Hexosaminidase Testing

General

Synonym/Acronym:
TSD (Tay-Sachs disease) testing.

Rationale
To assist in diagnosing Tay-Sachs and Sandhoff disease by identifying a hexosaminidase enzyme deficiency.

Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings
Method: Fluorometry for whole blood leukocyte assay, polymerase chain reaction (PCR)/primer extension for molecular assay.

Hexosaminidase Total (Whole Blood Leukocyte Assay)
Less than or equal to 15 yr Greater than or equal to 20 nmol/min/mg
16 yr–adult 16.4–36.2 nmol/min/mg
Hexosaminidase A (Whole Blood Leukocyte Assay)
Less than or equal to 15 yr 20%–80% of total hexosaminidase
16 yr–adult 63%–75% of total hexosaminidase
Molecular assay
Negative for HEXA gene sequence variations
Methods vary, reference ranges vary; the reference range and interpretive summary provided in the laboratory report should be used to properly evaluate results. Carrier values are approximately half of the expected normal values.

Critical Findings and Potential Interventions
N/A

There's more to see -- the rest of this topic is available only to subscribers.