New approaches for the treatment of metabolic myopathies

Metabolic myopathies are inborn errors of intermediate muscle metabolism, presenting either by exercise intolerance, or by progressive muscle weakness. Growing knowledge concerning the pathophysiology of these rare disorders, and the development of new technologies, opens new avenues for the treatment of this group of myopathies. Recent studies showed improvement in exercise capacity after regular aerobic exercise training in patients with McArdle's disease and mitochondrial myopathies. In late-onset Pompe disease enzyme replacement therapy trials with recombinant acid alpha-glucosidase (Myozyme) are currently in progress, the first trials conducted in childhood onset Pompe disease having previously shown a clear improvement in life expectancy and cardiac function. The demonstration that fibrates can induce correction of carnitine palmitoyl-transferase II deficiency in patients cells, lead to the development of an open-labelled therapeutic trial with bezafibrate in patients with CPTII deficiency, which is actually ongoing.