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
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