Congenital nemaline myopathy. II. Quantitative changes in alpha-actinin and myosin in skeletal muscle.

Skeletal muscle obtained from 2 patients with congenital nemaline myopathy (CNM) and from a healthy control was analyzed by 1- and 2-dimensional gel electrophoresis. In total extracts, an increase of alpha-actinin by a factor of 2:3 was found for CNM muscle as compared with the control. One- and two-dimensional gels revealed the presence of LCF3, the smallest light chain associated with type 2 (fast) myosin in total extracts of normal control of mixed fiber type. Both CNM samples showed the absence of this polypeptide. This result is consistent with the finding that muscle of the 2 patients exhibited nearly exclusively the ATPase activity indicative of type 1 (slow) myosin.