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Test ID NAGW Hexosaminidase A and Total Hexosaminidase, Leukocytes

Useful For

Carrier detection and diagnosis of Tay-Sachs disease

 

Carrier detection and diagnosis of Sandhoff disease

Method Name

Heat Inactivation, Fluorometric, Semi-Automated

Reporting Name

Hexosaminidase A and Total, WBC

Specimen Type

Whole Blood ACD


Ordering 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):

-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.



Shipping Instructions


For optimal isolation of leukocytes, it is recommended the specimen arrive refrigerated within 6 days of collection to be stabilized. Collect specimen Monday through Thursday only and not the day before a holiday. Specimen should be collected and packaged as close to shipping time as possible.



Specimen Required


Container/Tube:

Preferred: Yellow top (ACD solution B)

Acceptable: Yellow top (ACD solution A)

Specimen Volume: 6 mL

Collection Instructions: Send specimen in original tube. Do not aliquot.


Specimen Minimum Volume

5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood ACD Refrigerated (preferred) 6 days YELLOW TOP/ACD
  Ambient  6 days YELLOW TOP/ACD

Reference Values

HEXOSAMINIDASE TOTAL

≤15 years: ≥20 nmol/min/mg

≥16 years: 16.4-36.2 nmol/min/mg

 

HEXOSAMINIDASE PERCENT A

≤15 years: 20-80% of total

≥16 years: 63-75% of total

Day(s) Performed

Preanalytical processing: Monday through Saturday

Assay performed: Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

83080 x 2

LOINC Code Information

Test ID Test Order Name Order LOINC Value
NAGW Hexosaminidase A and Total, WBC 87544-3

 

Result ID Test Result Name Result LOINC Value
8775 Hexosaminidase Total, WBC 24075-4
2294 Hexosaminidase Percent A, WBC 23825-3
2284 Interpretation (NAGW) 59462-2
35029 Reviewed By 18771-6

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

Report Available

4 to 8 days

NY State Approved

Yes

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 in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Biochemical Genetics Patient Information (T602) in Special Instructions

3. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.