Thea Saxa treatment. Tay Sachs disease is a hereditary disease

Date: 04.03.2020

Tay-Sachs disease has several names: infantile gangliosidosis or early infantile idiocy amavrotic.

This disease belongs to hereditary diseases. nervous system and is quite rare.

The disease got its name in honor of the two doctors who discovered it - Warren Tey (an ophthalmologist from Britain) and Bernard Sacks (a neurologist from America).

The development of the disease depending on age

There are three forms of the disease:

child form amaurotic family idiocy, in which babies experience a sharp deterioration in physical and mental health 6 months after birth (blindness, deafness develops rapidly, the child loses the ability to swallow);
teenage form, in which there is also a violation of swallowing, severe speech disorders, instability appears when walking, paralysis occurs;
adult form which develops between the ages of 25 and 30. To the symptoms listed above is added schizophrenia, which occurs in the form of psychosis.

Causes of the disease

Causes of the disease rooted in genetic disorders that occur in ganglioside metabolism. These special lipids, exceeding 300 times the norm, are concentrated in gray matter brain.

Accumulation also occurs in the liver and spleen. The disease is based on a deficiency of one of the types of enzymes that affect lipid metabolism (hexosaminidase A).

The disease occurs in the ratio: 1 in 250,000. Basically, this disease affects the population of ethnic groups, for example, the French, whose place of residence is Canada.

Jews of Eastern Europe are also susceptible to the disease, in which the incidence is higher - 1 per 4,000 people.

This disease develops in the baby who got two genes with a defect, that is, the disease is inherited in an autosomal recessive manner. What does it mean?

A child inherits genes from the father and from the mother in the same amount. If one or both chromosomes from a pair are affected, then they speak of the occurrence genetic disease. In people with Tay-Sachs disease, both chromosomes in a pair are defective.

This disorder is called an autosomal recessive disorder. If one of the parents has a defective gene, the baby will be healthy, but with a 50% chance it will be a carrier, which jeopardizes the health of his heirs in the future. In the presence of a gene with a defect in both parents, three scenarios are possible.

A child with a probability of 25% can be born healthy and will not be a carrier of the gene. In 50% of cases, the baby will be a carrier of the defective gene, but will be born healthy. In 25% of cases, a baby can get two genes with a defect, and he will be born with Tay-Sachs disease.

Risk factors

Driving force for development this disease is the gradual accumulation in the nervous system of gangliosides - substances that affect the normal functioning of the cells of the nervous system.

All sick children have a damaged gene responsible for the complete synthesis of hexosaminidase enzymes.

The child's body congenital disease cannot continuously process fatty substances, so they accumulate and then are deposited in the brain.

This results in the activity nerve cells is blocked and severe consequences for the whole organism occur. In the same body healthy child gangliosides are constantly being synthesized and broken down.

Main symptoms

Pathology is diagnosed in babies at the age of about six months, since up to four to five months the child develops quite normally, like all children of this age.

initial stage

The first symptoms of Tay Sachs disease are that the child loses contact with the outside world, his gaze is constantly focused in one direction, the baby does not want anything, he becomes apathetic, he has no reaction to objects, sounds, familiar faces.

He has an increased reaction only to loud and sharp sounds. Even when the baby looks quite healthy, parents and relatives often notice that the child shudders sharply with his whole body at loud auditory stimuli.

A complex of disorders that manifest increased fatigue, sleep disturbance, mood instability are called one term -.

Friedreich's hereditary ataxia causes serious disorders of the nervous system - causes, symptoms and pathologies.

Development of the disease

The second stage of the disease is a regression in the development of the child: the acquired skills are lost, he refuses to crawl, sit, becomes passive, toys do not cause any interest, mental retardation occurs, at the same time the size of the head increases significantly, the baby begins to lose sight, and often hearing.

At a later stage between the first year of life and the second year of life, the baby is more likely to experience seizures, manifested in the form of convulsions and paralysis.

Babies do not gain weight, but rapidly lose it. With this development of the disease, the child rarely survives to the age of five.

Signs of illness in adults

The adult form is very rare and occurs in patients in their 20s and 30s. It usually does not have a fatal outcome.

The disease manifests itself in gait disturbance and rapid deterioration of neurological functions. With such a disease, an adult can live after diagnosis for 10 to 15 years.

Diagnosis of the disease

Before determining the diagnosis, the doctor examines the results of the research, asks parents in detail about clinical manifestations, finds out whether there were cases of this disease in the family.

The doctor will definitely refer you to an ophthalmologist for examination, since a typical manifestation of the disease is the location of a red spot on the retina of the eye, which can be determined using an ophthalmoscope.

There are also changes in the nipple optic nerve: it will atrophy.

It can not be cured, it is necessary to support

Treatment of Tay-Sachs disease must begin before the onset of neurological signs. Use blood transfusion, plasma.

There are no drugs and specific methods that cure Tay-Sachs disease.

The doctor prescribes only drugs that can support the functioning of the liver, as well as in without fail various vitamins and anticonvulsants.

The latter are often ineffective against seizures that occur with this disease. Health care It consists in a simple relief of the symptoms of the manifestation of the disease, but if we are talking about a late form, then to a delay in the development of the disease.

The prognosis for this disease is unfavorable.

Disease prevention

To prevent the disease, spouses who want to have children must be screened for the presence of the gene for this disease, if at least one of the spouses had cases of Tay-Sachs disease in the family.

If such a gene is found in both spouses, then they are categorically not recommended to conceive children. It happens that during the examination a woman is already carrying a child, then a special procedure is prescribed to identify the defective gene in the child - amniocentesis.

For this, amniotic fluid obtained by taking a puncture of the amniotic membrane is subjected to laboratory testing. If the defective gene is found, the pregnancy must be terminated.

If the future parents have accurate information that they are carriers of the defective gene, and pregnancy has already occurred, then it is necessary to undergo a screening test at the twelfth week.

To conduct a study, doctors take blood from the placenta to find out if inherited future baby mutant genes.

Future parents need to be responsible for their own health and the health of their future children and follow all the recommendations of doctors.

Prenatal diagnosis during each pregnancy enables a married couple to give birth to healthy children.

Tay-Sachs disease hereditary disease. Characteristic:

impaired motor skills;
signs of backwardness;
motor impairment;
brain disorders

Children in certain period develop within the normal range. Then brain damage. Life span is five years.

Description of pathology by doctors. A rare type of disease.

Tay-Sachs disease - etiology

A rare percentage of the incidence of hereditary nature. The risk group is ethnic. Peoples by pathology:

French people;
Jews

The type of heredity is recessive. The child is healthy with the development of the pathogenic gene in one parent. However, carrier status will be determined.

If both parents are affected, the situation is as follows:

25 percent for the birth of a healthy child;
50 percent for determination of carriage;
25 percent of having an abnormal gene

The accumulation of substances is the basis of pathology. The vital activity of nerve cells is the goal of the substance. Characteristics of the sign of gangliosides:

splitting process;
the process of maintaining balance;
decay

The action of the ganglioside group:

brain deposits;
blocking;
severe symptoms

Tay-Sachs disease - symptoms

The period of defeat is six months. Initial symptoms:

violation of social contact;
gaze;
apathy;
sonic response

Late signs:

loss of skills
movement disorder;
developmental delay;
blindness

The following features are downgraded:

nutritional functions;
drinking functions;
ability to move;
ability to make sounds

The head is large. There may be seizures. Lethal outcome at five years.

Symptoms by age:

visual impairment, perception of loud sound;
signs of hypotension, decreased activity;
development of retardation, blindness, seizure

Tay-Sachs disease - clinic

Clinical signs of the disease:

loss of speech functions;
decreased motility;
decreased coordination;
the psyche is broken;
hearing loss;
decreased vision

Outcomes of these signs:

disability;
fatal outcome

To others clinical signs include:

signs of substance deficiency;
progressive signs;

Diagnosis of Tay-Sachs disease

The appearance of a burgundy spot on the eyes is the main syndrome. This is a sign of accumulation of matter. Carry out diagnostics:

neuron detection;
screening;

Tay-Sachs disease - therapy

There are no cures for the disease. Life expectancy age is five years. Therapy methods:

using a feeding tube;
skin care;
nutritious diet

Doesn't help with cramps anticonvulsants. Prevention methods:

genetic research;
survey of married couples

If the gene is found, pregnancy is excluded. In the presence of pregnancy, the process of amniocentesis is carried out.

Lifespan

As mentioned above, life expectancy is on average up to five years. This is associated with the development of severe symptoms. Also, the cause is a different lesion.

Mental disorders, developmental delays lead to progressive pathology. Progressive pathology, in turn, leads to death, as well as disability. The child loses previous skills.

This means that the development of the child is suspended. Treatment includes general care. This pathology impossible to cure. More often the outcome is unfavorable.

Tay-Sachs disease (first part)

Tay-Sachs disease (TSD)(also known as GM2 gangliolipidosis, hexosaminidase deficiency, or early infantile amaurotic idiocy ) - this, which causes a progressive deterioration in the mental and physical abilities of the child. The first signs of the disease usually appear around 6 months of age. The disorder usually results in the death of the affected individual around the age of 4 years.

The disease is caused by a specific genetic defect. If a child is affected by BPS, then this means that he has one copy of the defective gene from each parent. The disease manifests itself when a dangerous amount of gangliosides accumulates in the nerve cells of the brain, which results in premature death these cells. To date, there are no effective drugs or other treatments for this disease. BPS is quite rare compared to other recessive diseases, such as sickle cell anemia, which are more common.

The disease is named after the British ophthalmologist Warren They (who first described a red spot on the retina in 1881) and an American neurologist Bernard Sachs , who worked at Mount Sinai Hospital in New York (he described the cellular changes that occur in BTS and in 1887 noted an increase in the incidence of the disease among Ashkenazi Jews, who are ethnically similar to Eastern Europe).

Studies of the disease that were conducted at the end of the twentieth century showed that Tay-Sachs disease is caused by gene HEXA , which is located on . To date, a large number of HEXA mutations have already been identified, and new studies provide information about new mutations. These mutations are very common in several populations. The number of carriers among French Canadians (living in the southeast of Quebec) is almost the same as among Ashkenazi Jews, however, the mutations that cause BTS among these ethnic groups are different. Many members of the Cajun ethnic group (who today live in southern Louisiana) carry the same mutations that are most common among Ashkenazi Jews. As already mentioned, these mutations are very rare and do not occur among genetically isolated populations. That is, the disease can only arise from the inheritance of two independent mutations in the HEXA gene.

Classification and symptoms

Tay-Sachs disease is classified according to different forms, depending on the time of occurrence neurological symptoms. The form of the disease reflects the variant of the mutation.

Children's form of Tay-Sachs disease.

During the first six months after birth, babies develop normally. But, after the nerve cells accumulate gangliosides and thus stretch, there is a continuous deterioration in the mental and physical abilities of the patient. The child becomes blind, deaf, and cannot swallow. Muscles begin to atrophy, resulting in paralysis. Death usually occurs before the age of four.

Adolescent form of Tay-Sachs disease.

This form of the disease is extremely rare and usually manifests itself in children aged 2 to 10 years. They develop cognitive-motor problems, problems with speech (dysarthria), swallowing (dysphagia), unsteady gait (ataxia), and spasticity occurs. Patients with juvenile BPS usually die between the ages of 5 and 15 years.

The adult form of Tay-Sachs disease (LOTS).

A rare form of the disorder, known as adult-onset Tay-Sachs disease or late-onset Tay-Sachs disease (LOTS), occurs in patients in their 20s and 30s. LOTS is often misdiagnosed and is usually not fatal. It is characterized by gait disturbance and progressive deterioration of neurological function. Symptoms of this form, which occurs in adolescence or early adulthood, are: problems with speech and swallowing, unsteady gait, spasticity, decreased cognitive skills, the onset of mental illness, in particular schizophrenia in the form of psychosis.

Even before 1970s and 80s When the molecular nature of the disease became known, the adult and adolescent forms were almost never considered as forms of Tay-Sachs disease. BTS that occurs in adolescence or adulthood is often diagnosed as another neurological disorder, such as Friedreich's ataxia. People affected by BPS in adulthood often use a wheelchair to get around, but many of them live almost full lives, but only if they adapt to the physical and psychiatric complications (which can be controlled with medication).

Journalist Janet Silver Ghent) described the experience of Vera, a girl from a Russian-Jewish family who immigrated to the United States when she was still a child. Twenty years ago, when Vera Pesotchinsky "s) was 14, she had difficulty speaking (her speech became fuzzy, slurred), which is why her parents turned to a speech therapist for help. Later, the girl began to have problems with coordination, sometimes she even fell, besides, Vera could not clearly make certain coordinated movements (for example, she could not peel potatoes). Vera's mother turned to specialists in neurology and psychiatry for advice. And only after 12 years and after misdiagnosis, the girl was finally diagnosed with LOTS.

Despite her disability, Vera graduated from Wellesley College. (Wellesley College) and received her Master of Management (MBA) from Santa Clara University (Santa Clara University). According to J. Gent, Vera lives independently, works daily in the family business, and in addition, she firmly believes that she did not become a victim of BTS, and her example indicates that one can live quite normally with this disease. Faith is an example for all patients with BTS, she speaks to all people affected by this disease and adds motivation to fight for health: “Of course, you can “fall apart” and be sick, but you can also be treated. Do whatever you can to treat the disease, because if I didn't, my situation would be much worse."

Pathophysiology

Tay-Sachs disease occurs due to insufficient activity of the enzyme hexosaminidase A, which catalyses the biodegradation of a specific class of fatty acids known as gangliosides. Hexosaminidase A is a vital hydrolytic enzyme that is found in lysosomes and degrades lipids. When hexosaminidase A stops functioning properly, lipids accumulate in the brain and interfere with normal biological processes. Gangliosides are produced and biodegraded rapidly, early in life, while the brain is developing. Patients and carriers of Tay-Sachs disease can be identified by taking a relatively simple biochemical blood test that detects hexosaminidase A activity.

Three proteins are required for the hydrolysis of GM2 ganglioside. Two of these are hexosaminidase A subunits and the third is a small glycolipid transport protein, the GM2 activator protein (GM2A), which acts as a substrate for a specific enzyme cofactor. Deficiency of any of these proteins leads to the accumulation of ganglioside, mainly in the lysosomes of nerve cells. Tay-Sachs disease (together with GM2 gangliosidosis and Sandhoff disease) occurs through genetic mutations inherited from both parents that disable or inhibit the breakdown of these substances. Most BTS mutations, according to scientists, do not affect functional elements squirrel. Instead, they cause improper accumulation or storage of the enzyme, making intracellular transport impossible.

BPS is an autosomal recessive genetic disorder. This means that if both parents are carriers of the defective gene, then the risk that a newborn child will be sick is 25%. Autosomal genes are chromosomal genes, they are not found on one of the sexes. Each person carries two copies of each autosomal gene, one inherited from each parent. If both parents are carriers of the mutation, then according to the probability of transmitting the disease to the child is 25%. Like all genetic diseases, CTS can occur in any generation, no matter when the mutation first occurred. Although the mutations that cause BTS are quite rare.

Autosomal recessive diseases occur when a child inherits two copies of a defective autosomal gene, that is, when one copy cannot participate in the transcription or expression process as a functional product for the formation of an enzyme.

BPS is caused by a mutation of the HEXA gene, which is located on chromosome 15 and encodes the activity of the alpha subunit of the lysosomal enzyme beta-N-acetylhexoaminidase A. By 2000, more than 100 mutations in the HEXA gene were identified, however, even today the number of known mutations is constantly increasing. These mutations occur as base pair insertions, deletions, splice site mutations, etc. Each of these mutations alters the protein product and thereby suppresses the activity of the enzyme. Recent demographic studies have shown which mutations arise and spread within small ethnic groups. The following groups formed the basis for the study:

. Ashkenazi Jews. They are characterized by the insertion of four base pairs in exon 11 (1278insTATC). This results in damage to the reading frame for the HEXA gene. This mutation is most common among Ashkenazi Jews and results in the infantile form of Tay-Sachs disease.
. Cajun . This ethnic group (whose population lives today in South Louisiana, USA) was separated from the rest of the population for several centuries through linguistic differences. BTS causes the same mutations that are most common among Ashkenazi Jews. The researchers looked at the ancestry of all carriers from several Louisiana families and identified the couple who had their first child with BTS. However, these spouses were not descendants of Jews living in France in the 18th century.
. French Canadians . This population is characterized by a long-sequence deletion that causes the same pathologies that cause the above mutations (found in Ashkenazi and Cajun Jews). Like the number of Ashkenazi Jews, the number of French-Canadians increased rapidly, from a small group of founders, however, they remained isolated from the rest of the population through geographical, cultural and linguistic barriers. The mutations in the two populations were previously thought to be identical, and the prevalence of BTS in eastern Quebec was due to gene flow. Some scientists then argued that a "sexually active Jewish ancestor" led to a disease-causing mutation among the French-Canadian population. This theory in narrow circles (among genetic scientists) became known as the "Hypothesis of the Jewish Fur Trader". However, subsequent studies have shown that the two mutations have nothing in common.

In the 1960s and early 1970s, when the biochemical basis of Tay-Sachs disease first became known, the mutation sequence that caused any genetic disease could not be pinpointed. Researchers of that era did not yet know how common polymorphism could be. The knowledge of that time reflects precisely "The Jewish Fur Trader Hypothesis" because according to it, only one mutation can spread between populations. Further research showed that BTS can cause a large number of mutations, each of which causes the appearance various forms diseases. It was BPS that became the first genetic disorder that showed the possibility of such a phenomenon as compound (combined). Such thorough knowledge became available due to the fact that BPS was the first disease for which genetic screening began to be widely used.

The very phenomenon of compound heterozygosity explains various forms of the disorder, including the emergence of the adult form of BPS. Potentially, the disease could result from inheriting two distinct mutated copies of the HEXA gene, one from each parent. The classic infantile form of BPS occurs when a child has inherited identically mutated copies of a gene from both parents, the dysfunction of which causes complete inactivation of the process of cleavage (biodegradation) of gangliosides. The adult form of BPS arises through the inheritance of various mutations, and although a person may be heterozygous, he can inherit two different HEXA gene mutations, the combined action of which leads to inactivation, change or decrease in the activity of the desired enzyme. If at least one copy of the HEXA gene allows hexosaminidase to perform its functions in a patient, then the result is the emergence of an adult form of BPS.

In heterozygous carriers, i.e. in individuals who have inherited only one mutant, the level of enzyme activity is also somewhat reduced, but they do not show any signs or symptoms of the disease. Bruce Korf explains why carriers of recessive mutations usually do not develop symptoms of a genetic disease:

“The biochemical basis for the dominance of wild-type over mutant alleles in congenital metabolic diseases can be understood by studying how proteins function. Enzymes are proteins that catalyze chemical reactions, i.e. only a small amount of substance is needed for the normal implementation of the catalysis reaction. If in homozygous individuals, the gene encoding the activity of the enzyme is mutated, then this leads to a decrease in the activity of the enzyme or to its absence in the body altogether, i.e. this person will exhibit an abnormal phenotype. But in heterozygous individuals, the level of enzyme activity is at least 50% of the normal level, through the expression (action) of the "wild type" alleles. This is usually sufficient to prevent violation ».

Diagnostics

Improvement of the developed testing methods allowed neuropathologists to diagnose Tay-Sachs disease and others much more accurately. neurological diseases. However, sometimes Tay-Sachs disease is misdiagnosed because doctors are not sure if it is a type of genetic disease that is common among Ashkenazi Jews.

Patients with this disease have a "cherry" spot of the macula, which is easy for the doctor to identify with an ophthalmoscope on the retina. This patch is an area of the retina that is enlarged by the accumulation of gangliosides in the surrounding retinal ganglion cells (these are the neurons of the central nervous system). Thus, only the cherry-red spot of the macula is the part of the retina that provides normal vision. Microscopic analysis of neurons shows that these cells are stretched (loaded with gangliosides) due to excessive accumulation of gangliosides. Without the use of molecular diagnostic methods, only the cherry spot of the macula is a characteristic feature and a sign in the diagnosis of all gangliosidoses.

Unlike some other lysosomal storage diseases (eg, Gaucher disease, Sandhoff disease), hepatosplenomegaly is not hallmark Tay-Sachs disease.

Journalist Amanda Pazornik (Pazornik) describes the experience of the Arbogast family: "Peyton was beautiful girl- but she couldn't sit, roll over, play with her toys. Moreover, Peyton's symptoms progressively worsened. Loud, incomprehensible noise frightened her. The inability to coordinate the movements of the muscles of the mouth and tongue led to the fact that she could choke while eating and was the cause of excessive salivation. Since neither of Peyton's parents was Jewish, her doctors did not suspect that she was afflicted with Tay-Sachs disease until she was 10 months old, when an ophthalmologist noticed the cherry-colored macular spot in her eyes. Peyton died in 2006 at the age of 3.5 years. This is a typical course of the disease. The child becomes progressively "lazy" due to impaired neurodegenerative development and shows an excessive hyperacusis reflex. The sick person becomes increasingly lethargic and has trouble eating. Spasticity and movement disorders may become noticeable. This disorder is most common among Ashkenazi Jews.

Prevention

BTS screening is carried out in two possible ways:

- Carrier detection test. During its implementation, it is revealed whether a healthy person is a carrier of one copy of the mutation. Many people who want to be tested for carrier identification are at-risk couples who are planning to start a family. Some people and couples want to be screened because they know an ancestor or family member has a genetic disorder.

Image from lori.ru

Tay-Sachs disease, or infantile gangliosidosis, along with Gaucher disease, belongs to hereditary disorders in the lipid metabolism system.

The basis of Tay-Sachs disease is a genetically determined disorder in the metabolism of special lipids - gangliosides. It is accompanied by their increased deposition in the gray matter of the brain, exceeding the norm by 300 times. In addition, gangliosides accumulate in the liver and spleen. The basis of the disease is a deficiency of one of the forms of enzymes that control lipid metabolism (hexosaminidase A). Rare: 1 in 250,000. It is inherited in an autosomal recessive manner. The gene defect is localized on the fifteenth chromosome.

Symptoms of Tay-Sachs disease

Found in children early age, although at birth the first 4 months, children are no different from their peers. Gangliosidosis develops slowly, the child gradually shows less activity, loses previously acquired skills, ceases to be interested in toys and recognizes the mother, the character of the child's crying changes, becoming drawn out and weak. Disorders appear first visual analyzer, the child does not fix his gaze and does not follow the object. Blindness develops quite quickly, often in parallel with deafness. Mental disorders also begin to progress, the degradation of intelligence is quickly noted, up to idiocy. Muscle hypotension is formed, the child stops holding his head, paralysis in the limbs, convulsions with the manifestation of opisthotonus, which are provoked by minimal external stimuli - light, sound. In parallel, pseudobulbar paralysis is formed: the act of swallowing is upset, violent crying or laughter occurs. Children quickly lose weight, after a year and a half there is a fatal outcome.

Diagnosis of Tay-Sachs disease

The diagnosis is based on an indication of similar cases in the genus, clinical manifestations, and the results of biochemical studies - they determine the activity of the enzyme in blood leukocytes and tissues. In addition, changes in the fundus of the eye, typical of Tay-Sachs disease, are noted - atrophy of the optic nerve papilla and a cherry spot in the macular region.

There is no specific treatment for Tay-Sachs disease. Prescribe drugs to maintain the liver, a complex of vitamin therapy, anticonvulsants. Highest value given to prenatal diagnosis of the disease with early interruption pregnancy.

Rare and dangerous Tay-Sachs disease - when genes kill

Tay-Sachs disease has several names: infantile gangliosidosis or early infantile idiocy amavrotic.

This disease refers to hereditary diseases of the nervous system and is quite rare.

The disease got its name in honor of the two doctors who discovered it - Warren Tey (an ophthalmologist from Britain) and Bernard Sacks (a neurologist from America).

The development of the disease depending on age

There are three forms of the disease:

a childish form of amaurotic family idiocy, in which babies experience a sharp deterioration in physical and mental health 6 months after birth (blindness, deafness develops rapidly, the child loses the ability to swallow);

teenage form, in which there is also a violation of swallowing, severe speech disorders, instability in gait appears, paralysis occurs;

an adult form that develops between the ages of 25 and 30. To the symptoms listed above is added schizophrenia, which occurs in the form of psychosis.

Causes of the disease

The causes of the disease lie in disorders at the genetic level that occur in the metabolism of gangliosides. These special lipids, exceeding 300 times the norm, are concentrated in the gray matter of the brain.

Accumulation also occurs in the liver and spleen. The disease is based on a deficiency of one of the types of enzymes that affect lipid metabolism (hexosaminidase A).

The disease occurs in the ratio: 1 in 250,000. Basically, this disease affects the population of ethnic groups, for example, the French, whose place of residence is Canada.

Jews of Eastern Europe are also susceptible to the disease, in which the incidence is higher - 1 per 4,000 people.

This disease develops in the baby who got two genes with a defect, that is, the disease is inherited in an autosomal recessive manner. What does it mean?

A child inherits genes from the father and from the mother in the same amount. If one or both chromosomes from a pair are affected, then they speak of the occurrence of a genetic disease. In people with Tay-Sachs disease, both chromosomes in a pair are defective.

The driving force for the development of this disease is the gradual accumulation in the nervous system of gangliosides - substances that affect the normal functioning of the cells of the nervous system.

All sick children have a damaged gene responsible for the complete synthesis of hexosaminidase enzymes.

A child's body with a congenital disease cannot continuously process fatty substances, so they accumulate and then are deposited in the brain.

This leads to the fact that the activity of nerve cells is blocked and severe consequences occur for the whole organism. In the body of a healthy child, gangliosides are constantly synthesized and broken down.

Pathology is diagnosed in babies at the age of about six months, since up to four to five months the child develops quite normally, like all children of this age.

Friedreich's hereditary ataxia causes serious disorders of the nervous system - causes, symptoms and treatment of pathology.

At a later stage between the first year of life and the second year of life, the baby is more likely to experience seizures, manifested in the form of convulsions and paralysis.

Babies do not gain weight, but rapidly lose it. With this development of the disease, the child rarely survives to the age of five.

Signs of illness in adults

The adult form is very rare and occurs in patients in their 20s and 30s. It usually does not have a fatal outcome.

The disease manifests itself in gait disturbance and rapid deterioration of neurological functions. With such a disease, an adult can live after the diagnosis is established for 10-15 years.

Diagnosis of the disease

Before determining the diagnosis, the doctor examines the results of the studies, asks the parents in detail about the clinical manifestations, and finds out if there have been cases of this disease in the family.

There are also changes in the papilla of the optic nerve: it atrophies.

It can not be cured, it is necessary to support

Treatment of Tay-Sachs disease must begin before the onset of neurological signs. Use blood transfusion, plasma.

There are no drugs and specific methods that cure Tay-Sachs disease.

The latter are often ineffective against seizures that occur with this disease. Medical care consists in simply alleviating the symptoms of the manifestation of the disease, but if we are talking about a late form, then to delay the development of the disease.

The prognosis for this disease is unfavorable.

Disease prevention

To prevent the disease, spouses who want to have children must be tested for the presence of the gene for this disease if at least one of the spouses had cases of Tay-Sachs disease in the family.

If such a gene is found in both spouses, then they are categorically not recommended to conceive children. It happens that during the examination the woman is already carrying a child, then a special procedure is prescribed to identify the defective gene in the child - amniocentesis.

For this, amniotic fluid obtained by taking a puncture of the amniotic membrane is subjected to laboratory testing. If the defective gene is found, the pregnancy must be terminated.

If the future parents have accurate information that they are carriers of the defective gene, and pregnancy has already occurred, then it is necessary to undergo a screening test at the twelfth week.

To conduct research, doctors take blood from the placenta to find out if the future baby has inherited mutant genes.

Future parents need to be responsible for their own health and the health of their future children and follow all the recommendations of doctors.

Prenatal diagnosis during each pregnancy enables a married couple to give birth to healthy children.

Tay-Sachs disease is an extremely rare hereditary disease that has autosomal recessive inheritance and is characterized by CNS damage.

This disease, which belongs to the group of lysosomal storage diseases, is also known as early infantile amaurotic idiocy or GM2 gangliosidosis. The probability of having a child with this disease reaches 25% if the mother and father have a mutant gene.

Tay? Sachs disease is widespread among Ashkenazi Jews. They have approximately 3% of the population with the mutant HEXA gene. In addition, the disease is relatively common in Cajuns and French Canadians. As for other population groups, the average frequency of carrying such a gene is only 0.3%.

Etiology and pathogenesis

Mutation of the HEXA gene, which is responsible for the synthesis of the enzyme hexose aminidase A (a mediator catalyst involved in the utilization of gangliosides in the CNS), leads to a genetic defect. If the enzyme is absent, gangliosides begin to accumulate in the neurons of the brain. As a result, the functioning of neurons is disrupted, which further leads to their complete destruction.

Tay's disease? Sachs (amaurotic idiocy) comes in three forms:

children's - manifests itself at the age of six months and is accompanied by a progressive decrease in mental and physical capabilities;

teenage - there are motor-cognitive disorders, dysarthria, dysphagia, ataxia, spasticity;

adult - is a rare form, manifests itself at 25–30 years of age and is accompanied by a progressive decline in neurological functions.

In the first form of the disease, death occurs at 3-4 years. In the adolescent form of the disease, death is guaranteed at 15–16 years of age.

Symptoms of Tay? Sachs disease are associated with CNS damage. Newborns with this hereditary disease develop normally for the first six months. At the age of six months, there is a regression in the physical and mental formation. The child loses hearing, the ability to swallow. A gaze appears, which is directed to one point. The child becomes lethargic and also only responds to loud sounds. He subsequently goes blind and loses his hearing. There are disturbances in mental development, the head becomes large sizes. Convulsions are observed, muscles atrophy, paralysis occurs. Death occurs before the age of four.

With adolescence and adult form disease symptoms are milder. In this case, there is a violation of speech, there are muscle spasms, gait, fine motor skills and coordination are disturbed, vision is reduced, intelligence and hearing are deteriorating.

Tay's disease? Sachs disease is determined by the presence of a red spot, which is located on the retina opposite the pupil. It can be seen during examination by an ophthalmologist. A red spot on the retina indicates that gangliosides have accumulated in this place in the ganglion cells. After examination with an ophthalmoscope, the doctor prescribes the following:

detailed blood test;

microscopic analysis of neurons;

screening.

To date, treatment for the genetic disease of Tay-Sachs has not been developed. Medical care is aimed at relieving symptoms and delaying the development of the disease, at least for a while.

Throughout life, patients are provided with palliative care, which includes tube feeding, skin care, and more. With seizures, anticonvulsants usually do not help.

Tay's disease? Sachs is incurable. With the best outcome, patients with the childhood form of the disease live up to five years.

Prevention of the disease consists in conducting a survey of married couples for the presence of a mutant gene. If it is found in both spouses, they are advised not to have children. When a woman who is already pregnant is diagnosed, an amniocentesis is prescribed to detect defective genes in the fetus.

Tay-Sachs disease. Rare hereditary disease

Tay-Sachs disease is a disease that is inherited, characterized by very rapid development, damage to the central nervous system and brain of the child.

The disease was first described by the English ophthalmologist Warren Tey and the American neurologist Bernard Sachs in the 19th century. These outstanding scientists have made an invaluable contribution to the study of this disease. Tay-Sachs disease is enough rare disease. Certain ethnic groups are predisposed to it. Often this disease affects the population of the French of Quebec and Louisiana in Canada, as well as Jews living in Eastern Europe. In general, the incidence of the disease in the world is 1:250,000.

Tay-Sachs disease occurs in a person who inherits mutant genes from both parents. In the case when only one of the parents is the carrier of the gene, the child may not get sick. But, in turn, it becomes a carrier of the disease in 50% of cases.

If a person has an altered gene, his body stops the production of a certain enzyme - hexosaminidase A, which is responsible for the breakdown of complex natural lipids in cells (gangliosides). It is not possible to remove these substances from the body. Their accumulation leads to blocking of the brain and damage to nerve cells. This is what causes Tay-Sachs disease. Photos of the sick can be seen in this article.

Like other hereditary diseases of newborns, this disease can be diagnosed at an early stage. If parents have a suspicion that their baby is suffering from Tay-Sachs syndrome, then you need to urgently contact an ophthalmologist. After all, the first sign of this terrible disease is a cherry-red spot, which is observed when examining the fundus of a child. The spot occurs due to the accumulation of gangliosides in the cells of the retina.

Then, studies such as a screening test (extensive blood test) and microscopic analysis of neurons are carried out. A screening test shows if the protein hexosaminidase type A is being produced. An analysis of neurons reveals if they have gangliosides.

If parents know in advance that they are carriers of a dangerous gene, then it is also necessary to undergo a screening test, which is performed at 12 weeks of pregnancy. During the study, blood is taken from the placenta. As a result of the test, it will become clear whether the child has inherited mutant genes from his parents. This test is also performed in adolescents and adults when similar symptoms diseases and poor heredity.

Development of the disease

A newborn suffering from Tay-Sachs syndrome outwardly looks like all children and seems to be quite healthy. It is a common thing when such rare diseases do not appear immediately, but in the case of the disease in question, only by six months. Up to 6 months, the child behaves in the same way as his peers. That is, he holds his head well, holds objects in his hands, makes some sounds, perhaps begins to crawl.

Since the gangliosides in the cells are not broken down, a sufficient amount of them accumulates so that the baby loses the acquired skills. The child does not react to the people around him, his gaze is directed to one point, apathy appears. After a certain period of time, blindness develops. Later, the child's face becomes like a puppet. Usually, children with rare diseases that are associated with mental retardation do not live long. In the case of Tay-Sachs disease, the baby becomes disabled and rarely lives to be 5 years old.

Symptoms of the disease in infants:

At 3-6 months, the child begins to lose contact with the outside world. This is manifested in the fact that he does not recognize close people, is able to respond only to loud sounds, cannot focus his vision on an object, his eyes twitch, and later his vision worsens.
At 10 months, the activity of the baby decreases. It becomes difficult for him to move (sitting, crawling, turning over). Vision and hearing are dulled, apathy develops. Head size may increase (macrocephaly).
After 12 months, the disease is gaining momentum. Becomes noticeable mental retardation child, he very quickly begins to lose hearing, vision, muscle activity deteriorates, breathing difficulties arise, seizures appear.
At 18 months, the child completely loses hearing and vision, convulsions, spastic movements, generalized paralysis appear. The pupils do not react to light and are dilated. Further, decerebrate rigidity develops due to brain damage.
After 24 months, the baby suffers from bronchopneumonia and most often dies before reaching 5 years of age. If the child was able to live longer, he develops a disorder in the coordination in the contractions of different muscle groups (ataxia) and a slowdown in motor skills, which progresses between 2 and 8 years.

Tay-Sachs disease is also represented by other forms.

Juvenile hexosaminidase A deficiency

This form of the disease begins to appear in children between the ages of 2 and 5 years. The disease develops much more slowly than in infants. Therefore, the symptoms of this hereditary disease are not immediately visible. There are mood swings, clumsiness in movements. All this does not particularly attract the attention of adults.

muscle weakness appears;

small cramps;

slurred speech and impaired thought processes.

Illness at this age also leads to disability. The child lives up to 15-16 years.

Youthful amorotic idiocy

The disease begins to progress at 6-14 years of age. It has a weak course, but as a result, the sick person acquires blindness, dementia, muscle weakness, possibly paralysis of the limbs. Having lived with this disease even for several years, children die in a state of insanity.

Chronic form of hexosaminidase deficiency

It usually appears in people who have lived for 30 years. The disease in this form has a slow course and, as a rule, proceeds easily. There are mood swings, slurred speech, clumsiness, decreased intelligence, mental abnormalities, muscle weakness, seizures. Tay-Sachs syndrome in chronic form was opened relatively recently, so it is not possible to make forecasts for the future. But it is clear that the disease will definitely lead to disability.

Treatment of Tay-Sachs disease

This disease, like all degrees of idiocy, does not yet have a cure. Patients are prescribed supportive care and meticulous care. Usually, drugs prescribed for seizures do not work. Since babies do not have a swallowing reflex and often have to feed them through a tube. The immunity of a sick child is very weak, so it is necessary to treat concomitant diseases. Usually children die due to some kind of viral infection.

Prevention of this disease is the examination of the couple, aimed at identifying mutations in the genes that characterize Tay-Sachs disease. If there are any, then a recommendation should not be made to try to have children.

If your child is sick

At home care you need to learn how to do postural drainage and nasogastric aspiration. You will have to feed the child through a tube, and also make sure that there are no bedsores on the skin.

If you have other healthy children, then you need to examine them for the presence of the mutant gene.

Treatment and prevention

Unfortunately, Tay Sachs disease is an incurable disease, but symptomatic therapy is prescribed to alleviate its course, which will make the life of a sick child more comfortable. Depending on the prevailing clinical picture appropriate medications may be prescribed.

As a rule, help is required not only for the child himself, but also for his parents, because the news of such a serious illness is almost always shocking. In this case, parents are advised to find a support group where they can communicate with people facing a similar problem and receive the necessary psychological support. It is also advisable to consult a geneticist so that each family member can understand and accept the current situation.

Since the disease will gradually progress, the child will need special care. If necessary, you should consult a doctor about obtaining additional help, it is also important to pay a lot of attention to the child, let him know that his parents love and support him. The life expectancy of such patients can vary over a fairly wide range. With mild symptoms and proper care, some people with amaurotic idiocy live almost as long as healthy people.

As for the prevention of Tay Sachs disease, it consists, first of all, in the competent planning of pregnancy. A married couple who decide to have offspring should be examined by a geneticist to find out if one of the future parents is a carrier of the defective gene. If such a gene was found during the study, the decision whether to have a child or not remains only with the parents.

Description

When an enzyme, such as hexosaminidase A, which is needed to break down certain substances such as fats, is missing or ineffective, they accumulate in lysosomal. This is called abnormal "storage" when there is too much fatty material in the lysosome.

Symptoms associated with Tay Sachs syndrome include:

exaggerated startle reaction to sudden noises;
lethargy;
loss of previously acquired skills (psychomotor regression);
greatly reduced muscle tone(hypotension).

As the disease progresses, children develop;

cherry-red spots in the middle layer of the eyes;
there is a gradual loss of vision and hearing;
increased muscle stiffness;
movement restriction progresses (spasticity);
possible paralysis;
uncontrolled electrical disorders of the brain (convulsions);
deterioration of cognitive processes (dementia).

The classic form of Tay-Sachs disease occurs in infancy. This is the most common form, and is fatal in early childhood.

There are also adolescent and adult forms of the syndrome, but they are rare. Children with the juvenile form, called subacute, develop symptoms later than those with the infantile form and usually live longer.

The adult form, called late onset, occurs between adolescence and mid-30s. Symptoms and severity vary.

Tay Sachs syndrome is inherited in an autosomal recessive manner. The disorder results from changes (mutations) in a gene known as HEXA, which regulates the production of the enzyme hexosaminidase A. The HEXA gene is displayed on the long arm (q) of chromosome 15 (15q23-q24). There is no cure, it is aimed at relieving specific symptoms.

Another name for the disease is GM2 type 1 gangliosidosis. There are two other related diseases called Sandhoff's disease and hexosaminidase activator deficiency, which are indistinguishable from Tay-Sachs syndrome. They can only be differentiated by testing, determining the underlying cause. These two disorders also cause a decrease in hexosaminidase activity, but are caused by changes in different genes. These three disorders are known as GM2 gangliosidoses.

Synonyms

GM2 gangliosidosis;
GM2 gangliosidosis type 1;
Hexoamidase alpha subunit deficiency (option B);
Hexosaminidase A deficiency;
Lack of HEXA;
Sphingolipidosis, Thai-Sachs;

Infantile Tay-Sachs disease;
subacute disease;
late stage.

Affected populations

The disease affects men and women in equal numbers. It is more common among the Jewish people of Ashkenazi origin, that is, among Eastern or Central European origin. Approximately one in 30 Ashkenazi Jews carries the altered gene. In addition, one in 300 people of non-Ashkenazi Jewish heritage is a bearer.

People of Italian, Irish, French, Canadian ancestry have been reported, especially those living in the Cajun community of Louisiana and southeastern Quebec. In the general population, the transfer rate for an altered gene is approximately 1 in 250-300 people.

Late disease occurs less frequently than the infantile form. but rare forms disorders often go unrecognized. They are underrepresented, making it difficult to determine the true incidence of disorders in the general population.

Diagnostics

The diagnosis is confirmed by a thorough clinical evaluation and specialized tests such as blood tests that measure hexosaminidase A levels in the body. Hexosaminidase A is reduced in people with Tay-Sachs disease, absent in the infantile form.

Molecular genetic testing confirms the diagnosis. It detects mutations in the HEXA gene that cause the disorder.

In some cases, it is possible that the diagnosis of Tay-Sachs syndrome may be suspected before birth (prenatally) based on specialized tests such as amniocentesis, chorionic villus sampling (CVS). During an amniocentesis, a sample of the fluid surrounding the developing fetus, CVS obtains a tissue sample from part of the placenta. These samples are studied to determine if hexosaminidase A is present, in a manner that is absent or very low in people with the disease. This is called enzyme analysis.

Blood tests can determine if people are carriers of Tay-Sachs disease (there is one copy of the gene). Relatives must be tested to determine if they are carriers of the disease gene. Couples who are planning to have a baby and are of Jewish ancestry (not just Ashkenazi) are encouraged to get screened before they become pregnant.

There is no specific treatment. It targets specific symptoms and may require a coordinated effort by a team of specialists. Genetic counseling is recommended for affected individuals and their families. Psychosocial support is essential for the whole family.

Due to potential feeding difficulties, nutritional status and proper hydration should be monitored. Nutritional support may be required. In addition, a feeding tube is sometimes needed to help prevent food, liquid, or other foreign material from accidentally entering the lungs (aspiration).

Anticonvulsants are used to treat seizures but may not be effective for everyone. In addition, the type and frequency of seizures often require a change in the type of medication or dosage.

Exploratory Therapy

Work continues on the development of an enzyme replacement therapy(ERT) for Tay-Sachs disease. It consists in replacing the enzyme in individuals who experience a lack or absence of it.

Synthetic versions of the missing enzymes are being used to treat people with other lysosomal storage disorders, including Hurler's syndrome, Fabry syndrome, and Gaucher's disease. However, ERT has not been successful for people with Tay Sachs syndrome. One of the problems is the inability to cross the blood-brain barrier.

Gene therapy is being explored as a possible approach to the treatment of some lysosomal memory disorders. In gene therapy, a defective gene is replaced with a normal one, allowing the production of an active enzyme that prevents the development and progression of the disease.

Given the constant transmission of the normal gene that produces the active enzyme in all disease foci, this form of therapy is likely to lead to a "cure". However, there are currently technical difficulties for the success of this approach.

Chaperone therapy is also being studied. This type of therapy uses very small molecules that attach to newly created hexosaminidase A enzymes before the mutated ones are destroyed. They direct them to the lysosome, where the enzymes perform their normal function.

Such a molecule can cross the blood-brain barrier. The therapy is in the early stages of research.

A drug called pyrimethamine has been used as a treatment for Tay-Sachs disease. Affected individuals taking this drug have shown increased hexosaminidase A activity.

However, it did not lead to a marked improvement in neurological or psychiatric symptoms. Required additional research to determine if pyrimethamine plays any role in the treatment of this syndrome.

Neurogenetics and hereditary diseases

What do they depend on? From the quality of genetic information inherited from parents and from the conditions of the environment in which a person is located throughout life. Knowing the features of the genome can not only diagnose rare diseases, incl. and nervous system, but also with a high degree of probability to determine the characteristics of metabolism and the risks of future diseases, which is important for the correct selection medicines, choice of profession, rational nutrition, etc.

Neurogenetics studies the role of heredity in the occurrence of diseases of the nervous system. Especially great success molecular genetics have been achieved in the study of progressive degenerations of the brain, neuromuscular diseases and epileptic syndromes.

Practice of a geneticist in Samara

In the clinical practice of a neurologist, to determine the cause of neurological disorders, it is important to use the possibilities of such laboratory method, as the detection of mutations and polymorphisms in the genes responsible for the functioning of the nervous system, muscles, for the metabolism in the smallest cell structures, such as the nucleus, mitochondria, lysosomes and pyroxisomes. Dozens of enzymes “work” in these subcellular organelles, on which the energy supply of cells depends. Each enzyme is controlled by a specific gene. The presence of a defect in the gene leads to blockage of the chain chemical reaction with the accumulation of substances that have not passed the full cycle of chemical transformations. Accumulation diseases occur. One of them is Fabry disease, in which strokes are frequent even in young people. Drugs that replace a "poorly functioning" enzyme when taken for life (as in the treatment of diabetes) allow a person to be healthy.

In addition, a number neurological disorders occurs with chromosomal pathology, which can be revealed by the study of chromosomes in human blood cells. This study is called karyotyping.

Biochemical methods for identifying the genetic characteristics of bioenergetics and metabolic defects specific to the so-called orphan diseases with neurological manifestations are also of interest to a neurologist. Subtle knowledge of the causes and pathogenesis of neurological symptoms allows the doctor to make important recommendations for therapy.

By the way, molecular diagnostics and karyotyping are carried out once in a lifetime, since the genotype and set of chromosomes do not change. These analyzes of yours are important even for first-degree relatives, since defects in genes and chromosomes can be inherited.

The effectiveness of neurogenetics on the example of epilepsy

The breadth of the diagnostic and therapeutic possibilities of neurogenetics is well demonstrated by the example of epilepsy. This disease has been known since ancient times and proceeds in the form of convulsive seizures, both partial and generalized tonic-clonic, myoclonic. The linkage of certain forms of epilepsy with mutations of specific genes, point mutations of mitochondrial DNA, and chromosomal disorders has been proven.

There are several reasons for the occurrence of a convulsive syndrome associated with genetics. These are chromosomal diseases: extra 4th or 21st chromosomes, ring 14th chromosome give generalized clonic-tonic, myoclonic convulsions. Ring chromosome 20 results in complex partial and secondary generalized seizures. With a fragile X chromosome, simple partial, atypical absences, generalized convulsions are observed. A deletion (separation of a part) of the 4th or long arm of the 15th chromosome is also manifested by a convulsive syndrome.

These are also hereditary metabolic diseases that occur with convulsive syndrome: phenylketonuria, aciduria, Menkes disease and Wilson-Konovalov disease, non-ketonemic hyperglycinemia, gangliosidosis, adrenoleukodystrophy, galactosialidosis, Krabbe, Tay-Sachs, Sandhoff, Lafora, Gaucher diseases. MELAS syndrome - mitochondrial myeloencephalopathy, lactic acidosis, stroke-like episodes. Syndrome MERRF - myoclonus epilepsy with "torn" red fibers and muscles, detected by histological examination.

More than 500 different forms of progressive muscular dystrophies and neuromuscular syndromes are known to neurogenetics, so the consultation of such a specialist can be very useful for the patient and his family.

In the rehabilitation of patients after acute vascular pathology of the nervous system (stroke), drugs called anticoagulants are used. They prevent the formation of blood clots in blood vessels. But every 6th European is not sensitive to aspirin and taking this drug will not give the expected effect from it. Another drug that works similar to aspirin is called Warfarin. It was noticed that in one part of the people it causes a good anticoagulant effect, in the other it does not have the expected effect, in the third it causes tissue bleeding. It turned out that different molecular defects in the gene responsible for the metabolism of this drug in the human body lead to such a different result. Thus, molecular diagnostics of an individual tendency to thrombosis and testing of the genes responsible for the exchange of anticoagulants make it possible to choose an INDIVIDUAL effective therapeutic dose of the drug.

Consultation of a geneticist in Samara

Neurogenetics allows you to most accurately determine the prognosis for the patient's life and health, as well as the likelihood of children inheriting the patient's hereditary disorders of the nervous system. It is even possible to determine the presence of a hereditary disease in an unborn child in the prenatal period.

We have a geneticist in our clinic.

Tay-Sachs disease - what is it?

Early childhood amaurotic idiocy is a rare disease that is inherited. It affects the brain and nerve cells. There are two forms of this disease:

The first (the most common) begins to develop almost immediately after the birth of the child, and the life expectancy of the baby in this case is 4-5 years.

Late-onset Tay-Sachs disease appears between puberty and age 23-26 years. The life expectancy of the patient depends primarily on the severity of the symptoms of the disease. Such patients can live the same period of time as a healthy person.

What can cause this disease?

Tay-Sachs disease can develop if the parents passed on to the child the affected (mutated) gene.

Genes

They are part of the cells of the body and contain genetic information or deoxyribonucleic acid (DNA), which is responsible for physical characteristics person. Genes (individually or in combination) determine what genetic traits a child will inherit from parents, such as blood type, hair color, eye color, and the likelihood of developing a particular disease. A certain number of genes make up a chromosome. Damage to both the gene and the chromosome causes changes in the processes and functions of the body. These defects may practically not appear, but sometimes they cause the development of such serious illnesses like hemophilia or Down syndrome. Health problems such as Still's disease (a form of rheumatoid arthritis in children) or depression can also be the result of abnormalities at the genetic level. The mutated gene is passed from parents to children. Hereditary diseases are usually genetic in nature. A person may be born with a genetic background that will influence an increased susceptibility or risk of a particular disease.

When a baby inherits the mutated gene from both parents, it becomes sick.

If there is a transmission of the affected gene from one of the parents, the child becomes defect carrier. This means that he will have given gene in the body, but he himself will not get sick.

Disease carrier

This is a person who can pass on to his children a hereditary (genetic) disease, although he himself is not affected by the disease. In addition, there is also a risk of transmission of carrier status. Some diseases are caused precisely by deviations at the gene and chromosomal levels. Each person inherits 23 chromosomes from each parent. Thus, he gets 23 pairs of chromosomes in the body. If one or both chromosomes of a pair are affected, a genetic disease occurs. In most cases, in a person with the above defect, both chromosomes in a pair are damaged. This disorder is called an autosomal recessive disorder. Certain genetic diseases arise due to damage to the X and Y chromosomes, which are responsible for determining sex. If at least one chromosome from a pair is abnormal, the person may be a carrier of the disease.

The mutated gene prevents the body from producing such enzyme as hexosaminidase A, which is responsible for the breakdown of gangliosides (complex natural lipids) in cells. In the case of their accumulation, blocking of the brain and damage to nerve cells occurs, which causes Tay-Sachs disease.

In late-onset Tay-Sachs disease, the body produces a reduced amount of the above enzyme. Individuals with this disease will inherit the late developmental hexosaminidase A gene from both parents, or one of the late and incapacitated genes. The risk of the appearance of a mutated gene increases in people with roots who go to Ashkenazi Jews, since 1 out of 30 representatives of this nationality is a carrier of this disease. In addition, people of French Canadian origin living in the eastern part of the St. Lawrence River Valley of Quebec and Cajuns (French-speaking residents of Louisiana) are also predisposed to the development of Tay-Sachs disease.

Tay-Sachs disease - symptoms

After birth, a child with such a defect looks absolutely healthy. However, you may notice the following:

At 3-6 months, the baby begins to weakly visually react to the actions around him, and it is difficult for him to focus on the subject. The doctor can detect red dots on the child's retina.

At 6-10 months, the child has a decline in activity. It becomes difficult for him to sit and roll over. In addition, there are problems with hearing and vision.

After 10 months, the disease is actively progressing. The child may seizures, loss of vision and muscle atrophy.

Attack

These are sudden bursts of abnormal electrical activity of the brain that affect the functioning of the muscular system, control of the motor apparatus, distort speech, visual images and psychological perception of reality. The degree of damage is individual for each. It also depends on the type, frequency and severity of seizures. In some cases, a person falls to the floor and begins to convulse, in which the muscles of the body are strongly contracted, and involuntary twitching of the limbs occurs. Others enter a trance state with only a few muscles remaining mobile. Sometimes they smell or see images that are uncharacteristic healthy person. Often a seizure is a symptom of other health problems, such as high temperature body (especially in children), impaired cerebral circulation infection, low blood glucose (hypoglycemia), low blood pressure, or a brain tumor.

As a baby develops late-onset Tay-Sachs disease, symptoms such as clumsiness and mood swings may not be taken seriously. To more late signs diseases include spasmodic twitching and muscle weakness, slurred speech, and problems with thought processes. The nature of complications depends on how much hexosaminidase A is produced in the body.

Tay-Sachs disease - disease recognition system

If the attending physician suspects that the child is affected by Tay-Sachs disease, he will first of all examine the patient and take a blood test to check the level of hexosaminidase A in the body. A genetic test is needed to confirm the diagnosis.

What is the treatment?

The main treatment for Tay-Sachs disease is to control symptoms and ensure that the child is comfortable in everyday life, since there is no panacea for this disease today. In this case, it will be useful to undergo genetic counseling and attend therapy sessions where you can find support and communicate with people who have a similar problem. If you develop late-onset Tay-Sachs disease, treatment is also based on monitoring symptoms. Depending on your symptoms, you may receive certain medications, such as for depression. Undoubtedly, the news that your child has been diagnosed with Tay-Sachs disease can shock you. In such a situation, in addition to taking care of the child, you should also remember about your health. You should talk to your doctor about the following topics:

Your experiences and help in caring for the baby.

Support group in your area.

Genetic counseling for the whole family so that everyone accepts the current situation.

As the disease progresses, the child may need more careful care. Cheer him up and inspire him to fight, give him your love and affection. You may need extra help caring for your baby. Talk to your doctor about where to go for this.

Tay-Sachs disease - why do you need to be screened for the presence of the disease?

Carriers of this defect can pass on the disease to children even if they themselves are not sick. If you and your partner are carriers of Tay-Sachs disease, your children have a 1 in 4 (25%) chance of developing the same defect. When you are considering having a baby, the American Corporation of Obstetricians and Gynecologists recommends that you do the following:

Both partners must be screened if they are Ashkenazi Jewish, Cajun (Louisiana French-speaking), French Canadian, or family history for this disease. In the event that the examination shows that you are positive, subsequent decisions will help make the passage genetic counseling.

If at least one of the partners meets the above categories, he must also pass the testing procedure. One positive result on the carrier of the disease also involves the examination of another partner.

Family history

From the family history, the doctor can find out if the patient has blood relatives with a similar disease. This will help the specialist determine the degree of risk of transmission of the defect by inheritance.

Blood relatives include both living and deceased family members. It can be:

Immediate relatives (parents, sisters, brothers or children).

Relatives in the second degree of kinship (uncles, aunts, nephews, nieces, grandfathers, grandmothers).

Relatives in the third degree of kinship (cousins).

In some cases, the family history can be quite complex. It depends on several factors:

How closely related is the patient to a family member who has been diagnosed with the disease?

How many relatives had similar health problems.

genetic counseling

Genetic counseling is an explanation medical worker(genetic consultant or geneticist), whose specialization is to help people understand the danger of transmission of genetic diseases, as well as explain the possibility of inheriting this type of disease in a child (sickle cell disease, cystic fibrosis, hemophilia).

Genetic counseling includes:

Explanation to parents (future) how a certain disease can be inherited and transmitted from them to the child.

Discuss the complications that a genetic disease can cause.

Discuss the possibility and procedure for testing for the presence of a genetic disease before a woman becomes pregnant or before the birth of a child.

Consideration, based on the results obtained, of the possibility of a couple having a child with a genetic disease.

Help in understanding the risk of developing a genetic disease such as Huntington's disease. Genetic counselors also help a person with treatment for a genetic disorder, if needed.

Helping both individual patients and couples make decisions in favor of testing for a genetic disease.