Disorders or Differences of Sex Development

Disorders or Differences of sex development (DSD) refer to a diverse group of conditions in which chromosomal, gonadal, or anatomic sex development is atypical. DSDs may present at various ages, ranging from the prenatal period to adulthood. Many different health care professionals may be involved and diagnostic evaluation as well as long-term care is ideally provided by a multidisciplinary team. The field of DSD has rapidly changed in the last decades. As these conditions result from a broad spectrum of naturally occurring developmental variations and do not always need medical actions, many prefer to use the umbrella term “Differences” rather than “Disorders” of Sex Development. Indeed, many of the terms previously used are now considered potentially derogative and imprecise. DSDs can be classified based on karyotype with further subdivision in disorders of gonadal development and problems of hormone synthesis or action. This classification will be followed in this chapter. The increased availability of next generation sequencing has allowed for the identification of many new genes involved in DSD and the advent and increased accessibility of this technology has changed the diagnostic approach and refined the molecular genetic diagnosis in many cases. Societal changes have also had a major impact. The binary concept of gender is being interrogated. In parallel, questions have been raised about the necessity and the timing of interventions with more emphasis on the right of the affected individuals to be involved in decisions regarding treatment. Full disclosure is essential for people to be able to make informed decisions. In addition, support groups are increasingly involved in discussions about optimal care and in defining research priorities.