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 out of every 25 members of the Ashkenazi Jewish population carries the gene. The incidence is 1 out of 2,500 people in this population.
Depending on the age of onset and clinical features, Tay-Sachs has been classified into infantile-, juvenile-, and adult-onset forms. The majority of people with Tay-Sachs, however, have infantile forms.
Symptoms begin to appear at 3 to 6 months old. The disease unfortunately tends to progress rapidly, and the child usually dies by the age of 4 or 5 years.
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