Five members from 3 generations, including a 35-year-old woman and her 2 sons, both mentally impaired to a different degree, were studied in a tertiary care hospital. Anamnestic, clinical, neurological, and radiological evaluations were used to describe phenotypes. A and B postaxial polydactyly, transmitted likely as autosomal dominant, was associated with an extensive variability of phenotypic features: (1) cutaneous syndactyly, (2) nail-teeth dysplasia, (3) osteopenia, and (4) mental delay. The likelihood that the constellation of observations we report here is caused by mutation of a single gene that subsequently affects multiple physiological activities, although fascinating, remains to be proven. Instead, we hypothesize that it likely develops as a contiguous gene syndrome.