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Tay-Sachs Disease By Andy Page

In 1887, Harvard-trained American neurologist Bernard Sachs described, for the first time, the cellular changes caused by a usually fatal genetic disorder found in infants in New York hospitals. A few years earlier, the British ophthalmologist Warren Tay had identified cherry-red spots on the retinas of patients who suffered from this disease. The disorder named for the two physicians, Tay-Sachs disease, is a rare inherited condition that causes progressive destruction of nerve cells in the brain and spinal cord.
Infants with Tay-Sachs disease appear to develop normally for the first few months of life. Then, as nerve cells become distended with fatty material, a deterioration of mental and physical abilities occurs. The first signs of Tay-Sachs can vary and are manifest at different ages in affected children. Initially, development slows, there is a loss of peripheral vision, and the child exhibits an abnormal startle response. Gradually, the infants lose motor skills and mental functions. Over time, the child becomes blind, deaf, mentally retarded, and non responsive to the environment. Muscles begin to atrophy and paralysis sets in. Children with the disease usually die by age four or five. In addition to infantile Tay-Sachs, there are much rarer juvenile and adult onset forms of the disease.
Sachs also noticed the familial nature of the disease. Tay-Sachs is much more common in Eastern European Jewish (Ashkenazi) populations, with 1 out of 27 American Jews being a recessive carrier of the disease. Louisiana Cajuns and Irish Americans also have an increased prevalence of the disorder, and French Canadians have a carrier frequency similar to Ashkenazi Jews, but they carry a different mutation.
Tay-Sachs disease is caused by mutations in the HEX-A gene. This gene provides instructions for making part of an enzyme called beta-hexosaminidase A, which plays a critical role in the central nervous...