"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
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.
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.
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.