LOW LEUKOCYTE PHOSPHORYLASE IN HEPATIC PHOSPHORYLASE-DEFICIENT GLYCOGEN STORAGE DISEASE

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Abstract
In view of the desirability of establishing the nature of the enzymatic defect in glycogen storage disease (GSD) without resorting to liver biopsy, methods were devised to measure WBC phosphorylase and glucose-6-phosphatase (G-6-Pase) in patients with this disease, their relatives and control subjects. Phosphorylase and G-6-Pase levels were determined by measuring inorganic phosphorus liberated from glucose-1-phosphate and glucose-6-phosphate respectively on sonicated WBC obtained by fibrinogen sedimentation. Two brothers with hepatic phosphorylase deficient GSD, proven by liver biopsy, had low WBC phosphorylase (5.5 and 7.1 [mu]gm P/107WBC) while this was normal in the father and an unaffected brother. The mother had a leucocyte phosphorylase level (10.2 [mu]gm P) midway between the lower limit of normal and the level in her 2 sons. The mean leucocyte phosphorylase level in 20 control subjects, was 29.6 [plus or minus] 1.2 ugm P/107WBC. G-6-Pase activity was not detectable in WBC. A patient with GSD clinically of G-6-Pase deficient type had a normal WBC phosphorylase. In vitro addition of glucagon stimulated phosphorylase in normal WBC 20% but adenylic acid had no significant effect. It is suggested that this method may be used as a diagnostic test for hepatic phosphorylase deficient GSD, and may be useful in determining the heterozygate state in this condition.