Cenani-Lenz syndrome (CLS) is a congenital malformation syndrome that associates a complex syndactyly of the hands with malformations of the forearm bones and similar manifestations in the lower limbs.

Fusion involving two or more metacarpal bones (A synostosis of the first metacarpal and the proximal phalanx of the thumb can also be observed, note that the first metacarpal bone corresponds to a proximal phalanx).