Pompe's disease: diagnosis in kidney and leucocytes using 4-methylumbelliferyl-alpha-D-glucopyranoside.

The diagnosis of Pompe's disease by the assay of acid alpha-glucosidase in kidney and leucocytes was not previously possible because of the presence of another component which had activity at pH 4.0, but was not deficient in the disease. This problem was resolved either by the use of the inhibitors, turanose, maltose and citrate, or by isoelectric precipitation at pH 5.0, which enabled the estimation of acid alpha glucosidase in kidney and leucocytes.