Glycogen storage disease
Glycogen storage disease (GSD, also glycogenosis and dextrinosis) is the result of defects in the processing of glycogen synthesis or breakdown within muscles, liver, and other cell types. GSD has two classes of cause: genetic and acquired. Genetic GSD is caused by any inborn error of metabolism (genetically defective enzymes) involved in these processes. In livestock, acquired GSD is caused by intoxication with the alkaloid castanospermine.
TypesThere are eleven distinct diseases that are currently classified glycogen storage diseases (some previously thought to be have been reclassified, see remarks below): Remarks:
- Some GSDs have different forms, e.g. infantile, juvenile, adult (late-onset).
- Some GSDs have different subtypes, e.g. GSD1a / GSD1b, GSD9A1 / GSD9A2 / GSD9B / GSD9C / GSD9D.
- GSD type 0: Although glycogen synthase deficiency does not result in storage of extra glycogen in the liver, it is often classified with the GSDs as type 0 because it is another defect of glycogen storage and can cause similar problems.
- GSD type VIII (GSD 8): In the past it was considered a distinct condition, however it is now classified with GSD type VI or GSD IXa1;[https://www.omim.org/entry/306000
- GSD type X (GSD 10): In the past it was considered a distinct condition, however it is now classified with GSD VI (gene PGAM2).
- GSD type XI (GSD 11): Fanconi-Bickel syndrome, hepatorenal glycogenosis with renal Fanconi syndrome, no longer considered a glycogen storage disease.
- GSD type XIV (GSD 14): Now classed as Congenital disorder of glycosylation type 1 (CDG1T), affects the phosphoglucomutase enzyme (gene PGM1). Glycogen Metabolism themedicalbiochemistrypage.org