RESUMEN
Glycogen storage disease II [GSDII or Pompe disease, OMIM # 232300] is an autosomal recessive hereditary lysosomal disorder. Mutations in the GAA gene usually lead to reduced acid alpha-glucosidase [acid maltase, GAA, OMIM [asterisk] 606800, EC 3.1.26.2] activity, which results in impaired degradation and subsequent accumulation of glycogen within lysosomes. We present an Iranian boy, who was diagnosed with GSDII based upon clinical and biochemical findings. A single adenine insertion [insA] was detected at codon 693 that leads to a predicted premature stop codon at codon 736 in the GAA gene. The parents were heterozygous for the same change. According to the human genome mutation database [www.hgmd.org] and lecture reviews, the detected change is a novel mutation. We suppose that the discovered insertion in the GAA gene might lead to a reduced activity of the gene product. This assumption is in agreement with biochemical and clinical signs in the patient