Myopathies resulting from mutations in sarcomeric proteins

PURPOSE OF REVIEW: The past decade has seen the discovery of the major role that mutations in the protein components of the sarcomere plays as a cause of human muscle disease. An overview of the more precise molecular definitions of these diseases is timely. RECENT FINDINGS: Recent findings include: the beginnings of an understanding of the role of the sarcomere in controlling muscle gene expression; the theoretical analysis of the increasing number of mutations identified in the skeletal muscle actin gene; the identification of mutations in myosin causing hereditary inclusion body myopathy and hyaline body myopathy and the identification of mutations in myotilin in myofibrillar myopathy. SUMMARY: An increasing spectrum of human muscle diseases is being shown to be caused by mutations in proteins of all the major components of the sarcomere. Molecular analysis is providing a more accurate delineation of these diseases, but for the giant nebulin and titin genes, molecular diagnosis remains difficult. Treatment options for these disorders will only come through a deeper understanding of the sarcomere and of the pathogenesis of its disorders.