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Tay–Sachs disease is inherited in an autosomal recessive pattern. The HEXA gene is located on the long (q) arm of human chromosome 15, between positions 23 and 24. Tay–Sachs disease is an autosomal recessive genetic disorder, meaning that when both parents are carriers, there is a 25% risk of giving birth to an affected child with each ...
The diseases are better known by their individual names: Tay–Sachs disease, AB variant, and Sandhoff disease. Beta-hexosaminidase is a vital hydrolytic enzyme, found in the lysosomes, that breaks down lipids. When beta-hexosaminidase is no longer functioning properly, the lipids accumulate in the nervous tissue of the brain and cause problems.
This fatal genetic disorder is called Tay-Sachs disease. Because the Tay-Sachs gene defect mainly affects neural cells, a patient with the HEXA mutation will experience a quick deterioration of motor and mental function before dying around the age of three or four. [citation needed]
Mutations in genes coding for these enzymes leads to the accumulation of partially broken down gangliosides in lysosomes, which results in a group of diseases called gangliosidosis. For example, the fatal Tay–Sachs disease arises as a genetic defect which leads to no functional hexosaminidase A produced, causing GM2 to accumulate in lysosomes.
Tay–Sachs disease. In addition to its classic infantile form, Tay Sachs disease may present in juvenile or adult onset forms, often as the result of compound heterozygosity between two alleles, one that causes the classic infantile disease in homozygotes and another that allows some residual HEXA enzyme activity.
Enzyme replacement therapy is available to treat mainly Fabry disease and Gaucher disease, and people with these types of sphingolipidoses may live well into adulthood. The other types are generally fatal by age 1 to 5 years for infantile forms, but progression may be mild for juvenile- or adult-onset forms.
Generally, the other types are fatal by age 1 to 5 years for infantile forms, but progression may be mild for juvenile-onset or adult-onset forms. [citation needed] Alternatively, some of the sphingolipidoses may be classified into either GM1 gangliosidoses or GM2 gangliosidoses. Tay–Sachs disease belongs to the latter. [citation needed]
People with Tay–Sachs disease are unable to remove the GalNAc residue from the G M2 ganglioside, and as a result, they end up storing 100 to 1000 times more G M2 gangliosides in the brain than the unaffected person. Over 100 different mutations have been discovered just in infantile cases of Tay–Sachs disease alone. [11]