Tay-Sachs Disease

Tay-Sachs disease is a genetic disease that causes progressive deterioration of nerve cells, mental and physical abilities. It is an autosomal recessive genetic disease which means that an affected child would need to have inherited a mutated gene from both parents. The mutation is in the α-subunit locus on chromosome 15 which results in a deficiency of the enzyme hexosaminidase A. This enzyme is required to catabolize GM2 gangliosides. If a substance is not properly broken down, it can accumulate within lysosomes – the organelle that normally gets rid of unwanted substances within cells. This means that in an individual with Tay-Sachs disease, their lysosomes are filled with incompletely digested gangliosides. These lysosomes can become so large that they can interfere with normal cell functions. The brain is rich in gangliosides and so there is plenty of work to be done clearing them. In Tay-Sachs diesase with the defective hydrolysis of GM2 gangliosides, the accumulation occurs within neurons causing neurological symptoms.

Tay-Sachs disease can be classified into three main groups: infantile, juvenile or adult/late onset Tay-Sachs diesase. For patients with infantile Tay-Sachs, death will usually occur before the age of four and for juvenile Tay-Sachs disease, before the age of fifteen.  The incidence rate differs between different communities, with Ashkenazi Jews having one of the highest incidence rates at 1 in 3,500 births. The general population in the United States has a much lower incidence rate at 1 in 320,000 births. Pre-implantation genetic diagnosis, as well as pre-natal screening can be used to prevent having a child with Tay-Sachs disease. Unfortunately, there is currently no treatment or cure for Tay-Sachs disease however supportive care can be given to ease symptoms. Research into treatment is being directed in the area of trying to replace the defective enzyme: hexosaminidase A, or to increase the activity of it, in order to slow deterioration of those with the disease. Investigation is also underway to try to reduce the amount of substrate the enzyme needs to metabolise (GM2 gangliosides), which would lead to less build up of substrate, so that levels of it are not an issue.

If you are interested in helping to find a cure for this disease, please visit: http://www.curetay-sachs.org/

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