Mixed-gonadal dysgenesis, or MGD, is a rare condition in which the paired internal gonads (testis or ovary) are different on each side. There is usually a functioning gonad (testis or ovary) on one side and an atypical, non-functioning gonad or "streak" on the other side.
The condition has been associated with a variety of chromosome combinations where some cells may have normal numbers of chromosomes, where others may have too few or too many. The physical appearance of the genitalia is variable, ranging from typical male to typical female, or sometimes in between. Gender of rearing with MGD is individualized, and multiple factors are taken into consideration.
The diagnosis is typically made through laboratory and genetic testing. Sometimes surgical biopsy is required for confirmation.
Treatment may include surgical removal of precancerous gonads, hormone replacement therapy, and sometimes surgical reconstruction.