Glycogen storage disease type 0 glycogen primer. Its action is highly regulated by a mechanism of phosphorylation and dephosphorylation and modulated by counter-regulatory hormones including insulin, epinephrine, and glucagon. Mutations in the gene for liver glycogen synthetase (GYS2, 138571) result in decreased or absent activity of liver glycogen synthetase and moderately decreased amounts of structurally normal glycogen in the liver. Mutational studies of patients with glycogen-storage disease type 0 do not demonstrate correlations between genotype and phenotype. [3] A different gene (GYS1, 138570) encodes muscle glycogen synthetase, which has normal activity in patients with glycogen-storage disease type 0A. In the early stages of fasting, the
Adult polyglucosan body disease Adult polyglucosan body disease Adult polyglucosan body disease (APBD) is an orphan disease and a glycogen storage disorder that is caused by an inborn error of metabolism. Symptoms can emerge any time after the age of 30; early symptoms include trouble controlling urination, trouble walking, and lack of sensation in the legs. People eventually develop dementia. A person inherits loss-of-function mutations in the "GBE1" gene from each parent, and the lack of glycogen branching enzyme (the protein encoded by "GNE1") leads to buildup of unbranched glycogen in cells, which harms neurons more than other kinds of cells. Most people first