Skip to content

    Health & Baby

    Font Size
    A
    A
    A

    Tay-Sachs Test

    The test for Tay-Sachs disease measures the amount of an enzyme 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 nerve cells of the brain and damage them.

    Tay-Sachs can occur when parents pass on a changed gene to their child.

    • If the baby gets the changed gene from both parents, he or she will get the disease.
    • If the baby gets the changed gene from only one parent, he or she will be a carrier. 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 changed 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 condition called Sandhoff's disease.

    The Tay-Sachs enzyme test is usually done on blood taken from a vein or from the umbilical cord right after birth.

    Why It Is Done

    A test to measure hexosaminidase A is done to:

    • See whether a baby has Tay-Sachs disease.
    • Find Tay-Sachs carriers. People of Ashkenazi Jewish, French-Canadian, or Cajun descent who have a family history of Tay-Sachs disease or who live in a community or population with a high amount of Tay-Sachs disease may want to be tested.
    • See whether an unborn baby (fetus) has Tay-Sachs disease. This is done early in pregnancy using amniocentesis or chorionic villus sampling.

    How To Prepare

    You do not need to do anything before having this test. If you are having this test to see whether you are a Tay-Sachs carrier, you should tell your doctor if you have had a blood transfusion in the past 3 months.

    Talk to your doctor about any concerns you have about the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

    1 | 2 | 3

    WebMD Medical Reference from Healthwise

    Last Updated: August 07, 2014
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

    Today on WebMD

    mother on phone holding baby
    When you should call 911.
    parents and baby
    Unexpected ways your life will change.
     
    baby acne
    What’s normal – and what’s not.
    baby asleep on moms shoulder
    Help your baby get the sleep he needs.
     

    mother holding baby at night
    ARTICLE
    mother with sick child
    QUIZ
     
    Chinese mother breast feeding newborn baby girl
    SLIDESHOW
    Track Your Babys Vaccines
    TOOL
     
    Baby Napping 10 Dos And Donts
    Slideshow
    Mother with her baby boy
    Article
     
    baby in crib
    Slideshow
    baby gear slideshow
    Slideshow