Benign autosomal dominant myopathy
Overview
Bethlem myopathy is an apparently rare early-onset benign autosomal dominant limb-girdle myopathy with contractures of the fingers. To determine whether this disorder is unrecognized rather than rare we used muscle computerized tomography (CT) and isokinetic muscle testing and assiduously sought contractures of the fingers in relatives of two patients with the disease.
Symptoms
* Progressive limb girdle weakness * Finger contractions * Elbow contractions * Ankle contractions * Reduced joint mobility
Causes
Muscular dystrophy is caused by various genetic mechanisms. Duchenne’s and Becker’s muscular dystrophies are X-linked recessive disorders. Both result from defects in the gene coding for the muscle protein dystrophin; the gene has been mapped to the Xp21 locus. The incidence muscular dystrophy is about 1 in 651,450 persons in the United States. Duchenne’s and Becker’s muscular dystrophies affect males almost exclusively.