A new hereditary bone dysplasia with characteristic bowing and thickening of the distal ulna.

An autosomal dominant hereditary bone dysplasia was observed in three members of a Sardinian family living in Germany--the father and two sons. The guiding clinical symptom is thickening of the wrist proximal to the styloid process of the ulna. The radiologically recognizable changes--non-calcified cartilaginous islands protruding like cones into the metaphysis--begin with the onset of puberty and are not always associated with pain. Varying degrees of thickening and bowing of the relatively poorly mineralized metaphyseal region, particularly of the distal ulna, occur at the end of skeletal development. Thickening of the dorsum sellae is also characteristic. Serum calcium levels remain slightly elevated throughout life. The metatarsals, metacarpals and the distal fibula are dysplastic to varying degrees. The two boys display a coxa valga. Skeletal development is retarded. A developmental disorder of the vertebral column may form part of the condition, which defied allocation to any of the acknowledged forms of skeletal disease.