Glycogen storage disease type III (GSD III, OMIM 232400) is a rare autosomal recessive metabolic disease due to liver amylo‐1,6‐glucosidase (EC 3.2.1.33) deficiency (subtype IIIb), or liver and muscle deficiency (subtype IIIa) resulting from mutations in the AGL gene (1p21).1 The gene discussed is AGL; the disease is glycogen storage disease III.