Preferred test to evaluate symptomatic patients for Tay-Sachs disease or Sandhoff disease. Can identify carriers of Tay-Sachs disease. Can identify carriers of Sandhoff disease. For individuals who are pregnant, use oral contraceptives, have severe liver or autoimmune disease, or have a previous inconclusive HEX A enzyme serum/plasma test, the preferred test is Hexosaminidase A percent and Total Hexosaminidase in Leukocytes (2008125) to avoid false-positive results.
Yellow (ACD). Also acceptable: Plain red.
Do not transfer whole blood to other containers. Transport 3 mL whole blood (Min: 1 mL) or transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.2 mL)
Whole blood: Room temperature. Serum: Frozen
Clinical information is needed for appropriate interpretation. Additional required information includes age, gender, diet (e.g.TPN therapy), drug therapy, and family history. Biochemical Genetics Patient History Form is available on the ARUP Web site at https://www.aruplab.com/patienthistory or by contacting ARUP Client Services.
Whole blood: Ambient: 3 days; Refrigerated: 3 days; Frozen: Unacceptable
Serum: Ambient: 3 days; Refrigerated: 7 days; Frozen: 1 month
|No||Hexosaminidase A Percent||55-76 percent|
|No||Hexosaminidase Total||Effective August 17, 2015
600-1050 nmol hydrolyzed/hr/mL
Refer to report.
Laboratory Developed Test (LDT)
This test is used for the diagnosis of Tay-Sachs disease and can also be used to identify carriers for this disorder. Carrier screening is offered to individuals of Ashkenazi Jewish descent because of the high incidence of the disease in this population. Pregnant women or women using oral contraceptives cannot be tested using plasma or serum because of high false-positives rates. In serum samples, false positives can also be caused by several other conditions, including severe liver disease and autoimmune diseases. Testing in leukocytes should be used in these cases.
|Component Test Code*||Component Chart Name||LOINC|
|2008123||Hexosaminidase A Percent||12914-8|
|2008124||Hexosaminidase Plasma/Serum Interp|
- Plasma and serum hexosaminidase Hexosaminidase A and Total, plasma or serum