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 enzyme assay, polymerase chain reaction (PCR)/primer extension for molecular assay.
Plasma Enzyme Assay Conventional Units | Plasma Enzyme Assay SI Units (Conventional Units × 0.0167) | ||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Hexosaminidase Total | 589–955 nmol/hr/mL | 9.83–15.98 nmol/hr/mL | |||||||||||||||||||||||||||||||||||||||
Hexosaminidase A | 55%–76% of total hexosaminidase | 55%–76% of total hexosaminidase | |||||||||||||||||||||||||||||||||||||||
Whole blood leukocyte assay: greater than 62% | Molecular assay: Negative for HEXA gene mutations | Molecular assay: Negative for HEXB variants | |||||||||||||||||||||||||||||||||||||||
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
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