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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.
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.
A test to measure hexosaminidase A is done to:
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.
The health professional taking a sample of your blood will:
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little chance of a problem from having a blood sample taken from a vein.
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
If you had a recent blood transfusion, you may not be able to have the test, or the test results may not be helpful. If you have a blood transfusion from a blood donor who has normal levels of hexosaminidase A, your level may temporarily be higher than usual.
To help you understand the importance of this test, fill out the medical test information form.( What is a PDF document? )
Current as of:
April 1, 2019
Author: Healthwise StaffMedical Review: Sarah Marshall MD - Family MedicineMartin J. Gabica MD - Family MedicineE. Gregory Thompson MD - Internal MedicineAdam Husney MD - Family MedicineKathleen Romito MD - Family MedicineSiobhan M. Dolan MD, MPH - Reproductive Genetics
Current as of:
April 1, 2019
Medical Review:Sarah Marshall MD - Family Medicine & Martin J. Gabica MD - Family Medicine & E. Gregory Thompson MD - Internal Medicine & Adam Husney MD - Family Medicine & Kathleen Romito MD - Family Medicine & Siobhan M. Dolan MD, MPH - Reproductive Genetics
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