Enhanced enzyme activity after incubation with zinc can be used to distinguish heterozygotes of Pompe's disease.

In an attempt to identify heterozygotes for Pompe's disease, the acid alpha-D-glucosidase activity at pH 4 in phytohemagglutinin-stimulated lymphocytes was measured. In the standard assay an overlap in the enzyme activity between normal controls and obligate heterozygotes was demonstrated. When the assay was modified by adding zinc chloride into the incubation mixture, the enzyme activity of the lymphocyte homogenates did not change. However, the enzyme activity increased dramatically after intact lymphocytes were preincubated with zinc chloride. There was no more overlap in the acid alpha-D-glucosidase activity between normal controls and obligate heterozygotes when lymphocytes were incubated 1 h with 10(-4) mol/liter zinc chloride or 2 h with 10(-3) or 10(-4) mol/liter zinc chloride. This modified enzyme activity should facilitate improved heterozygote detection.