What is Tay Sachs, AB Variant?
Tay Sachs, AB Variant is a rare inherited disorder that causes progressive destruction of nerve cells in the brain and spinal cord (the central nervous system). Clinically, Tay Sachs, AB Variant is identical to Tay Sachs disease.
What other names are used for Tay Sachs, AB Variant?
Some of the other common names for Tay Sachs, AB Variant include:
- GM2-gangliosidosis, AB Variant
- AB Variant
- Activator-deficient Tay Sachs disease
- GM2 Activator Deficiency disease
- GM2 gangliosidosis, type AB
- Hexosaminidase activator deficiency
A baby with Tay-Sachs, AB Variant disease appears normal at birth and seems to develop normally until about 6 months of age. Around 6 months of age, development slows and the child exhibits an abnormal startle response. The infant gradually regresses, losing skills one by one, and is eventually unable to crawl, turn over, sit, or reach out. By about 2 years of age, most children experience recurrent seizures and diminishing mental function. 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. Death usually occurs between ages 2 and 5 from pneumonia and breathing difficulties.
How common is Tay Sachs, AB Variant?
The AB Variant is extremely rare; only a few cases have been reported worldwide.
What genes are related to Tay Sachs, AB Variant?
Mutations in the GM2A gene cause Tay Sachs, AB Variant.
The GM2A gene provides instructions for making a protein called the GM2 ganglioside activator. This protein is required for the normal function of hexosaminidase A (Hex-A), a critical enzyme in the central nervous system. Hex-A is needed for the body to break down a fatty waste substance found in brain cells, GM2 ganglioside.
If mutations disrupt the activity of the GM2 ganglioside activator, Hex-A cannot perform its normal function and GM2 ganglioside can accumulate to toxic levels in the brain and spinal cord. Progressive damage caused by the buildup of this substance leads to the destruction of nerve cells, which causes the severe medical problems characteristic of the AB Variant.
How does a child inherit Tay Sachs, AB Variant?
Tay Sachs, AB Variant is a genetically inherited disorder, passed on from the parents to their biological child. Most often, the parents each carry one copy of the mutated gene, but do not show signs or symptoms of the condition and live a perfectly normal life. When two carriers of Tay Sachs, AB Variant become parents, there is 1 in 4 chance that any child will inherit a Tay Sachs, AB Variant gene from each parent and have the fatal disease.
Is there any treatment for Tay Sachs, AB Variant?
Presently there is no treatment for Tay Sachs, AB Variant. Anticonvulsant medicine may initially control seizures. A feeding tube may be needed. Affected children can only be made as comfortable as possible. Gene therapy research may eventually lead to a cure or treatment to slow the progression of Tay Sachs, AB Variant.