A disorder of glycogen metabolism caused by a deficiency in liver and muscle phosphorylase kinase subunit b, is autosomal recessive and can lead to hepatomegaly, hypoglycemia after prolonged fasting, and growth retardation. The disease is Monarch Disease Ontology term MONDO_0009868 (glycogen storage disease IXb). Also known as: GSD IXb, GSD due to liver and muscle phosphorylase kinase deficiency, GSD type 9B, GSD type IXb, GSD9B, PHKB glycogen storage disease, PHKB-related glycogen storage disease type IX, glycogen storage disease 9B.