title: Clinical, Biochemical, and Genetic Characterization of Glycogen Storage Type IX in a Child with Asymptomatic Hepatomegaly.
abstract: Glycogen storage disease type IX (GSD IX) is caused by a defect in phosphorylase b kinase (PhK) that results from mutations in the PHKA2, PHKB, and PHKG2 genes. Patients usually manifest recurrent ketotic hypoglycemia with growth delay, but some may present simple hepatomegaly. Although GSD IX is one of the most common causes of GSDs, its biochemical and genetic diagnosis has been problematic due to its rarity, phenotypic overlap with other types of GSDs, and genetic heterogeneities. In our report, a 22-month-old boy with GSD IX is described. No other manifestations were evident except for hepatomegaly. His growth and development also have been proceeding normally. Diagnosed was made by histologic examination, an enzyme assay, and genetic testing with known c.3210_3212del (p.Arg1070del) mutation in PHKA2 gene.
authors.affiliation: Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jung Ah
authors.initials: JA
authors.lastname: Kim
authors.affiliation: Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Ja Hye
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Beom Hee
authors.initials: BH
authors.lastname: Lee
authors.affiliation: Medical Genetics Center, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Gu-Hwan
authors.initials: GH
authors.lastname: Kim
authors.affiliation: University Children's Hospital and Molecular Genetics and Metabolism Laboratory, Munich, Germany.
authors.forename: Yoon S
authors.initials: YS
authors.lastname: Shin
authors.affiliation: Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Han-Wook
authors.initials: HW
authors.lastname: Yoo
authors.affiliation: Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Kyung Mo
authors.initials: KM
authors.lastname: Kim
keywords: Glycogen storage disease; Glycogen storage disease type IX; Hepatomegaly; Phosphorylase b kinase 2; Phosphorylase kinase