Glycogen storage diseases of muscle.
Ten specific enzyme defects of glycogen metabolism affect skeletal muscle alone or in combination with other tissues. The newest addition to this group of disorders is the defect of aldolase A (glycogenosis type XII), a block in terminal glycolysis associated with myopathy and a hemolytic trait. The muscle glycogenoses cause two major syndromes, one characterized by exercise intolerance, cramps, and myoglobinuria, and the other dominated by fixed, often progressive weakness. This review considers sequentially recent advances in the following: clinical features or clinical variants, including a brief description of glycogenosis type XII; animal models, both spontaneous and genetically engineered; physiopathologic mechanisms, especially of the exercise intolerance and myoglobinuria; biochemical and molecular features--molecular defects are just beginning to be discovered for some glycogenoses (e.g. phosphorylase-b-kinase deficiency or branching enzyme deficiency), whereas they form long lists for others, such as acid maltase deficiency and myophosphorylase deficiency; and therapeutic approaches, including enzyme replacement and gene therapy.
DiMauro
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S
H. Houston Merritt Clinical Research Center for Muscular Dystrophy and Related Diseases, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Bruno
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C
D000818:Animals; D004195:Disease Models, Animal; D015316:Genetic Therapy; D006008:Glycogen Storage Disease / Q000201:enzymology* / Q000235:genetics / Q000628:therapy; D006801:Humans; D009132:Muscles / Q000201:enzymology* / Q000473:pathology