metabolic myopathies

metabolic myopathies are genetically inherited disorders of muscle energy production that result in skeletal muscle dysfunction. they are a large group of diseases with diverse inborn errors of metabolism, in particular muscle energy production, and including disorders of glycogen (lysosomal and non-lysosomal glycogenoses), lipid (disorders of fatty acid b-oxidation, primary carnitine deficiency, carnitine palmitoyltransferase deficiency, very long chain acyl-coa dehydrogenase deficiency, mitochondrial trifunctional protein deficiency, medium chain acyl-coa dehydrogenase deficiency, multiple acyl-coa dehydrogenase deficiency, coenzyme q10 deficiency) and mitochondrial metabolism. symptoms are often intermittent and provoked by exercise or changes in supply of lipid and carbohydrate fuels. cardiac and systemic metabolic dysfunction may coexist in the same patient. evaluation often requires provocative exercise testing. these tests may include ischemic forearm exercise, aerobic cycle exercise, and magnetic resonance spectroscopy with exercise. despite major advances in understanding their molecular mechanisms and the identification of causative genes, treatment of these diseases remains inadequate or lacking. this presentation will focus on two treatable metabolic myopathies namely pompe’s disease (glycogen storage type ii) and riboflavin-responsive multiple acyl-coa dehydrogenase deficiency (glutaric aciduria type ii).