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Diagnostic Services

Genetics Lab


GM2 Gangliosidosis (Tay Sachs) Enzyme Assay

Hexosaminidase A deficiency results in a group of neurodegenerative disorders caused by the accumulation of a cellular lipid called GM 2 ganglioside. This glycosphingolipid accumulates in the lysosomes of many tissues causing progressive weakness and neurological deterioration. Seizures, loss of milestones and loss of vision is also common.

The disorders range from acute infantile onset and rapid decline (classic Tay Sachs disease) to juvenile, chronic and adult-onset forms. The diagnosis of hexosaminidase A deficiency is characterized by absent or profoundly deficient beta-hexosaminidase A activity in the presence of normal beta-hexosaminidase B activity.

Test Name: GM2 Gangliosidosis (Tay Sachs) (Hexosaminidase + %A) Serum
Test Code:
Test Description:
Spectrophotometric assay of beta-hexosaminidase A & B plus the percentage activity of beta-hexosaminidase A in serum.
Tay Sachs Disease, GM 2 gangliosidosis; hexosaminidase
This test is indicated for:
-infants and children with progressive weakness, loss of milestones, seizures, and general neurological decline
-adults with muscle weakness, dystonia and/or psychosis
Related Tests:
Clinical Links: Hexosaminidase A Deficiency GeneReview
Performed weekly
Turnaround Time:
7 days
Spectrophotometric enzyme assay
Reference Range:
Interpretive report provided
Consent Form:
Sample Requirements: Type
Whole Blood: 1-2ml red or gold top tube
Fibroblasts: 2 T-25 flasks
Skin Biopsy:2-4mm skin punch biopsy

Spin and freeze serum.
Do not freeze biopsy or cultured cells.

Ship serum frozen, overnight. Transport fibroblasts/biopsy in appropriate transport media.
Samples Received:
Mon - Fri 8:00am - 5:00pm PST. For Thursday shipping please arrange for AM courier delivery.
Special Considerations:
I-cell disease and Sandhoff disease can also be detected by this method.
Please e-mail Client Services or call at 206-987-2617 with any billing questions
CPT Code:
Please e-mail Client Services or call at 206-987-2617 with any billing questions