A distinct phenotype of distal myopathy in a large Finnish family

OBJECTIVES: The authors carried out clinical, histopathologic, immunocytochemical, electrophysiologic, and imaging investigations and molecular genetic analysis in seven patients with distal myopathy belonging to a Finnish family. RESULTS: The disease showed autosomal dominant inheritance. Age at onset ranged from 32 to 45 years. The first symptoms for referral were clumsiness with the hands and frequent stumbling from a steppage gait. Muscle weakness was characterized by early involvement of the small muscles of the hands, gluteus medium, and both anterior and posterior muscle compartments of the legs. The disease progressed to involve other intrinsic muscles of the hands, as well as the forearm muscles, triceps and infraspinatus, and proximal lower limbs. Asymmetry of muscle involvement was common. EMG showed myopathic features, serum CK was normal or slightly elevated, and muscle biopsy showed many rimmed vacuoles and dystrophic changes. There was no evidence of linkage to Welander distal myopathy or tibial muscular dystrophy loci. CONCLUSION: These patients may have a distinct distal myopathy. Genome-wide scan is undertaken in order to identify the disease locus.