A liver PhK deficiency caused by variants in the PHKG2 gene. The disease is glycogen storage disease IXc (MONDO_0013091, a Monarch Disease Ontology entry). Also known as: GSD type 9C, GSD type IXc, GSD9C, PHKG2 glycogen storage disease, PHKG2-related glycogen storage disease type IX, glycogen storage disease caused by mutation in PHKG2, glycogen storage disease type IXc.