Tay-Sachs disease is the most well known Jewish genetic disease, potentially affecting one in every 2,500 Ashkenazi Jewish newborns. This disease is characterized by the onset of severe mental and developmental retardation during the first four to eight months of life. An early sign of the disease is the cherry-red spot, an unusual abnormality in the retina of the eye observed only by use of an ophthalmoscope. The involvement of the central nervous system progresses rapidly and affected children become totally debilitated by two to five years of life. Affected children also develop seizures which are not controllable with anti-epileptic drugs.
Death usually occurs by five to eight years of life due to pneumonia or other infections.
Tay-Sachs disease is an inherited metabolic disorder. This enzyme normally breaks down a naturally occurring fatty substance called GM2-ganglioside. The enzyme deficiency leads to a toxic accumulation of GM2-ganglioside in the cells of the nervous system. A has been isolated on chromosome 15 and several specific mutations which cause infantile Tay-Sachs disease in Ashkenazi Jewish individuals have been identified. Tay-Sachs disease is inherited in an autosomal recessive manner.