Hexosaminidase A and Total, Serum
Also known as: Tay-Sachs
Use
This enzyme assay quantifies total hexosaminidase activity and the percent of hexosaminidase A in serum, aiding in the diagnosis of Tay‑Sachs and Sandhoff diseases (GM2 gangliosidoses) and carrier screening. It provides diagnostic clarity for elevated total enzyme activity, as seen in I‑cell disease, and helps assess deficiency of hexosaminidase A activity in lysosomal storage disorders.
Special Instructions
New York State clients require informed consent; this must be documented on the requisition or electronic order. If serum results are ambiguous during pregnancy, leukocyte testing is recommended. Mayo Medical Laboratories offers a reflex test (Hexosaminidase A and Total, Leukocytes) for follow‑up as needed.
Limitations
Serum assay results may be ambiguous in pregnant individuals. The test does not detect GM2 activator deficiency (AB variant, GM2A), which presents with normal hexosaminidase A and B levels despite clinical overlap. Heat‑inactivation methodology may have limitations in rare variants; confirmatory testing by leukocyte enzyme analysis or molecular methods may be needed.
Methodology
Automated Analyzer (Other)
Biomarkers
Result Turnaround Time
8-15 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Serum gel (preferred); red‑top acceptable
Collection Instructions
Centrifuge and aliquot serum into plastic vial
Causes for Rejection
Grossly icteric
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 7 days |
| Frozen | 30 days |