Disorders of sexual development.

Over the past 6 years, the structures of four key genes involved in sexual differentiation have been identified (see Figure 2). Mutations within these genes have been demonstrated to cause a significant percentage of the disorders of sexual differentiation described in this chapter. It should be noted, however, that there are significant numbers of patients with these disorders in whom no mutation in any of these genes has yet been characterized. It is probable that further genes involved in sexual differentiation will be identified and shown to be the cause of a number of these diseases.