Autosomal dominant and sporadic radio-ulnar synostosis.

We report on seven cases of congenital radio-ulnar synostosis (RUS). Five were found in the same family and two were sporadic. In six the synostosis was bilateral and consistently involved the proximal end of the radius and ulna. In the familial cases the anomaly was inherited as an autosomal dominant trait and was associated with a Dubois sign and relative shortness of metacarpals number 4 and 5 in two patients, and of number 2 in another patient, and of all phalanges of the 5th fingers. These observations suggest involvement of an ulnar developmental field. RUS does not seem to be rare in the Sicilian population.