Gender dysphoria associated with disorders of sex development.

Disorders of sex development (DSDs) are estimated to be prevalent in 0.1-2% of the global population, although these figures are unlikely to adequately represent non-white patients as they are largely based on studies performed in Europe and the USA. Possible causes of DSDs include disruptions to gene expression and regulation-processes that are considered essential for the development of testes and ovaries in the embryo. Gender dysphoria generally affects between 8.5-20% of individuals with DSDs, depending on the type of DSD. Patients with simple virilizing congenital adrenal hyperplasia (CAH), as well as those with CAH and severe virilization, are less likely to have psychosexual disorders than patients with other types of DSD. Early surgery seems to be a safe option for most of these patients. Male sex assignment is an appropriate alternative in patients with Prader IV or V DSDs. Patients with 5α-reductase 2 (5α-RD2) and 17β-hydroxysteroid dehydrogenase 3 (17β-HSD3) deficiencies exhibit the highest rates of gender dysphoria (incidence of up to 63%). Disorders such as ovotesticular DSD and mixed gonadal dysgenesis are relatively rare and it can be difficult to conclusively evaluate patients with these conditions. For all DSDs, it is important that investigators and authors conform to the same nomenclature and definitions to ensure that data can be reliably analysed.