Biochemical genetics of the Lapland dog model of glycogen storage disease type II (acid α-glucosidase deficiency)

Abstract

A recently described canine model (Lapland dog) of glycogen storage disease type II (GSD II, Pompe disease, acid α‐glucosidase deficiency) was identified with several biochemical genetic methods. Complementation studies in which fibroblasts from a GSD II dog were fused with fibroblasts derived from control dogs and from human patients with different clinical forms of the disease did not lead to restoration of acid α‐glucosidase activity in the heterokaryon cell populations. These results indicate that acid α‐glucosidase deficiency is the primary defect in canine GSD II and that there is a close genetic parallelism with human GSD II. Immunotitration analysis of the residual acid α‐glucosidase activity in the canine GSD II fibroblasts and liver demonstrated that this residual activity was not due to acid α‐glucosidase enzyme, in which respect canine GSD II was similar to the infantile form of the human disease. Double immunodiffusion studies showed the presence of catalytically inactive acid α‐glucosidase enzyme protein in canine GSD II. This is consistent with a structural gene mutation. It is concluded that canine GSD II in the Lapland dog is a homologous model of the infantile form of human GSD II, a conclusion in concordance with clinical and pathological studies.