Pediatr Gastroenterol Hepatol Nutr.  2015 Jun;18(2):138-143. 10.5223/pghn.2015.18.2.138.

Clinical, Biochemical, and Genetic Characterization of Glycogen Storage Type IX in a Child with Asymptomatic Hepatomegaly

• Kim JA
• Kim JH
• Lee BH
• Kim GH
• Shin YS
• Yoo HW
• Kim KM

• KMID: 2315562
• DOI: http://doi.org/10.5223/pghn.2015.18.2.138

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.

Keyword

Glycogen storage disease; Glycogen storage disease type IX; Phosphorylase b kinase 2; Phosphorylase kinase; Hepatomegaly

MeSH Terms

Child*
Diagnosis
Enzyme Assays
Genetic Heterogeneity
Genetic Testing
Glycogen Storage Disease
Glycogen*
Growth and Development
Hepatomegaly*
Humans
Hypoglycemia
Infant
Male
Phosphorylase Kinase
Glycogen
Phosphorylase Kinase

Figure

• 

  Fig. 1 Pathologic findings. (A) Hepatocytes were filled with abundant glycogen particles in the cytoplasmonroutine transmission electron microscopy (×200). (B) Hepatocyte cytoplasmic material was positive byperiodic acid-Schiff staining (×200). (C) Hepatocyte cytoplasmic material was digested by diastase-treatment (×200).

• 

  Fig. 2 Partial genomic sequences of the PHAK2 gene. (A) The patient is a homozygotefor the c.3210_3212del (p.Arg1070del) mutation. (B) His mother is a heterozygote for this mutation.

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