A new familial, autosomal dominant, myopathy and variant of hereditary inclusion body myopathy (HIBM) is described in 19 members of a large Swedish family followed in the Departments of Pediatrics, Genetics, and Pathology, Sahlgrenska University Hospital, Goteborg, Sweden. Onset was in the newborn period with congenital joint contractures in 14, hip dislocation in 4, limb-girdle weakness and muscular atrophy, external ophthalmoplegia, and decreased tendon reflexes. The course was nonprogressive in childhood, and joint contractures resolved. From 30 to 50 years of age, most patients showed deterioration, with progressive muscle weakness and atrophy, especially of quadriceps. EMG showed myopathic changes, and serum CK was elevated. Muscle biopsy showed focal disorganization of myofilaments in childhood cases, and dystrophic changes in adults, with rimmed vacuoles and cytoplasmic and intranuclear inclusions. 
COMMENT. Inclusion body myopathies are sporadic and inflammatory or familial and hereditary. The above Swedish family appears to suffer from a unique form of autosomal dominant HIBM that presents at birth and shows a progressive deterioration in adult life.