TAY SACHS DISORDER
What is Tay Sachs?
Tay Sachs, or GM2 gangliosidosis, is a rare disorder that keeps the body from developing a necessary fatty-acid destroying enzyme. This disorder is most commonly found in babies, and is a hereditary condition. There is no known cure, and affected children usually don't live past the age of five.
How is this Disorder Inherited?
The HEX A gene, which is carried on chromosome 15, breaks down fatty proteins (or in this case, the hexosaminidase A protein) and keeps the nervous system maintained. Tay Sachs is caused by a mutation of that gene. Without the gen working properly, the build-up of the hexosaminidase protein can become toxic, and cause death. The disorder is autosomal recessive, so the only way it can be passed is by carrier parents.
What are the Symptoms?
The symptoms, which start at only six months old, include loss of vision, poor motor skills, and bad hearing. A red spot may develop in the back of the child's eye. Seizures and lack of movement follow, starting at the age of two. Eventually, around the age of five, paralysis or even death may occur. All of the symptoms are due to the build up of the hexosaminidase A protein, which blocks the nervous system.
Is the Disorder Variably Expressed?
Tay Sachs is mostly past through the Ashkenazi Jewish population, and 1 in 27 Jews are carriers of it. Recently, the disorder has been seen in French Canadians and Cajuns as well. This is because these groups are, for the most part, isolated from other genes. This is due to the Founder Effect, which means that this large group of people are descendants from the same founders. Incidentally, some of the founders must have carried the genetic mutation, and passed it down. There are no environmental factors that play a role in the Tay Sachs mutation.
Pre-Birth Tay Sachs Detection
If a couple is unsure if their child will be affect by Tay Sachs, they can be blood tested for the cause of the mutated gene. While pregnant, women can have their child tested for it through Chorionic Villus Sampling, or CVS, in which a cell sample is drawn from the placenta. If hex A is not present in the cell, the child has the disorder.
Unfortunately, there is no known cure for this disorder. It can be detected before birth, but there is no way to cure the child. There are medicines for hiding the symptoms, but death is inevitable.