Myopathies Due to Glycogen Metabolism Abnormalities
Myopathies due to glycogen metabolism abnormalities produce hepatomegaly and hypoglycemia (debrancher enzyme deficiency), hepatomegaly, large heart, prominent muscles, and large tongue (Pompe’s disease is also called alpha-glucosidase deficiency), or arthrogryposis (McArdle disease is also called muscle phosphoylase deficiency). Myopathies due to disorders of glycogen metabolism are recognized by the presence of PAS-positive subsarcolemmal vacuoles on muscle biopsy. Biochemical studies show absence of the specific enzyme.