Summary
Proximal symphalangism or Cushing's symphalangism is characterised by fusion of the proximal interphalangeal joints. Other joints may also be affected, leading to ankylosis of the elbows, ankles and wrists (fusion of the carpal and tarsal bones). Conductive deafness due to fusion of the ossicles is also a characteristic feature. The condition is transmitted as an autosomal dominant trait and the causative gene has been identified as NOD and localised to chromosome 17q22. *Author: Orphanet (March 2006)*.
