Bilateral symphalangism of the index fingers.

True symphalangism is a rigid digit of normal length. Fusion at the proximal interphalangeal joint is most common, and the index finger is the least likely to be affected. I report the second instance of true symphalangism involving fusion of the distal interphalangeal joints of both index fingers without symphalangism of any other digits. This is the first case reported in a black and was inherited as a simple Mendelian dominant trait.