Nevoid basal cell carcinoma syndrome: molecular biology and new hypotheses.

To understand the molecular biology of the nevoid basal cell carcinoma syndrome, the hedgehog signaling network is explained. The syndrome is caused by mutations in patched, a tumor suppressor gene. A single point mutation in one patched allele may be responsible for the malformations found in the syndrome. Inactivation of both patched alleles results in the formation of tumors and cysts (basal cell carcinomas, odontogenic keratocysts, and medulloblastomas). Several new hypotheses are proposed to account for a minority of nevoid basal cell carcinoma syndrome patients. Evidence is provided to suggest that these hypotheses deserve to be investigated.