The test for Reference Tay-Sachs disease Opens New Window measures the amount of an Reference enzyme Opens New Window called hexosaminidase A (hex A) in the blood. Hex A breaks down fatty substances in the brain and nerves. Tay-Sachs is an inherited disease in which the body can't break down fatty substances as it should, so the fatty substances collect in the body and damage brain and nerve cells.
Tay-Sachs can occur when parents pass on a changed gene to their child.
- If the baby gets the gene from both parents, he or she will get the disease.
- If the baby gets the gene from only one parent, he or she will be a Reference carrier Opens New Window. This means that the child will have one gene that produces hex A and one that doesn't. The child's body makes enough hex A so that he or she doesn't get the disease. But the child can pass the gene on to his or her children.
A Tay-Sachs test may also measure the amount of another enzyme, called hexosaminidase B. People who cannot make either hex A or B have a rare, more serious condition called Sandhoff's disease.
The Tay-Sachs test is usually done on blood taken from a vein or from the umbilical cord right after birth. It can also be done on a sample of Reference amniotic fluid Opens New Window (collected during Reference amniocentesis Opens New Window) or on cells from the Reference placenta Opens New Window (collected during Reference chorionic villus sampling Opens New Window).
|By:||Reference Healthwise Staff||Last Revised: Reference September 6, 2011|
|Medical Review:||Reference Sarah Marshall, MD - Family Medicine
Reference Siobhan M. Dolan, MD, MPH - Reproductive Genetics