hymecromone and Lipidoses

We report a new assay for the detection of individuals heterozygous and homozygous for Gaucher's disease which requires relatively small samples of whole blood (0.3 ml), and which determines 4-methylumbelliferyl-beta-D-glucopyranoside:beta-glucosidase activity under conditions optimal for the determination of leukocyte glucocerebroside:beta-glucocereborsidase activity. The procedure involves the preparation of a leukocyte pellet from 50 mul of whole blood by hypotonic lysis of erythrocytes, followed by assay of beta-glucosidase activity at pH 5.5 in the presence of sodium taurocholate (0.6 g/100 ml). The methods described may also prove to be useful for the diagnosis of other diseases of enzyme deficiency which use fluorogenic substrates and leukocytes as a source of enzyme, such as Fabry's disease, Tay-Sachs disease, and generalized gangliosidosis.

Topics: Diagnosis, Differential; Fabry Disease; Gangliosides; Gaucher Disease; Glucosidases; Humans; Hymecromone; Leukocytes; Lipid Metabolism, Inborn Errors; Lipidoses; Methods; Microchemistry; Taurocholic Acid

In the course of screening for heterozygotes for beta-hexosaminidase deficiency, the serum and white cells of a clinically normal father of deficient children were found to have an apparent deficiency for both hexosaminidases A and B, assayed with an artificial substrate, 4-methylumbelliferyl-beta-glucosaminide. No inhibitor was present. Assayed with a natural substrate, n-acetylgalactosaminyl beta 1-4 galactosyl beta 1-4 glucosyl ceramide, which had been isolated from the brain of a patient with Tay--Sachs disease and labeled in the terminal n-acetyl-galactosamine, a value in the heterozygote range was found. It was concluded that the proband is probably a double heterozygote for two mutations; one is the classic Sandhoff type (lack of hexosaminidases A and B), giving rise to deficient offspring when combined with the same mutation borne by the wife. The other obscures any activity with the artificial substrate but allows an action on natural substrates, explaining the normal life of its carrier.

Topics: Aminoglycosides; Brain Chemistry; Child; Coumarins; Electrophoresis; Female; Gangliosides; Glucosamine; Heterozygote; Hexosaminidases; Hot Temperature; Humans; Hymecromone; Infant; Leukocytes; Lipidoses; Male; Mutation; Tritium