Genetic principles of differences of sex development

There are manifold reasons for the occurrence of differences of sex development (DSD). They can become manifested during embryonal as well as fetal development. Numeric and structural variants of sex chromosomes as well as single genes involved during gonadal determination and differentiation (sex-specific development of internal and external genitalia) all play a role. In addition, disorders affecting steroidogenic hormone synthesis or steroid hormone receptors and maternal factors are involved in the development of DSD. This article reviews the most important DSD-associated genes of gonadal determination and differentiation and gives presents the DSD classification according to the Chicago consensus conference.