Hexosaminidase A and Total, Leukocytes/Molecular Reflex, Whole Blood
Use
This test is essential for the carrier detection and diagnosis of Tay-Sachs disease and Sandhoff disease. Both are lysosomal storage disorders caused by deficiencies of hexosaminidase A and B enzymes, leading to the accumulation of GM2 ganglioside and clinical symptoms. This test measures enzyme activity levels, indicates the necessity of reflex testing with next-generation sequencing for HEXA or HEXB genes, and differentiates between possible carrier, affected, and non-disease-causing pseudodeficiency alleles. Enzyme analysis helps distinguish between Tay-Sachs and Sandhoff diseases.
Special Instructions
Not provided.
Limitations
A small percentage of carriers with normal hexosaminidase A activity may not be detected by this test. GM2 activator deficiency, a rare disorder with clinical features similar to Tay-Sachs and Sandhoff diseases, cannot be detected with this assay. Regions in genes with homology, high GC content, or repetitive sequences may not be effectively evaluated. Variant confirmation may require alternate methodologies as determined by internal criteria.
New York Approved
Methodology
Other
Biomarkers
Hexosaminidase A
ProteinHexosaminidase B
Protein
LOINC Codes
- 87543-5 - Hex A & Total w Rflx HEXA Pnl WBC-cCnt
- 24075-4 - B-NAH WBC-cCnt
- 23825-3 - Hexosaminidase A CFr WBC
- 59462-2 - Clinical biochemist review
- 18771-6 - Provider signing name
Result Turnaround Time
2-8 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
6 mL
Minimum Volume
5 mL
Container
Yellow top (ACD solution B preferred, solution A acceptable)
Collection Instructions
Send whole blood specimen in original tube. Do not aliquot.
Storage Instructions
Refrigerate within 6 days of collection to stabilize leukocytes.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 6 days |
| Refrigerated | 6 days |