Early-onset benign autosomal dominant limb-girdle myopathy with contractures (Bethlem myopathy) in a Japanese family

We report a family showing an early-onset benign autosomal dominant limb-girdle myopathy with contractures. The clinical features in our family included; 1) slowly progressive limb-girdle muscle weakness since childhood. 2) contractures of fingers, elbows and ankles, 3) mild motor impairment with preserved activities of daily living. The disease was inherited through an autosomal dominant trait. Muscle pathology revealed variation in fiber size, slightly increased central nuclei, mild endomysial fibrosis, type 1 fiber predominance and type 2 fiber atrophy. The above clinical features were similar to those seen in patients reported by Bethlem (1976) and Mohire (1988), and therefore we made a diagnosis of Bethlem myopathy on this familial patients which was extremely rare in Japan.