Clinical course correlates poorly with muscle pathology in nemaline myopathy

Very numerous nemaline bodies, glycogen accumulation, and marked sarcomeric disruption were common in nemaline myopathy associated with mutations in skeletal alpha-actin. Nemaline myopathy due to mutations in alpha-tropomyosin(SLOW) was characterized by preferential rod formation in, and atrophy of, type 1 fibers. Light microscopic features of nemaline myopathy correlate poorly with disease course. Electron microscopy may correlate better with disease severity and genotype.