Treatment Opportunities in Patients With Metabolic Myopathies.

Metabolic myopathies are disorders affecting utilization of carbohydrates or fat in the skeletal muscle. Adult patients with metabolic myopathies typically present with exercise-induced pain, contractures or stiffness, fatigue, and myoglobinuria. Symptoms are related to energy failure. Purpose of review In this review, the current treatment options, including exercise therapy, dietary treatment, pharmacological supplementation, gene transcription, and enzyme replacement therapy, are described. Recent findings Recognition of the metabolic block in the metabolic myopathies has started the development of new therapeutic options. Enzyme replacement therapy with rGAA has revolutionized treatment of early onset Pompe disease. Supplements of riboflavin, carnitine, and sucrose show promise in patients with respectively riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency, primary carnitine deficiency, and McArdle disease. Treatment with citric acid cycle intermediates supply by triheptanoin seems promising in patients with glucogenoses, and studies are ongoing in patients with McArdle disease. Summary Treatment of metabolic myopathies primarily relies on avoiding precipitating factors and dietary supplements that bypass the metabolic block. Only a few of the used supplements are validated, and further studies are needed to define efficacious treatments. Further potential treatment targets are molecular therapies aimed at enzyme correction, such as chaperone therapy, gene therapy, gene expression therapy, and enzyme replacement therapies.