What is Tay-Sachs disease?
Tay-Sachs disease is a genetic disorder of lipid (fat) metabolism resulting from a missing enzyme. This enzyme normally breaks down special nerve lipids known as gangliosides, which are present in the brain and spinal cord. These substances accumulate and destroy the cells, often killing the child by age three or four years.
Several features at birth may raise the possibility of early detection, particularly cherry-red spots on the retina of the eye. Most newborns with Tay-Sachs disease, however, appear normal at birth. Between the ages of three months and six months, the progressive neurologic damage becomes apparent: deafness, blindness, muscle paralysis, and developmental disorders. By eighteen months, the infant is usually already in a vegetative state, requiring complete care. The child may survive until three or four years of age, dying from complications associated with comatose and bedridden patients, usually infections.
Tay-Sachs disease has no cure, and only supportive measures can be used. Feeding tubes for nutrition and fluids, suctioning of throat secretions, meticulous skin care for bed sores, and oxygen to assist breathing are among the types of support needed. Full-time skilled nursing care at home or at a facility is often necessary.
While Tay-Sachs disease is the most common lipid (or lysosomal) storage disease, it is rare in the general population—about one in 250 people carry the genetic mutation that causes Tay-Sachs. It is much more common, however, in people of Ashkenazi (Eastern European) Jewish ancestry, as well as those of French Canadian and Cajun ancestry. Among these populations, approximately one person in twenty-seven is a carrier of the genetic defect. If two such carriers have children, they have a 25 percent chance of having a child with Tay-Sachs disease. Prenatal testing using amniocentesis or chorionic villus sampling can detect affected fetuses. More important is genetic counseling and screening of couples with a family history. A blood test can identify carriers.
Ongoing research is attempting to correct the disease in the developing fetus through the insertion of the missing gene.
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