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HelpTest Code NAGS Hexosaminidase A and Total Hexosaminidase, Serum
Reporting Name
Hexosaminidase A and Total, SUseful For
Carrier detection and diagnosis of Tay-Sachs disease and Sandhoff disease
Ruling out I-cell disease
This test is not useful for pregnant females or those treated with hormonal contraception.
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumOrdering Guidance
Testing for Tay-Sachs Disease and Sandhoff Disease
The following tests are available for diagnostic and carrier testing for Tay-Sachs and Sandhoff diseases.
NAGR / Hexosaminidase A and Total, Leukocytes/Molecular Reflex, Whole Blood:
-This is the recommended test for carrier testing for Tay-Sachs disease and Sandhoff disease.
-Testing begins with hexosaminidase A and total enzyme analysis. If the results are consistent with an affected or carrier for Tay-Sachs disease or Sandhoff disease, next generation sequencing to detect single nucleotide and copy number variants for HEXA or HEXB, respectively, will automatically be performed on the original specimen.
-This test is appropriate for males and pregnant or nonpregnant females.
NAGW / Hexosaminidase A and Total Hexosaminidase, Leukocytes:
-This test can be used for diagnosis and carrier testing for Tay-Sachs disease or Sandhoff disease.
-Results for hexosaminidase A and total enzyme analysis are reported with recommendations for additional testing when appropriate. All follow-up testing must be ordered separately on new specimens.
-This test is appropriate for males and pregnant or nonpregnant females.
NAGS / Hexosaminidase A and Total Hexosaminidase, Serum:
-This test can be used for diagnosis and carrier testing for Tay-Sachs disease or Sandhoff disease.
-Results for hexosaminidase A and total enzyme analysis are reported with recommendations for additional testing when appropriate.
-If results indicate normal, indeterminate, or carrier status and the suspicion of Tay-Sachs disease remains high, MUGS / Hexosaminidase A, Serum for Tay-Sachs disease (B1 variant) can typically be added and performed on the same specimen.
-With the exception of MUGS, all follow-up testing must be ordered separately on new specimens.
-This test is not appropriate for pregnant females or women receiving hormonal contraception. This test is appropriate for males and nonpregnant females.
-This test is particularly useful when it is difficult to obtain enough blood to perform leukocyte testing (NAGR or NAGW), as may be the case with infants.
MUGS / Hexosaminidase A, Serum:
-This is the recommended test for diagnosis and carrier testing for the B1 variant of Tay-Sachs disease. This test will not detect Sandhoff disease.
-This test should not be ordered as a first-line test. Rather, this test should be ordered when the NAGR, NAGW, NAGS indicate normal, indeterminate, or carrier results and the suspicion of Tay-Sachs disease remains high. In most cases, this test can be performed on the original specimen collected for NAGS.
Specimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into plastic vial.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Frozen (preferred) | 30 days | |
| Refrigerated | 7 days |
Special Instructions
Reference Values
Hexosaminidase total
≤15 years: ≥20 nmol/min/mL
≥16 years: 10.4-23.8 nmol/min/mL
Hexosaminidase percent A
≤15 years: 20-90%
≥16 years: 56-80%
Day(s) Performed
Thursday
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
83080 x 2
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| NAGS | Hexosaminidase A and Total, S | 87545-0 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 27612 | Hexosaminidase Total, S | 1956-2 |
| 27613 | Hexosaminidase Percent A, S | 12914-8 |
| 27216 | Interpretation (NAGS) | 59462-2 |
| 27218 | Reviewed By | 18771-6 |
Interpretation
Interpretation is provided with report.
Clinical Reference
1. Delnooz CCS, Lefeber DJ, Langemeijer SMC, et al. New cases of adult-onset Sandhoff disease with a cerebellar or lower motor neuron phenotype. J Neurol Neurosurg Psychiatry. 2010;81(9):968-972
2. Gravel RA, Kaback MM, Proia RL, Sandhoff K, Suzuki K, Suzuki K: The GM2 gangliosidoses. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw Hill; 2019. Accessed September 10, 2024. Available at https://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=225547784
3. Toro C, Shirvan L, Tifft C. HEXA Disorders. In: Adam MP, Everman DB, Mirzaa GM, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 1999. Updated October 1, 2020. Accessed September 10, 2024. Available at www.ncbi.nlm.nih.gov/books/NBK1218/
4. Hall P, Minnich S, Teigen C, Raymond K. Diagnosing lysosomal storage disorders: the GM2 gangliosidoses. Curr Protoc Hum Genet. 2014;83:17.16.1-8. doi:10.1002/0471142905.hg1716s83
5. Leal AF, Benincore-Florez E, Solano-Galarza D, et al. GM2 Gangliosidoses: Clinical Features, Pathophysiological Aspects, and Current Therapies. Int J Mol Sci. 2020;21(17):6213. Published 2020 Aug 27. doi:10.3390/ijms21176213
Report Available
2 to 6 daysMethod Name
Heat Inactivation, Fluorometric, Automated
Testing Algorithm
For more information see Tay-Sachs and Related Disorders Diagnostic Testing Algorithm
Forms
1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available:
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing-Spanish (T826)
2. Biochemical Genetics Patient Information (T602)
3. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.