Studies in glycogen storage disease: III. Limit dextrinosis: A genetic study

Abstract

A case of type III glycogen storage disease is reported in which amylo-1,-6-glucosidaseactivity was markedly reduced in liver and muscle. The leukocyte debranching enzyme activity was higher than that observed in previous cases and was more in the range thought to be characteristic of heterozygotes. Although both parents had some reduction in the activity of leukocyte debranching enzyme, their muscle enzyme activity was normal. The father's hepatic amylo-1,6-glucosidase activity was normal, while the mother's was probably reduced. These results indicate tissue variability in the expression of both the homozygotic state in the patient and the heterozygotic state in the parents. The reasons for such findings are not apparent. Both the maternal and paternal grandfathers had significant reduction of amylo-1,-6-glucosidase activity consistent with the heterozygous state, while both grandmothers had normal enzyme levels. These results and those of leukocyte debranching enzyme assays in eight other relatives would be most consistent with a simple Mendelian recessive mode of inheritance of this type of glycogen storage disease in this patient.