[Clinical characteristics and GAA gene mutation in children with glycogen storage disease type II: an analysis of 3 cases].

Glycogen storage disease type II (GSD II) is an autosomal recessive disorder caused by a deficiency of the lysosomal glycogen-hydrolyzing enzyme acid α-glucosidase (GAA) and can affect multiple systems including the heart and skeletal muscle. The aim of this study was to investigate three children with GSD II confirmed by GAA gene analysis and to report their clinical characteristics and gene mutations. One case was classified as infantile-onset GSD II, and two cases as late-onset GSD II. The infantile-onset patient (aged 4 months) showed no weight increase and had dyspnea, muscle hypotonia, and increased alanine aminotransferase and creatine kinase; echocardiography showed hypertrophic cardiomyopathy. The late-onset patients (aged 8 years and 13 years respectively) showed persistently elevated liver enzymes; one of them had recurrent respiratory tract infection and restrictive ventilation disorder, and the other case showed significantly increased creatase but normal electromyographic findings. Peripheral blood genetic testing for GAA gene showed six pathogenic mutations in the three cases, and the mutations c.2738C>T and c.568C>T had not been reported. Therefore, peripheral blood genetic testing for GAA gene is an effective diagnostic method.