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"What is TAY-SACHS?" The classical form of TAY-SACHS disease (TSD) is a fatal genetic disorder in children that causes progressive destruction of the central nervous system. Tay-Sachs disease is a terminal metabolic (degenerative) disorder with a life expectancy of 2-5 years. This lipid storage disease attacks the Central Nervous System resulting in blindness, deafness, retardation, paralysis, and ultimately... DEATH! DISCOVERY OF TAY-SACHS The disease is named for Warren Tay (1843-1927), a British ophthalmologist who in 1881 described a patient with a cherry-red spot on the retina of the eye. It is also named for Bernard Sachs (1858-1944), a New York neurologist whose work several years later provided the first description of the cellular changes in Tay-Sachs disease. Sachs also recognized the familial nature of the disorder, and, by observing numerous cases, he noted that most babies with Tay-Sachs disease were of eastern European Jewish origin. 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. To date, there is no cure or effective treatment for TSD. However, there is active research being done in many investigative laboratories in the U.S. and around the world. The uses of enzyme replacement therapy to provide the Hex-A which is missing in babies with TSD has been explored. Although this approach is promising, scientists still face serious obstacles. Because the disease affects brain cells which are protected by the blood-brain barrier, enzymes like Hex-A are blocked from entering the brain from the blood. Bone marrow transplantation has also been attempted but to date has not been successful in reversing or slowing damage to the central nervous system in babies with TSD.
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