The distal myopathies are a clinically and pathologically heterogeneous group of genetic disorders in which the distal muscles of the upper or lower limbs are selectively or disproportionately affected. Although there is some uncertainty as to the actual diagnosis, the first case description of distal myopathy is usually attributed to Gowers in 1902.1 However, it was not until the landmark publication by Welander in 19512 describing a large cohort of patients with a dominantly transmitted late onset familial form of distal myopathy in Sweden, that this group of disorders became firmly established. Other dominant and recessive forms with distinctive clinical phenotypes and muscle pathology have since been recognised, particularly in Finland and Japan.3-6 Linkage to chromosome 14q11 was first reported in an Australian family with early onset autosomal dominant distal myopathy in 19957 and genetic linkage has since also been described in the other five major forms of distal myopathy8-11 (table 1). To date, the responsible gene has been identified in only one of these (Miyoshi myopathy), in which mutations have been found in the dysferlin gene at chromosome 2p12–14.13

Comparison of the different forms of distal myopathy has shown considerable phenotypic variability, both in terms of the age at which symptoms first develop and the pattern of differential involvement of the limb muscles and of other muscle groups such as those of the neck and face. Moreover, it has been recognised that similar phenotypes may result from different genetic defects and conversely, that certain defects such as the dysferlin gene mutations may be associated with different clinical phenotypes including one form of limb girdle muscular dystrophy (LGMD2B).12 13 At the histological level, several of the distal myopathies are characterised by the …