. The dietitian gives recommendations on nutrition and, if necessary, prescribes a diet.
Speech therapist consultations - for mosaicism, as well as for other types of syndrome, disorders in the development of speech are characteristic. Classes with a speech therapist will help the patient to express their thoughts correctly and clearly.
A special training program - children with the syndrome are lagging behind their peers in development, but they are learnable. With the right approach, a child can master basic knowledge and skills.

Patients are shown restorative therapy, psychostimulants, neurometabolic and hormonal drugs are often prescribed. It also requires regular intake of vitamins. All drug therapy is combined with medical and pedagogical correction. Congenital pathologies and complex diseases require surgical intervention.

Prophylaxis

Today, there are no reliable methods for preventing genetic diseases. Prevention of mosaic Down syndrome consists of the following recommendations:

Timely treatment of any disease and a healthy lifestyle. The increased activity improves blood circulation, protecting the eggs from oxygen starvation.
Proper nutrition and normal weight. Vitamins, minerals and other nutrients not only strengthen the immune system, but also maintain hormonal balance. Excess weight or excessive thinness upsets the hormonal balance, and provoke disruptions in the maturation and development of germ cells.
Preparing for pregnancy. A couple of months before the planned conception, it is necessary to consult a gynecologist and start taking vitamin and mineral complexes. Particular attention should be paid to folic acid, vitamins B and E. They normalize the functioning of the genitals and improve metabolic processes in the germ cells. Do not forget that the risk of giving birth to a child with deviations increases in couples where the expectant mother is over 35 years old and the father is over 45.
Prenatal diagnosis. Analyzes, screenings and a number of other diagnostic procedures performed during pregnancy can identify serious fetal abnormalities and make a decision about further gestation or abortion.

But even the implementation of all preventive measures cannot give a 100% guarantee of the birth of a completely healthy baby. Trisomy is an accidental genetic abnormality that no woman is immune from.

Mosaic Down syndrome has a more positive outcome, in contrast to the classic form of pathology. The prognosis is due to the fact that healthy cells partially compensate for the genetic defect. But the child will still have external signs of trisomy and its characteristic developmental lag. But the survival rate of such patients is much higher, they are less likely to have developmental defects that are incompatible with life.

Famous people with mosaic Down syndrome

Changes in chromosome 21 lead to irreversible consequences that cannot be treated. But, despite this, among those born with trisomy there are artists, musicians, writers, actors and many other accomplished personalities. Famous people with the mosaic form of Down syndrome boldly declare their illness. They are a vivid example of the fact that if you want, you can cope with any problem. Such celebrities have a genomic violation:

Jamie Brewer is an actress best known for her role in the American Horror Story series. The girl not only acts in films, she is also a model. Jamie participated in the Mercedes-Benz Fashion Week in New York.

Raymond Hu is a young artist from California, USA. The peculiarity of his paintings is that he draws them according to the old Chinese technique: on rice paper, watercolors and ink. The guy's most popular works are animal portraits.

Pascal Duquenne is an actor, winner of the Silver Prize at the Cannes Film Festival. He became famous for his role in the film Jaco van Dormel's "Eighth Day".

Ronald Jenkins is an internationally renowned composer and musician. His love for music began with a gift - a synthesizer he received as a child for Christmas. Today, Ronald is considered a genius of electronic music.

Karen Hafnii - teaching assistant, athlete. The girl is engaged in swimming and participated in the marathon on the English Channel. She became the first person with mosaicism to swim 15 km in a water temperature of + 15 ° C. Karen has her own charitable foundation, which represents the interests of people with chromosomal disorders.
Tim Harris is a restaurateur, owner of "the friendliest restaurant in the world." In addition to the delicious menu, Tim's place offers free hugs.

Miguel Tomasin is a member of the Reynols group, drummer, guru of experimental music. The guy performs both his own songs and covers of famous rock musicians. Engaged in charity work, performs in centers and at concerts to support sick children.

Bohdan Kravchuk is the first person in Ukraine with Down syndrome who entered the university. The guy lives in Lutsk, is fond of science, has many friends. Bohdan entered the Lesya Ukrainka East European National University at the Faculty of History.

As practice shows and real examples, despite all the complications and problems of gene pathology, with the right approach to its correction, you can raise a successful and talented child.

The human genome is made up of 46 chromosomes arranged in 23 pairs. Of these, 44 are somatic, that is, they are responsible for the structure and characteristics of the entire human body. And only one pair of chromosomes carries information about his gender and determines the differences between men and women.

Both sex chromosomes of women are the same in structure and are designated in genetics by the letter X. And in men, this pair is represented by different chromosomes - X and Y.

Klinefelter's syndrome: karyotype

Klinefelter's syndrome is such a change in the chromosome set, in which one or more X chromosomes are added to the XY karyotype. Accordingly, only carriers of the Y chromosome, that is, men, suffer from this disease.

A person with Klinefelter's syndrome has a chromosome set that differs from the norm by only one pair of chromosomes - just the one that is responsible for sexual characteristics.

For clarity, we tried to depict the karyotype of a patient with Klinefelter's syndrome in the figure:

Variety of options

Klinefelter's syndrome can be represented by different cytogenetic variants, which also determine the difference in the severity of symptoms and tactics of patient management.

The origins of the disease

The causes of the appearance of Klinefelter's syndrome lie in the nondisjunction of chromosomes during cell division.

According to statistics, a third of patients receive an extra chromosome from the father's sperm, and the other two-thirds from the mother's egg.

Risk factors for the appearance of this disease are traditionally considered viral infections, disturbances in the functioning of the immune systems of the parents and the late age of the mother.

Establishing diagnosis

When the doctor can rely on the level of hormones in the blood test, the results of a spermogram, ultrasound of the scrotum and testicular biopsy. But the diagnosis can only be finally confirmed by the results of a blood test for the karyotype characteristic of Klinefelter's syndrome.

For this, leukocytes isolated from the blood are placed in a nutrient medium and then examined for the presence of a chromosomal abnormality in their DNA.

A modern blood test allows you to accurately differentiate any genetic disease and with a 100% probability to distinguish, for example, a syndrome from a syndrome even at the stage of pregnancy. For this, the cells of the embryo or amniotic fluid are taken.

In developed countries, many chromosomal abnormalities, including Klinefelter's syndrome, are detected even during pregnancy, since women planning motherhood at a later age try to eliminate the risk of having a sick baby as much as possible.

In the United States, in the presence of such an anomaly in the unborn child, about half of women prefer to terminate the pregnancy. In Russia, karyotyping analysis is not a widespread practice; it is carried out only if, according to the results of screening a pregnant woman, there are suspicions about the presence of genetic abnormalities in the fetus.

In many cases, the syndrome is detected much later.- when characteristic signs occur during growing up.

Despite the advances in modern medicine, about half of the cases of Klinefelter's syndrome remain generally unrecognized, although patients go to doctors with complaints of enlarged mammary glands, erectile dysfunction and infertility.

Karyotype analysis for the determination of Down, Klinefelter, Turner syndromes

Down, Klinefelter and Turner syndromes are the most common chromosomal abnormalities. Therefore, from a prophlactic point of view, it is important, through karyotyping, to diagnose these diseases as early as possible and, in some cases, to carry out prenatal diagnostics.

Down syndrome (trisomy 21) - one of the forms of genomic pathology, in which most often the karyotype is represented by 47 chromosomes instead of the normal 46, since the chromosomes of the 21st pair, instead of the normal two, are represented by three copies. There are two more forms of this syndrome: translocation of chromosome 21 to other chromosomes (more often by 15, less often by 14, even less often by 21, 22 and Y chromosomes) - 4% of cases, and a mosaic variant of the syndrome - 5%. Down's syndrome is not a rare condition - on average, there is one case in 700 births; at the moment, due to prenatal diagnosis, the frequency of births of children with Down syndrome has decreased to 1 in 1100. In boys and girls, the anomaly occurs with the same frequency. The likelihood of having children with Down syndrome increases with the age of the mother (after 35 years) and, to a lesser extent, with the age of the father. According to the literature, the frequency of nondisjunction of the 21st chromosome in spermatogenesis, as well as in oogenesis, increases with age. After the accident at the Chernobyl nuclear power plant, an increase in the number of congenital abnormalities was found in various regions of Belarus between 1986 and 1994, but it was approximately the same in both polluted and clean areas. no trend towards an increase in morbidity was observed.

Klinefelter's syndrome occurs in 1 in 500 boys. Patients with the classic variant of the syndrome have a 47, XXY karyotype. Other karyotypes are also possible, and in 10% of patients mosaicism 46, XY / 47, XXY is detected, there are also more rare karyotypes: 48, XXXY; 49, XXXXY; 48, XXYY; 49, XXXYY. The syndrome usually manifests itself in adolescence as a delay in puberty. The penis and testicles are reduced, the physique is eunuchoid, infertility, gynecomastia, moderate mental retardation and antisocial behavior are characteristic. Sometimes testicular hypoplasia is the only symptom of the disease in apparently healthy men. Patients are prone to diabetes mellitus, thyroid disease and breast cancer. The presence of at least two X chromosomes and one Y chromosome in a karyotype is the most common cause of primary hypogonadism in men. Treatments for infertility in Klinefelter's syndrome have not yet been developed. Testosterone replacement therapy is usually started at the age of 11-14; with androgen deficiency, it significantly accelerates the formation of secondary sexual characteristics. In adult patients, on the background of testosterone treatment, libido increases. Gynecomastia may require surgery. Psychotherapy contributes to the social adaptation of patients with Klinefelter's syndrome and patients with other sex chromosome abnormalities.

Shereshevsky-Turner syndrome or gonadal dysgenesis - This is a violation of the development of the gonads caused by an abnormality of the sex chromosomes. During the division of the sex cells of the parents, the divergence of the sex chromosomes is disrupted, as a result of which, instead of the normal number of X-romosomes (and normally a woman has two of them), the embryo receives only one X-chromosome. The set of chromosomes is incomplete. This syndrome occurs with a frequency of one in three thousand girls born. The development of the gonads is disrupted already in the early period of development of the embryo. During puberty, secondary sexual characteristics do not develop (the mammary glands are underdeveloped, hairiness on the pubis and in the armpits is not expressed). There is no menses. One third of patients have malformations of other organs, as well as diabetes mellitus, inflammatory diseases of the colon, goiter and thyroiditis, gastrointestinal bleeding.

X0 syndrome - Shereshevsky-Turner syndrome. Syndrome XXY - Klinefelter syndrome in neurology

X0 syndrome due to a lack of genetic material localized on the X chromosome. First described by N. A. Shereshevsky in 1925, and in 1938 - 1. Turner. It occurs with a frequency of 1: 2500-1: 3000 newborn girls.

Pathological studies indicate the underdevelopment of the gonads, which are either completely absent, or have the form of connective tissue cords with remnants of ovarian tissue and interstitial cells. Often, malformations of the cardiovascular system (coarctation of the aorta, stenosis of the pulmonary artery, defect of the interventricular septum, non-closure of the botalle duct), gastrointestinal tract, urinary system (cystic kidney, horseshoe-shaped kidneys) are found.

Diagnose the syndrome is possible already in the neonatal period. Children are born with a low weight and small stature, moderate swelling of the hands and feet can be observed for several months; low hair growth on the neck, short neck with pterygoid folds extending from the mastoid processes to the shoulders, or excessive mobility of the skin on the neck. Other developmental anomalies include epicant, fused eyebrows, ptosis, lagophthalmos or exophthalmos, hypertelorism, microphthalmos, eyelid colobomas, wide flat chest imitating wide-spaced nipples, vertebral fusion, clinodactyly, valgus curvature of the feet of the body and anomalies of bite , osteoporosis.

With ophthalmological examination cloudy opacities and decreased sensitivity of the cornea, pallor of the optic nerve, narrowing of the arteries in the fundus, microphthalmos, cataracts are detected.

In neurological status usually no abnormalities are observed, with the exception of general muscle hypotension. Mental development at an early age is normal or its pace is somewhat slowed down.

With dermatoglyphic research changes in the skin patterns of the fingers and palms are revealed. An increase in the frequency of ulnar loops on the thumb and forefinger is usually found. Distal axial triradius occurs in 50% of patients with Shereshevsky-Turner syndrome. More often than in healthy people, there is a transverse fold of the palm and a single fold on the V finger. Palmar patterns are very large distal loops or curls with a large ridge score.

The complex of these symptoms is an indication for the study of scrapings of the oral mucosa for sex chromatin. About 80% of patients with Shereshevsky-Turner syndrome are chromatin-negative, their karyotype is 45, XO. With deletions of Xq-, Xp-, as well as with the circular X chromosome, XO / XX mozapcism, the clinical signs are less pronounced than with the XO syndrome. In scrapings from the mucous membrane, small Barr bodies are determined in fewer numbers than in normal girls.

Diagnosis verified by examining the karyotype of peripheral blood lymphocytes.

In young years syndrome should be differentiated from hypotrophy of another etiology, hypothyroidism, congenital malformations of a non-chromosomal nature; with pronounced redundancy of the skin on the neck - from cutis laxa and Ehlers-Danlos syndrome.

Treatment of Shereshevsky-Turner syndrome symptomatic at an early age. In order to stimulate mental and motor development, Cerebrolysin, Aminolone, Acefen, Prephysone, B vitamins, massage, and physiotherapy exercises are used.

XXY Syndrome (Klinefelter Syndrome)

Syndrome due to trisomy of the sex chromosomes due to the presence of an additional X chromosome. It occurs with a frequency of 1: 400-500 newborn boys. Described in 1942 by A. Klinefelter et al.

Pathomorphologically characterized primary gonadal dysgenesis. Their histological examination reveals a narrowing or obliteration of the seminiferous tubules, hyaline sclerosis, proliferation of Leydig cells. Non-lyterated tubules are filled with degenerative sertolium cells.

A characteristic feature syndrome in early childhood, there is a decrease in the size of the testicles and a change in their consistency (denser or, conversely, softer). Already in the neonatal period, attention is drawn to the features of the physique of the child - disproportionately long legs and arms, a narrow chest. Mental development is usually normal. In a number of patients, eye changes are described in the form of retinal pigment degeneration and colobomas of the uveal tract.

Boys with Klinefelter syndrome chromatin-positive. On dermatoglyphs, there may be a displacement of the axial triradius, an increase in the angle atd, an increase in the frequency of arcs on the fingers, a tendency to a decrease in the ridge count.

Diagnosis verified by examining the karyotype in peripheral blood lymphocytes, in which, in most cases, 47 chromosomes are detected due to an additional X chromosome. However, the number of X chromosomes can be more than 2. In such patients, all the symptoms of the disease are more pronounced, mental retardation is necessarily noted, the deeper, the more X chromosomes in the karyotype, gigantism and acromegaly can be.

At an early age, the syndrome diagnosed only with a screening study of sex chromatin.

Treatment at an early age, they are carried out only in cases of mental retardation. Prescribe drugs that stimulate the function of the central nervous system (aminolone, cerebrolysin, vitamins of group B), conduct speech therapy and pedagogical classes, purposefully forming the higher cortical functions.

XYY syndrome. The 47, XYY karyotype occurs among newborn boys with a frequency of 1: 250-500 and is most often not accompanied by a pathological phenotype. At an early age, developmental features are not found. May be an accidental karyoloptic find.

Polysomy X syndrome. Most often it occurs in the form of trisomy X (47, XXX) and may not be accompanied by a pathological phenotype. When the number of X chromosomes is more than 3, mental retardation and dysgenesis of the gonads are characteristic, the more pronounced the more additional X chromosomes.

Possible karyotypes of Down syndrome. Down syndrome karyotype

Patau syndrome: karyotype and general information

Brief historical background

The reasons for the development of the disease

Types of pathology

Are there risk factors? What can provoke the appearance of a mutation?

Symptoms of pathology during pregnancy

Patau syndrome: photos and distinctive signs

Pathology from other organ systems

Diagnostic measures

Is there an effective treatment?

Forecasts for small patients

Down syndrome causes

Why does the disease occur

Video: Down syndrome

Symptoms of the disease

Diagnosis of the disease

Treatment and prognosis of the disease

Video: children with Down syndrome in schools and kindergartens

Down Syndrome. Karyotype and phenotypic characteristics

Complete trisomy of chromosome 21 is a genetic cause of Down's disease. Cognitive level of newborns with this disease. Hearing, vision, sleep apnea, cardiovascular health. Immunological aspects and dysfunction of the thyroid gland.

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