Tay Sachs Disease is a rare genetic disease in which the absence of a key protein results in the build-up of fatty substances. These fatty substances called gangliosides will become toxic in the body ultimately resulting in death around five years of age. This disease is not curable due to it being a result of a genetic mutation passed down by parents.
Tay Sachs is mostly a result of an in-frame deletion of 192 codons in the HEXA gene, located on chromosome 15q23. Although there are other causes of Tay Sachs disease, this seems to be the most common mutation (Gene bank accession number KR710352).
The HEXA gene is responsible for the production of a key enzyme called Beta-Hex0saminadase A. This enzyme, when normally synthesized is found in the lysosomes of nerve cells in your brain and spinal cord. Their function is to break down apart GM2 Gangliosides that accumulate in the cell. Their inability to synthesize these lipids results in the build-up of unmetabolizable and toxic GM2 Gangliosides in lysosomes.
How Is It Passed Down?
Since this disease is a result of a genetic mutation, you are not able to “catch” it from someone that has Tay Sachs. Instead, you must inherit it from your parents, just as you inherit your eye and hair color.
In this case, Tay Sachs is an autosomal recessive gene-disease. This means that both copies on both chromosomes have to have the gene mutation for this disease to be expressed. In other words, both of your parents must have one chromosome that has this mutation for an offspring to obtain this mutation. This also means that there is a 25% chance of inheriting this disease if two parents that are heterozygous for this mutation.
But, you may be asking why the parents that have this mutation do not know? Although it is possible to know you have this mutation if you take a PCR test, there is no other way to tell. People that are heterozygous for this mutation have no disease manifestation and can live their life normally.
So, why is this mutation so prominent? This mutation is thought to be a result of heterozygous evolution and advantageous results. People that are heterozygous for this mutation have an increased immune response to diseases like tuberculosis.
People that experience this disease will be a victim of numerous physical and mental disabilities. The most common include the loss of motor control due to the increase of GM2 Gangliosides building up in nerve cells. This destroys nonreproducible cells that function for motor control that is involuntary and voluntary.
Other symptoms include seizures, loss of vision and hearing, muscle weakness, and paralysis. There are treatments and medication to help combat these symptoms, however. Things such as medication, feeding tubes, physical therapy, and respiratory care can help manage and make these symptoms less frequent.
How Do You Identify Tay Sachs?
There are a few physical signs that may be a result of Tay Sachs. The most common is called Cherry red spots in the eyes. These are circular discolored areas in the posterior portion of the eye that is a result of lipid buildup and nerve damage. Other things such as the inability to lift their head at the proper age can also be signs. Genetic and blood tests can be used to further identify what problems are going on in the body, but it is always important to follow up with a professional.
People that are more likely to have this mutation include descents of:
- Ashkenazi Jewish
- French Canadian
- Pennsylvania Dutch