Differences in Sex Development

This chapter presents an overview of the pathophysiology of differences in sex development (DSD), including a discussion of the practical aspects of diagnosis and management. There are four general causes of DSD: (1) androgenization of the 46,XX individual, (2) incomplete androgenization of the 46,XY individual, (3) sex gonadal differentiation and chromosomal disorders, and (4) syndromes associated with incomplete genital development. The first category, 46,XX DSD, comprises the majority of definable cases of ambiguous genitalia, whereas in the second category, 46,XY DSD, a genetic diagnosis is seen in less than 50% of cases. An overview of the traditional surgical methods used in the treatment of infants with DSD, including the risks and benefits of these procedures, is included at the end of the chapter.