However, increased education and genetic testing efforts in these at-risk communities have reduced the incidence of this condition in those populations. The variants responsible for this disease are also more common in certain French-Canadian communities of Quebec, the Old Order Amish community in Pennsylvania, and the Cajun population of Louisiana.
The HEXA gene provides instructions for making one part the alpha subunit of an enzyme called beta-hexosaminidase A. Beta-hexosaminidase A is located in lysosomes , which are structures in cells that break down toxic substances and act as recycling centers. Within lysosomes, beta-hexosaminidase A helps break down a fatty substance called GM2 ganglioside found in cell membranes.
As a result, GM2 ganglioside accumulates to toxic levels, particularly in neurons in the central nervous system. Damage caused by the buildup of GM2 ganglioside leads to the dysfunction and eventual death of these neurons, which causes the signs and symptoms of Tay-Sachs disease. HEXA gene variants that eliminate or severely reduce beta-hexosaminidase A enzyme function likely lead to the infantile form of Tay-Sachs disease, and variants that allow some residual enzyme activity tend to cause the juvenile or late-onset form of the condition.
Because Tay-Sachs disease impairs the function of a lysosomal enzyme and involves the buildup of GM2 ganglioside, this condition is sometimes referred to as a lysosomal storage disorder or a GM2-gangliosidosis.
This condition is inherited in an autosomal recessive pattern , which means both copies of the gene in each cell have variants. The parents of an individual with an autosomal recessive condition each carry one copy of the altered gene, but they do not show signs and symptoms of the condition. Genetics Home Reference has merged with MedlinePlus. Learn more. Content on this website is provided for information purposes only. Information about a therapy, service, product or treatment does not in any way endorse or support such therapy, service, product or treatment and is not intended to replace advice from your doctor or other registered health professional.
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Home Genetic conditions. Tay-Sachs disease. Actions for this page Listen Print. Summary Read the full fact sheet. On this page. What causes Tay-Sachs disease? Tay-Sachs disease TSD is a genetic condition that affects the nervous system. It is caused by an alteration in the HEXA gene on chromosome Males and females are equally affected.
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Health Conditions Discover Plan Connect. Tay-Sachs Disease. Medically reviewed by Kristen M. What is Tay-Sachs disease? What are the symptoms of Tay-Sachs? What causes Tay-Sachs?
What are the risk factors for Tay-Sachs? The parents are carriers of the gene. This means that they each have one of the genes for Tay-Sachs disease. Carriers of Tay-Sachs disease do not show any symptoms of it. A doctor may suspect Tay-Sachs when a baby has movement problems or stops doing things they used to do, like crawling or sitting up. Doctors can diagnose the condition by doing an exam and ordering blood tests.
Before or during a pregnancy, couples can get screened for the Tay-Sachs gene with a simple blood test. If both carry the Tay-Sachs gene, a genetic counselor can provide more information.
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