Nemaline myopathy is a congenital myopathy whose hallmark is the histopathological feature of “rods” or “nemaline” bodies accumulated at the periphery of most fibers that, on electron microscopy, are formed by protein crystalline structures that derive from several constituents of sarcomeric Z-line, such as alpha-actinin, tropomyosin, nebulin, and actin. The disease is therefore genetically heterogeneous, since many genes and proteins are responsible of different forms. The first gene identified in families with autosomal dominant nemaline myopathy was TPM3, encoding for alpha-tropomyosin-3 [1, 2]. Mutations in the same TPM3 gene may also originate different forms of congenital myopathies: “cap disease” [3, 4] which is characterized histopathologically by peculiar cap-like inclusions at the periphery of muscle fibers and congenital fiber-type disproportion [5, 6] which is characterized by hypotrophy of type 1 muscle fibers. Recessive mutations in TPM3 gene may also cause nemaline myopathy , and it was suggested that patients with recessive mutations may have more severe phenotype than those with dominant gene mutations [2, 7, 8].
Nemaline myopathy Alpha-tropomyosin-3
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