We report on 2 brothers with a severe progressive disorder characterized by thick skin, acne conglobata, "coarse" face, osteolysis, gingival hypertrophy, brachydactyly, camptodactyly, and mitral valve prolapse. The youngest brother died at age 24 years because of heart failure. Biochemical and pathological studies excluded known metabolic diseases. We think that this is a new genetic disorder inherited in autosomal recessive or X-linked recessive manner.