Long term follow-up of a child with ambiguous genitalia, mixed gonadal dysgenesis, and unusual mosaicism.

Mixed gonadal dysgenesis (MGD) is a condition of abnormal and asymmetrical gonadal development. This disorder is typically associated with 45,X/46,XY mosaicism; however, other karyotypes have been rarely reported. The phenotype characterizing MGD is highly variable, although in most cases ambiguous genitalia are found. In addition, many individuals with MGD exhibit stigmata of Turner's syndrome. We describe a patient with MGD, found to have a 45,X/47,XYY karyotype, with the majority of the cell lines being 47,XYY. To our knowledge, our report is the first to describe the long-term follow-up of a patient with ambiguous genitalia diagnosed at birth with 45,X/47,XYY mosaicism.