Principle Of Method: Hydrolysis of the synthetic substrate 4-methylumbelliferyl-a-D-glucuronide at acid pH is followed by measuring the fluorescence of the liberated 4-methylumbelliferone after stopping the reaction with alkaline buffer.
Uses And Limitations Of The Method: Deficiency of b-glucuronidase is the primary defect in mucopolysaccharidosis (MPS) type VII (Sly disease). Since the mucopolysacchariduria is variable in MPS VII, assay of a-glucuronidase directly is recommended by the SAS laboratory for the diagnosis, rather than measurement of urinary glycosaminoglycan excretion. Serum or plasma are most conveniently used for the assay. The assay allows for prenatal diagnosis of MPS VII by use of chorionic villi or amniotic cells. The laboratory has very limited experience with carrier detection.
The assay is included in all our lysosomal enzyme screening procedures.
Specimen Requirements: Blood. 5 ml lithium heparin (orange capped tube) unseparated and unfrozen. Send at room temperature to arrive at the laboratory within 24h of venepuncture.
THE LABORATORY RECOMMENDS USE OF A COURIER SERVICE OR ROYAL MAIL SPECIAL DELIVERY FOR SENDING ALL SPECIMENS TO THE LABORATORY.