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Hexosaminidase A and Total
MessageThis test is NOT useful for pregnant females or those treated with hormonal contraception.
Test Code
LAB01192
Alias/See Also
LAB01192
Mayo TC: NAGS
Mayo Test Name: Hexosaminidase A and Total Hexosaminidase, Serum
Sandhoff
Tay Sachs
Mayo TC: NAGS
Mayo Test Name: Hexosaminidase A and Total Hexosaminidase, Serum
Sandhoff
Tay Sachs
CPT Codes
83080 (x2)
Preferred Specimen
1.0 mL Serum
(Marble, Gold, Red)
(Marble, Gold, Red)
Minimum Volume
0.5 mL Serum
Transport Temperature
Refrigerated
Specimen Stability
Refrigerated: 7 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross icterus
Methodology
Heat Inactivation, Fluorometric, Automated
Report Available
8-14 days
Limitations
GM2 activator deficiency (AB variant, GM2A) is a rare disorder with clinical features similar to Tay-Sachs and Sandhoff diseases; however, levels of both hexosaminidase A and B are normal. GM2 activator deficiency is not detected with this assay.
Reference Range
Hexosaminidase Total:
< or =15 years: > or = 20 nmol/min/mL
> or =16 years: 10.4-23.8 nmol/min/mL
Hexosaminidase Percent A
< or =15 years: 20-90%
> or =16 years: 56-80%
Interpretation is provided with report.
< or =15 years: > or = 20 nmol/min/mL
> or =16 years: 10.4-23.8 nmol/min/mL
Hexosaminidase Percent A
< or =15 years: 20-90%
> or =16 years: 56-80%
Interpretation is provided with report.
Clinical Significance
Tay-Sachs and Sandhoff diseases, also referred to as GM2 gangliosidoses, are lysosomal storage disorders caused by deficiencies of the enzymes hexosaminidase A and hexosaminidase B, respectively. These isoenzymes are dimers that differ in their subunit composition. Hexosaminidase A is a heterodimer composed of 1 alpha and 1 beta subunit (alpha-beta), while hexosaminidase B is a homodimer composed of 2 beta subunits (beta-beta). The defective lysosomal degradation and the excessive accumulation of GM2 ganglioside and related glycolipids result in the development of the clinical symptomology observed in Tay-Sachs and Sandhoff diseases.
Tay-Sachs and Sandhoff diseases are autosomal recessive conditions. Tay-Sachs disease results from 2 varients in HEXA, which encodes for the alpha subunit of hexosaminidase and causes a deficiency of hexosaminidase A enzyme. An increased carrier frequency for Tay-Sachs disease is observed in individuals of Ashkenazi Jewish, Celtic, and French-Canadian ancestry. Patients with Sandhoff disease have 2 variants in HEXB, which encodes for the beta subunit of hexosaminidase and results in deficiencies in both hexosaminidase A and hexosaminidase B enzymes. Sandhoff disease does not exhibit an increased carrier frequency in any specific population.
Tay-Sachs and Sandhoff diseases are autosomal recessive conditions. Tay-Sachs disease results from 2 varients in HEXA, which encodes for the alpha subunit of hexosaminidase and causes a deficiency of hexosaminidase A enzyme. An increased carrier frequency for Tay-Sachs disease is observed in individuals of Ashkenazi Jewish, Celtic, and French-Canadian ancestry. Patients with Sandhoff disease have 2 variants in HEXB, which encodes for the beta subunit of hexosaminidase and results in deficiencies in both hexosaminidase A and hexosaminidase B enzymes. Sandhoff disease does not exhibit an increased carrier frequency in any specific population.
Performing Laboratory
Mayo Clinic Laboratories