Novel PHKG2 mutation causing GSD IX with prominent liver disease: report of three cases and review of literature.

Abstract

Glycogen storage disease type IX (GSD IX) is a common form of glycogenosis due to mutations in PHKA1, PHKA2, or PHKB and PHKG2 genes resulting in the deficiency of phosphorylase kinase. The first two genes are X-linked while the latter two follow an autosomal recessive inheritance. The majority of cases of GSD IX are attributed to defects in PHKA2 which usually cause a mild disease. We report three patients with PHKG2-related GSD IX presenting with significant hepatic involvement, fibrosis, and cirrhosis. Interestingly, the homozygosity mapping resolved a dilemma about an erroneously normal phosphorylase kinase activity in patient 1. The novel mutation found in all the three patients (p.G220E) affects the catalytic subunit of the phosphorylase kinase. Increasing evidence shows that patients with PHKG2 mutations have a severe hepatic phenotype within the heterogeneous GSD IX disorder. Therefore, defect in PHKG2 should be considered in patients with suspected glycogenosis associated with significant liver fibrosis and cirrhosis.

• Authors: Buthainah Albash, Faiqa Imtiaz, Hamad Al-Zaidan, Hadeel Al-Manea, Mohammed Banemai, R Allam, Ali Al-Suheel, Mohammed Al-Owain
• Journal: European journal of pediatrics (Eur J Pediatr) Vol. 173 Issue 5 Pg. 647-53 (May 2014) ISSN: 1432-1076 [Electronic] Germany
• PMID: 24326380 (Publication Type: Case Reports, Journal Article, Review)

Chemical References

• Phosphorylase Kinase

Topics

• Female
• Genotype
• Glycogen Storage Disease (genetics)
• Humans
• Infant
• Liver Diseases (genetics)
• Male
• Mutation
• Phenotype
• Phosphorylase Kinase (genetics)
• Polymerase Chain Reaction
• Saudi Arabia