Humeroradial synostosis and the multiple synostosis syndrome: case report.

Humeroradial synostosis may occur sporadically or as an extremely rare inheritable disorder. The current classification divides cases into class I (fixed in extension with ulnar ray hypoplasia) or class II (fixed in flexion without hypoplasia). Familial cases of class II synostosis segregate into autosomal recessive and autosomal dominant groups. Autosomal recessive pedigrees are heterogeneous. However, when inherited as an autosomal dominant some cases of humeroradial synostosis demonstrate striking similarities limited to the musculoskeletal system: class II humeroradial synostosis, proximal symphalangism, short first metacarpal and metatarsal bones, carpal and tarsal coalitions and a prominent nasal bridge. We believe that when class II humeroradial synostosis is associated with these features, the primary diagnosis is the multiple synostosis syndrome. Furthermore, a prominent nasal bridge is present in the neonate and may aid diagnosis at this stage. We illustrate these findings with the case of a mother and only child, both demonstrating class II humeroradial synostosis and features characteristic of the multiple synostosis syndrome.