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Tay-Sachs disease is a rare inherited disorder that causes progressive destruction of nerve cells in the brain and spinal cord (the central nervous system).
The most common form of Tay-Sachs disease begins in infancy. Infants with this disorder typically appear normal until the age of 3 to 6 months, when development slows and muscles used for movement weaken. Affected infants lose motor skills such as turning over, sitting, and crawling. They also develop an exaggerated startle reaction to loud noises. As the disease progresses, children with Tay-Sachs disease experience seizures, vision and hearing loss, mental retardation, and paralysis. An eye abnormality called a cherry-red spot, which can be identified with an eye examination, is characteristic of this disorder. Children with this severe infantile form of Tay-Sachs disease usually survive only into early childhood.
Other forms of Tay-Sachs disease are much rarer. Signs and symptoms can begin in childhood, adolescence, or adulthood and are usually milder than those seen with the infantile form of Tay-Sachs disease. As in the infantile form, mental abilities and coordination are affected. Characteristic features include muscle weakness, loss of muscle coordination (ataxia) and other problems with movement, speech problems, and mental illness. These signs and symptoms vary widely among people with late-onset forms of Tay-Sachs disease.
Tay-Sachs disease is very rare in the general population. The genetic mutations that cause this disease are more common in people of Ashkenazi (eastern and central European) Jewish heritage than in those with other backgrounds. In recent years, however, screening for mutations and genetic counseling have made the condition much less frequent in this population.
The genetic mutations that cause Tay-Sachs disease are also more common in certain French-Canadian communities of Quebec, the Old Order Amish community in Pennsylvania, and the Cajun population of Louisiana.
Mutations in the HEXA gene cause Tay-Sachs disease.
The HEXA gene provides instructions for making part of an enzyme called beta-hexosaminidase A, which plays a critical role in the central nervous system. This enzyme is located in cellular structures called lysosomes, which are the cell's recycling centers. Within lysosomes, beta-hexosaminidase A helps break down a fatty substance known as GM2 ganglioside. Mutations in the HEXA gene disrupt the activity of beta-hexosaminidase A, preventing the breakdown of this substance. As a result, it can accumulate to toxic levels in the brain and spinal cord. Progressive damage caused by the buildup of GM2 ganglioside leads to the destruction of nerve cells, which causes the signs and symptoms of Tay-Sachs disease.
Because Tay-Sachs disease impairs the function of a lysosomal enzyme and involves the buildup of GM2 ganglioside, this condition is sometimes referred to as a lysosomal storage disorder or a GM2-gangliosidosis.
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition.
'''Tay-Sachs disease''' (abbreviated '''TSD''') is a fatal genetic disorder, inherited in an autosomal recessive pattern, in which harmful quantities of a fatty substance called ganglioside GM2 accumulate in the nerve cells in the brain. The disease is named after the United Kingdom ophthalmologist Warren Tay who first described the red spot on the retina of the eye in 1881, and the American neurologist Bernard Sachs who described the cell (biology) changes of Tay-Sachs and noted an increased prevalence in the Eastern European Jewish population of 1887.
Molecular Genetics Testing Laboratory: Ashkenazi Jewish Genetic Disease Screen - Information about a test for seven common inherited diseases in the Ashkenazi Jewish population: Tay-Sachs disease, Canavan disease, cystic fibrosis, Gaucher disease, Bloom syndrome, familial dysautonomia and Fanconi anemia.
National Tay-Sachs and Allied Diseases Association - An organization offering support and programs geared to families affected by Tay-Sachs Disease and over 40 other fatal degenerative genetic disorders.
Tay-Sachs Disease - A description along with prognosis and treatment of this disease.
Tay-Sachs Disease - Information sheet on this disease addressing what it is, treatment and prognosis.
Tay-Sachs Disease - Discussion on what it is, how it is transmitted, are certain populations at higher risk, is there a test to see if one is a carrier and is there a way to prevent this disease.