Mondo Description Glycogen storage disease (GSD) due to liver and muscle phosphorylase kinase (PhK) deficiency is a benign inborn error of glycogen metabolism. It is the mildest form of GSD due to PhK deficiency.

Uniprot Description A metabolic disorder characterized by hepatomegaly, only slightly elevated transaminases and plasma lipids, clinical improvement with increasing age, and remarkably no clinical muscle involvement. Biochemical observations suggest that this mild phenotype is caused by an incomplete holoenzyme that lacks the beta subunit, but that may possess residual activity.