Hereditary distal myopathy with onset in infancy.

Abstract

SINCE GOWERS'¹description of distal myopathy in 1902, the specific aspects of this disorder have remained the subject of controversy. Some investigators suggest that a majority of patients with distal myopathy have atypical forms of myotonic dystrophy, Charcot-Marie-Tooth, or motor neuron disease. An important advance in the understanding of this problem was made in 1951 when Welander²clearly proved the existence of a distal myopathy, which she called "distal late hereditary myopathy." The clinical characteristics of this disorder include dominant inheritance, onset between the ages of 20 and 77 years of age (mean 47 years) with similar features in men and women, and slow progression. The disease begins with paresis and atrophy of the extensor and small muscles of the distal portion of the extremities. In most patients, weakness seems to start in the hands, causing clumsiness in performing fine movements. Electromyograms and muscle biopsies confirm