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Tay-Sachs Disease

Tay-Sachs diseases causes a progressive deterioration of nerve cells and of mental and physical abilities that begins around six months of age. The disease occurs when harmful quantities of cell membrane components known as gangliosides accumulate in the brain's nerve cells.

PubMed Health Glossary
(Source: Wikipedia)

About Tay-Sachs Disease

Tay-Sachs disease (TSD) is a fatal genetic disorder, most commonly occurring in children, that results in progressive destruction of the nervous system. Tay-Sachs is caused by the absence of a vital enzyme called hexosaminidase-A (Hex-A).

Without Hex-A, a fatty substance, or lipid, called GM2 ganglioside accumulates abnormally in cells, especially in the nerve cells of the brain. This ongoing accumulation causes progressive damage to the cells.

In children, the destructive process begins in the fetus early in pregnancy. However, a baby with Tay-Sachs disease appears normal until about six months of age when its development slows. By about two years of age, most children experience recurrent seizures and diminishing mental function. The infant gradually regresses, and is eventually unable to crawl, turn over, sit or reach out.

Eventually, the child becomes blind, cognitively impaired, paralyzed and non-responsive. By the time a child with Tay-Sachs is three or four years old, the nervous system is so badly affected that death usually results by age five.

A much rarer form of Tay-Sachs, Late-Onset Tay-Sachs disease, affects adults and causes neurological and intellectual impairment. Only recently identified, the disease has not been extensively described. As for the childhood form of Tay-Sachs, there is no cure. Treatment involves managing the symptoms of the disease.

Defect in Hex-A Gene Causes Tay-Sachs:

Tay-Sachs disease results from defects in a gene on chromosome 15 that codes for production of the enzyme Hex-A. We all have two copies of this gene. If either or both Hex-A genes are active, the body produces enough of the enzyme to prevent the abnormal build-up of the GM2 ganglioside lipid. Carriers of Tay-Sachs - people who have one copy of the inactive gene along with one copy of the active gene - are healthy. They do not have Tay-Sachs disease but they may pass on the faulty gene to their children.

Carriers have a 50 percent chance of passing on the defective gene to their children. A child who inherits one inactive gene is a Tay-Sachs carrier like the parent. If both parents are carriers and their child inherits the defective Hex-A gene from each of them, the child will have Tay-Sachs disease. When both parents are carriers of the defective Tay-Sachs gene, each child has a 25 percent chance of having Tay-Sachs disease and a 50 percent chance of being a carrier...Read more about Tay-Sachs Disease NIH - National Human Genome Research Institute

What works? Research summarized

Evidence reviews

Hematopoietic Stem-Cell Transplantation in the Pediatric Population [Internet]

Assess comparative benefits and harms of hematopoietic stem-cell transplantation (HSCT) versus standard therapies or disease natural history in pediatric (age ≤21 years) patients with malignant solid tumors, inherited metabolic diseases, or autoimmune diseases.

Diagnosis and Treatment of Obstructive Sleep Apnea in Adults [Internet]

Methods for diagnosing and treating obstructive sleep apnea (OSA) are cumbersome, resource-intensive, and often inconvenient for the patient.

Terms to know

Enzymes
Protein made by the body that brings about a chemical reaction - for example, the enzymes produced by the gut to aid digestion.
Gangliosides
A complex molecule that contains both lipids (fats) and carbohydrates (sugars) and is found in the plasma (outer) membrane of many kinds of cells. Several different types of gangliosides have been identified.
Genetic
Inherited; having to do with information that is passed from parents to offspring through genes in sperm and egg cells.
Lipids
A term for fat in the body. Lipids can be broken down by the body and used for energy.
Neurons (Nerve Cells)
A type of cell that receives and sends messages from the body to the brain and back to the body. The messages are sent by a weak electrical current. Also called nerve cell.

More about Tay-Sachs Disease

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Also called: TSD

Other terms to know: See all 5
Enzymes, Gangliosides, Genetic

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