Human HOX gene mutations

HOX genes play a fundamental role in the development of the vertebrate cent ral nervous system, axial skeleton, limbs, gut, urogenital tract and extern al genitalia, but it is only in the last 4 years that mutations in two of t he 39 human HOX genes have been shown to cause congenital malformations: HO XD13, which is mutated in synpolydactyly, and HOXA13, which is mutated in H and-Foot-Genital syndrome. Here we review the mutations already identified in these two genes, consider how these mutations may act, and discuss the p ossibility that further mutations remain to be discovered both in developme ntal disorders and in cancer.