Summary

• Congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical. A subset of these children presents at birth with ambiguous genitalia (i.e., a genital phenotype that is neither clearly male nor female).
• Can be classified as sex chromosomal, 46,XX, or 46,XY disorders of sexual development (DSD).
• Over 95% of DSD with a 46,XX genotype are due to 21-hydroxylase deficiency causing congenital adrenal hyperplasia.
• Mixed gonadal dysgenesis is the most common form of sex chromosomal DSD and the second most common cause of all DSD. It has a varied presentation.
• 46,XY DSD can be due to several aetiologies and requires a more extensive diagnostic evaluation.
• Diagnosis in a child with ambiguous genitalia is a clinical emergency that should be managed in an institution with expertise in endocrinology, genetics, and surgery, and with appropriate psychosocial support.
• Management usually includes a combination of surgery and hormonal treatment.
• Long-term medical outcome is very good, although there may be physical and psychological consequences.