Syndactyly

Syndactyly is a condition in which two or more digits, fingers or toes, are fused together. The word comes from the Ancient Greek for together and finger. Webbing of this kind is normal in some marsupial mammals, but it is unusual in humans. It is classified as simple when adjacent digits are joined only by soft tissue and complex when the bones are fused, and as complete or incomplete depending on how far toward the tip the skin is joined. Complex forms tend to occur within syndromes such as Apert syndrome, while fenestrated or terminal forms are associated with amniotic band syndrome. Five genetic types have been mapped to distinct chromosomal loci. The atlas records it as a congenital difference of the hands and feet, described here as a classification of what is observed, not as guidance for any individual case.