PHKG2 mutation spectrum in glycogen storage disease type IXc: a case report and review of the literature

Background: PHKG2 gene mutation can lead to liver phosphorylase kinase (PhK) deficiency, which is related to glycogen storage disease type IX (GSD IX). GSD IXc due to PHKG2 mutation is the second most common GSD IX. Methods: We identified a novel mutation (c.553C>T, p.Arg185X) in PHKG2 in a Chinese family and verified it by next-generation and Sanger sequencing. The mutation spectrum of the PHKG2 gene was summarized based on 25 GSD IXc patients with PHKG2 mutations. Results: We found that missense mutation (39%) was the most common type of mutation, followed by nonsense mutation (23%). Mutations were more prevalent in Asian (12/25) and European (9/25) populations than in populations from elsewhere. The exons had more sites of mutation than the introns, and exons 3 and 6 were the most frequent sites of mutations. Conclusions: This study expands our knowledge of the PHKG2 gene mutation spectrum, providing a molecular basis for GSD IXc.