Diagnosis of alpha-mannosidosis by measuring alpha-mannosidase in plasma.
alpha-Mannosidosis is a lysosomal storage disease resulting from a deficiency of lysosomal alpha-mannosidase activity. Diagnosis of alpha-mannosidosis has traditionally been accomplished by demonstrating reduced alpha-mannosidase activity in leukocytes. We describe a new assay of alpha-mannosidase in serum or plasma that allows specific detection of the enzyme deficiency in alpha-mannosidosis with small, easily obtained sample volumes. The assay utilizes 40 microL of serum or plasma and a fluorescent substrate, 4-methylumbelliferyl-alpha-D-mannopyranoside in sodium acetate buffer, pH 4.0. The mean activity of a control population was 194 (SD 67) mU/L, whereas the activities obtained for four alpha-mannosidosis patients were 0, 17, 17, and 33 mU/L. Comparison with the standard leukocyte alpha-mannosidase assay showed this serum or plasma assay to be equally effective in diagnosing alpha-mannosidosis.
Prence
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EM
Division of Medical Genetics, Eunice Kennedy Shriver Center for Mental Retardation, Waltham, MA 02254.
Natowicz
M R
MR
D006801:Humans; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000097:blood*; D008247:Lysosomes / Q000201:enzymology; D008361:Mannosidases / Q000097:blood*; D012016:Reference Values; D043323:alpha-Mannosidase; D008363:alpha-Mannosidosis / Q000201:enzymology*
D007527:Isoenzymes; D008361:Mannosidases; D043323:alpha-Mannosidase