Background Paper on Storage Disease

Glycogen storage disease (GSD) is the result of defects in the processing of glycogen synthesis or breakdown within muscles, , and other cell types. GSD in humans it is genetic caused by any inborn error of metabolism (genetically defective ) involved in these processes. In livestock, acquired GSD can be caused by ingestion of toxic alkaloids.

There are eleven (11) distinct diseases that are commonly considered to be glycogen storage diseases (some previously thought to be distinct have been reclassified). (Although 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: In the past, considered a distinct condition, now classified with VI. Has been described as X-linked recessive.

GSD type X: In the past, considered a distinct condition, now classified with VI.

Enzyme Hypo- Hepato- Hyperlip- Muscle Development/ Number Eponym Incidence Other symptoms deficiency glycemia? megaly? idemia? symptoms prognosis -6- von Gierke's 1 in 50,000- , GSD type I phosphatas Yes Yes Yes None Growth failure disease 100,000 births e *Death by age ~2 acid alpha- Pompe's 1 in 40,000 Muscle GSD type II No Yes No years (infantile glucosidase disease births weakness variant) Cori's glycogen disease or 1 in 100,000 GSD type III debranchin Yes Yes Yes Forbes' births g disease glycogen Yes, , Andersen GSD type IV branching No also No None death at age ~5 disease enzyme years muscle Exercise- Renal failure by glycogen McArdle induced , GSD type V 1 in 100,000[12] No No No phosphoryl disease , second wind ase Rhabdomyolys phenomenon

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is liver 1 in 65,000- glycogen Hers' GSD type VI 85,000 Yes Yes Yes [14] None phosphoryl disease births[13] ase Exercise- muscle induced Tarui's Haemolytic GSD type VII phosphofru No No No muscle Growth retardation disease anaemia ctokinase cramps and weakness phosphoryl Delayed motor GSD type IX ase kinase, - Yes Yes Yes None development, PHKA2 Growth retardation glucose Fanconi- GSD type XI transporter, Bickel Yes Yes No None GLUT2 syndrome Red cell Exercise GSD type XII aldolase ? ? ? intolerance, deficiency cramps Serum CK: Exercise Increasing intensity GSD type Episodic elevations; β- - ? ? ? intolerance, of over XIII Reduced with rest cramps decades [15] [15] Occasional glycogen Growth failure in GSD type 0 - Yes No No muscle synthase some cases cramping

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