Disorders of sex development (DSD) are relatively rare conditions with diverse pathophysiology, which usually present in the newborn or adolescent periods. These conditions are very heterogeneous and can present in a variety of different ways, most commonly with ambiguous genitalia noticed in the newborn period or delayed puberty in adolescents. The impact of these disorders on the lives of these patients and their families should not be underestimated. These clinical situations can often be difficult to manage, particularly in those cases where the sex of rearing is uncertain. The needs of each individual patient presenting with DSD conditions must be fully considered, along with the needs of their families and where appropriate, cultural practices. The multidisciplinary team should be involved from early in the diagnosis and ethical principles must be considered at all stages of management of the condition.

Key Concepts:

• Disorders of sex development usually present in the newborn or adolescent periods.
  
• There are three broad groups of DSD: sex chromosome DSD; 46,XY DSD and 46,XX DSD.
  
• Where there is uncertainty about the sex of a patient, sex assignment should be delayed until appropriate investigations have been carried out.
  
• A multidisciplinary team should be involved from an early stage.
  
• The psychosocial implications of a diagnosis of DSD must be considered for the family and the patient.