Pure mitochondrial myopathy (Q106079)

Group of disorders characterized by sub-sarcolemmal accumulation of abnormal mitochondria and ragged red fibers which appear on Gomori trichrome stain Accumulation causes a defect in oxidative phosphorylation affecting the skeletal muscle. May present with proximal weakness, exercise intolerance, exertional dyspnea, lactic acidosis, diffuse myalgias, and eye muscle anomalies. Mutations of position 3250 of the mitochondrial genome are associated with the pure mitochondrial myopathies and there is typically a family history of similar problems.