myopathy

Any abnormal condition or disease of the muscular tissues; commonly designates a disorder involving skeletal muscle. [myo- + G. pathos, suffering]

- carcinomatous m. SYN: Lambert-Eaton syndrome.

- centronuclear m. slowly progressive generalized muscle weakness and atrophy beginning in childhood; on biopsy of skeletal muscle, the nuclei of most muscle fibers are seen to be located near the center of a small fiber (the normal position for a 10-week embryo) rather than at the periphery of the fiber; familial incidence. Autosomal dominant [MIM*160150] recessive [MIM*255200] and X-linked [310400] forms occur. The X-linked form is caused by mutation in the myotubular m. gene (MTM1) on Xq28. SYN: myotubular m..

- distal m. m. affecting predominantly the distal portions of the limbs; onset is usually after age 40, with weakness and wasting of small muscles of the hands; The infantile form [MIM*160300] and the Swedish later-onset [MIM*160500] are autosomal dominant. There is a Japanese late-onset type [MIM*254130] that is recessive and is caused by mutation in the gene encoding dysferlin on 2p13.

- dysthyroid m. SYN: thyrotoxic m..

- minicore-multicore m. an uncommon nonprogressive m. with early onset, proximal weakness, and hypotonia. Muscle fibers show focal defects of oxidative and myofibrillar adenosine triphosphatase enzymes with disorganization of myofibril ultrastructure.

- mitochondrial m. weakness and hypotonia of muscles, primarily those of the neck, shoulder, and pelvic girdles, with onset in infancy or childhood; on biopsy, giant, bizarre mitochondria are seen located between muscle fibrils just beneath the sarcolemma. There are autosomal dominant [MIM*251900] and recessive forms due to deletions or duplications of mitochondrial DNA, with one recessive form [MIM*252010] associated with a deficiency of complex 1 of the mitochondrial respiratory chain.

- myotubular m. SYN: centronuclear m..

- nemaline m. congenital, nonprogressive muscle weakness most evident in the proximal muscles; named after the characteristic nemaline (threadlike) rods seen in the muscle cells composed of Z-band material. There are two forms, dominant [MIM*161800] caused by mutation in the tropomyosin-3 gene (TPM3) on 1q22–q23, and recessive [MIM*256030], that are clinically indistinguishable. SYN: rod m..

- ocular m. SYN: chronic progressive external ophthalmoplegia.

- proximal myotonic m. (PROMM) an autosomal dominant, multisystem disorder, with onset in young adult life, characterized by proximal myotonia and weakness, muscle pain, baldness, cataracts, cardiac conduction disturbances, and testicular atrophy. In contrast to myotonic dystrophy, features of this disorder do not include facial weakness and ptosis, distal limb weakness and wasting, and trinucleotide repeat expansion at the gene loci for myotonic dystrophy.

- rod m. SYN: nemaline m..

- thyrotoxic m. extreme muscular weakness in severe thyrotoxicosis affecting muscles of limbs and trunk as well as those used in speech and swallowing. SYN: dysthyroid m..

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my·op·a·thy mī-'äp-ə-thē n, pl -thies a disorder of muscle tissue or muscles

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n.

any disease of the muscles. The myopathies are usually subdivided into those that are inherited (see muscular dystrophy) and those that are acquired. The acquired myopathies include polymyositis and muscular diseases complicating endocrine disorders or carcinoma. All are typified by weakness and wasting of the muscles, which may be associated with pain and tenderness.

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my·op·a·thy (mi-opґə-the) [myo- + -pathy] any disease of a muscle.