Abstract
Most lysosomal storage diseases can be diagnosed by measuring the activity of a specific enzyme in an easily obtainable tissue sample. This can open the way to carrier identification in family members and prenatal testing when requested. A number of children and young adults with mental retardation, seizures and other clinical findings but normal enzyme values have been diagnosed as having a defect in sphingolipid catabolism by new techniques. Two additional types of patients with GM2 gangliosidosis have been identified. One type has a defect in hexosaminidase A (Hex A) not detectable with the usual fluorogenic substrate. The use of a sulfated synthetic substrate in the assay can make the diagnosis. Patients with a second variant type of GM2 gangliosidosis have normal Hex A levels but appear to be missing a required heat stable activator protein. Patients suspected of having GM2 gangliosidosis despite normal Hex A activity can be diagnosed by examining 1 ml of cerebrospinal fluid for gangliosides. Patients with normal arylsulfatase A activity have been demonstrated to excrete sulfatides and be unable to degrade 14C-sulfatide presented to their cultured cells. Their deficiency in a required sphingolipid activator protein (SAP-1) has been demonstrated using monospecific antibodies (Ab) in easily obtained tissue samples. When cultured cells from these patients were given 35S-methionine, and after 24 hrs they were lysed and treated with Ab, very little SAP-1 was produced.
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Wenger, D., Kudoh, T., Inui, K. et al. 1715 NEW METHODS FOR THE DIAGNOSIS OF VARIANT FORMS OF NEOROLIPIDOSIS. Pediatr Res 19, 396 (1985). https://doi.org/10.1203/00006450-198504000-01733
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DOI: https://doi.org/10.1203/00006450-198504000-01733