Tay-Sachs disease is caused by a deficiency of hexosaminidase, an enzyme that is important in the metabolism of gangliosides (a type of chemical substance found in nerve tissue). These gangliosides, particularly ganglioside GM2, then accumulate in the brain, causing neurological deterioration. Tay-Sachs disease is inherited as a recessive gene, and 1 in 25 members of the Ashkenazi Jewish population carries the gene. Tay-Sachs has been classified into infantile, juvenile, and adult forms, depending on the type of symptoms and when they first appear. The majority of people with Tay-Sachs have the infantile form. Symptoms generally begin to appear when the child is 3 - 6 months old. The disease tends to progress rapidly, and the child usually dies by the age of 4 or 5 years.
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