Tay-Sachs Disease

Exams and Tests

If your baby is suspected of having Tay-Sachs disease, a physical examination may reveal or confirm symptoms of the disease. A blood test (Tay-Sachs screen test) can determine whether your baby's body is producing the enzyme hexosaminidase A. The blood sample can be taken from a vein or from the umbilical cord immediately after birth.

If you are pregnant and are at risk for having a child with Tay-Sachs disease, the Tay-Sachs screen test can be done on a blood sample collected from the placenta during chorionic villus sampling or on a sample of amniotic fluid collected during amniocentesis. For more information, see the medical tests Amniocentesis and Chorionic Villus Sampling.

The Tay-Sachs screen test is also used to confirm late-onset Tay-Sachs disease in a teen or adult with symptoms of the disease.

A positive Tay-Sachs test may need to be confirmed with other genetic tests. For more information, see the medical test Genetic Test.

Screening for carriers

Knowing whether you are a carrier of Tay-Sachs disease is important, because Tay-Sachs is an autosomal recessive disease. If you are a carrier, you have the Tay-Sachs trait but not the disease. You have one chromosome that produces hexosaminidase A and one that does not produce this enzyme. Your body probably makes about 50% of the normal level of hex A, which prevents you from getting the disease; however, you can pass the trait on to your children. If both you and your spouse are carriers, there is a 1-in-4 chance (25%) that any child you have will have Tay-Sachs disease.

If you are considering having a child, the American College of Obstetricians and Gynecologists (ACOG) recommends that:¹

• Both prospective parents be screened if both of you are Ashkenazi Jews or of French-Canadian or Cajun descent or have a family history of the disease. If both of you test positive as carriers, you should consider genetic counseling.
• You or your partner be screened if either of you is an Ashkenazi Jew or of French-Canadian or Cajun descent or has a family history of the disease. If one of you tests positive for the trait, the other partner should be screened.

Recently, one study compared testing for hexosaminidase A with testing DNA directly for Tay-Sachs disease. Evidence indicates that DNA testing is the most cost-effective and efficient approach to carrier screening.²

Go to previous section	Go to top of page	Go to next section
Author:	Sabra L. Katz-Wise	Last Updated: April 14, 2006
Medical Review:	Michael J. Sexton, MD - Pediatrics Renee H. Martin, PhD - Medical Genetics
© 1995-2008 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.