Tay-Sachs Test

Serum Hexosaminidase A and B

Results

The test for Tay-Sachs disease measures the amount of an enzyme called hexosaminidase A (hex A) in the blood.

Normal

Tay-Sachs test

	Enzyme measured	Value
Amount in blood	Total hexosaminidase (A+B):	9.9–15.9 units per liter (U/L)
Amount in blood	Hexosaminidase A:	7.5–9.8 units per liter (U/L)

• Normal values vary depending on the laboratory and test method used. Check with your doctor for normal values.
• A person who has about half the normal amount of hex A is a Tay-Sachs carrier.
• A person who does not have any hex A has Tay-Sachs disease.
• In rare cases, a person may not have either hex A or hex B enzyme. This causes a more severe condition called Sandhoff's disease.

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Author:	Debby Golonka, MPH	Last Updated: March 31, 2008
Medical Review:	Michael J. Sexton, MD - Pediatrics Siobhan M. Dolan, MD, MPH - Reproductive Genetics
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