Tay-Sachs disease - a serious hereditary disease characterized by progressive motor impairment and mental retardation as a result of the defeat of the meninges of the child.During the first six months of life, the development of children with Tay-Sachs disease occurs absolutely normal, after which brain function is impaired, and in most cases, babies do not live up to five years.
the first time the disease has been described in detail in the late nineteenth century American neurologist Bernard Sachs and British ophthalmologist Warren Tay, who made an invaluable contribution to the study of this disease.The frequency of disease - one case per 250,000 population
Tay-Sachs disease - reasons
Tay-Sachs disease is a rare disease, and it mainly exposed to certain ethnic groups.Most often, the disease suffers from the French Canadian population of Quebec and Louisiana, as well as the Jews of Eastern Europe.Ashkenazi Jews have this pathology occurs in 1 in 4000 newborns.
Tay-Sachs disease is inherited in an autosomal recessive type.This suggests that only a child can get sick, who inherited two defective genes at once - the first from the mother and the other from the father.In the case of a defective gene from only one of the biological parents, the child is not sick, but with a 50% chance to become a carrier of the defective gene, thus putting at risk their future offspring.
What could happen if the defective gene have both parents:
- a 25% chance the child will not be a carrier of the gene and be born completely healthy
- 50% chance the child will be a carrier of the gene and be born completely healthy
- With a 25% chance the child will inherit two affected genes and will be born with Tay-Sachs disease
mechanism of this disease is to accumulate in the nervous system gangliosides - the substances responsible for the normal functioning of nerve cells.Gangliosides in a healthy body is constantly synthesized and therefore are constantly broken down, and the enzyme systems responsible for maintaining the delicate balance between synthesis and degradation.Sick kids have a damaged gene responsible for synthesis of the enzyme hexosaminidase type A in children with congenital deficiency of the enzyme is not able to consistently break down quickly formed and accumulated fatty substance - gangliosides are being postponed in the brain, blocking the work of nerve cells, which leads to very heavySymptoms
Tay-Sachs disease - symptoms
Typically, Tay-Sachs disease affects children aged about six months.At the beginning of the disease, a child lost contact with the outside world, it appears directed at one point closer look, it becomes apathetic and responds only to loud sound.After that, the child loses acquired skills (for example - ceases to creep), delayed mental development, and after a while blind.Muscle function (the ability to eat, drink, move, make sounds and so forth.) Are greatly reduced, sometimes to the point of total loss becomes disproportionately large head.In the later stages of the disease (usually between 1 and 2 year of life) can appear seizures.In most cases, a child dies before reaching the age of five
Separation symptoms by age:
- From 3 to 6 months: the child observed difficulty focusing on the subject, deteriorating vision, twitching eyes, there is unjustified play enoughloud sounds
- From 6 to 10 months: the baby is observed hypotonia (decreased muscle tone), it becomes less active, significantly deteriorating hearing and vision, the head significantly increases in size (macrocephaly), blunted motor skills, the child is difficult to roll over and sit
- After 10 months: becomes apparent mental retardation, blindness develops paralysis, there are difficulties in breathing, swallowing disorders, seizures
Clinical variants of Tay-Sachs:
- Chronic shortages hexosaminidase (type A).Symptoms of the disease can develop at the age of 3 to 5 years, and in their early thirties.Proceeds disease is relatively easy: patients may be slightly broken it (becomes inaudible) suffers fine motor skills, coordination and gait;may experience muscle spasms, mental disorders and intellectual impairment.The majority of patients deteriorated markedly hearing and vision.Due to the fact that this form of Tay-Sachs opened quite recently, the long-term forecast of future life of these patients is controversial.With high probability it can be argued that the disease is gradually leads to disability and subsequent death
- Juvenile hexosaminidase deficiency (type A).Symptoms of this disease developing in the age range of 2 to 5 years.Despite the fact that this form of the disease progresses much slower than its classical version, the child's death is still inevitable occurs around the age of 15 years
assumption that a child has the disease occurs,as a result of the inspection kid ophthalmologist (ophthalmoscopy), the fundus reveals a cherry-red spot.This area on the retina shows that it is at this point in the retinal ganglion cells there is an increased accumulation of ganglioside.After this observation, the doctor prescribes the following types of research: microscopic analysis of neurons, screening, detailed blood tests
Tay-Sachs disease - treatment
Unfortunately Tay-Sachs disease can not be cured.Even if the best care, almost all children with children's forms of the disease live a maximum of five years.For life to relieve symptoms present, patients receive palliative care (feeding through a tube to include nutritional supplements, careful skin care and so forth.).Anticonvulsants often powerless against seizures.
Prevention of the disease is mandatory testing for couples that they have the gene Tay-Sachs.If both spouses such a gene has been found, they are advised not to have children.If at the time of diagnosis gene a woman is already pregnant, to identify the defective gene in the fetus may amniocentesis.