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Distal myopathies are a heterogeneous group of genetic disorders characterized clinically by progressive muscular weakness of upper and lower limbs (hands or feet). Nonaka myopathy and Miyoshi myopathy are transmitted in an autosomal dominant pattern, whereas Welander myopathy, Udd/Markesbery-Griggs myopathy, distal myopathy with vocal cord and pharyngeal weakness and Laing myopathy are inherited as autosomal recessive traits. Miyoshi myopathy is associated with a striking elevated serum creatine kinase level and the typical findings of muscular dystrophy, whereas most of the distal myopathies have normal or mildly elevated creatine kinase levels and share the common pathologic feature of rimmed vacuoles. Advances in molecular genetics (identification of mutations in the causative genes dysferlin (Miyoshi type), GNE (Nonaka type) and TTN (Udd/Markesbery-Griggs myopathy)) will probably lead to changes in the classification of distal myopathies. |