Tay-Sachs disease is caused by the absence of a vital enzyme called hexosaminidase A (Hex-A). Without Hex-A, a fatty substance or lipid called GM2 ganglioside accumulates abnormally in cells, especially in the nerve cells of the brain. This ongoing accumulation causes progressive damage to the cells. The destructive process begins in the fetus early in pregnancy, although the disease is not clinically apparent until the child is several months old. By the time a child with TSD is three or four years old, the nervous system is so badly affected that life itself cannot be supported. Even with the best of care, all children with classical TSD die early in childhood, usually by the age of five.

A baby with Tay-Sachs disease appears normal at birth and seems to develop normally until about six months of age. The first signs of TSD can vary and are evident at different ages in affected children. Initially, development slows, there is a loss of peripheral vision, and the child exhibits an abnormal startle response. By about two years of age, most children experience recurrent seizures and diminishing mental function. The infant gradually regresses, losing skills one by one, and is eventually unable to crawl, turn over, sit, or reach out. Other symptoms include increasing loss of coordination, progressive inability to swallow and breathing difficulties. Eventually, the child becomes blind, mentally retarded, paralyzed, and non-responsive to his or her environment.

(Source: National Tay-Sachs and Allied Disesases Association.)

For more information about Tay-Sachs and the other related diseases, visit the NTSAD website at www.ntsad.org.