Female pseudohermaphroditism with multiple caudal anomalies: absence of Y-specific DNA sequences as pathogenetic factors.

46,XX female pseudohermaphrodites have been previously described with nearly complete masculinization of the external genitalia and no apparent source of testosterone. Multiple malformations of internal genital, urinary, and gastrointestinal tracts are associated. We have evaluated four such infants with female pseudohermaphroditism and multiple caudal anomalies. Three cases had apparently normal chromosomes (46,XX); one had a 46,XX,del(10)(q25.3-->qter) chromosome constitution. The chromosome breakpoint is in the region of PAX2, a developmentally important paired box gene which is expressed in urogenital tissue. Using the polymerase chain reaction, we screened for the presence of multiple Y specific sequences, including SRY (sex determining region, Y chromosome), that could explain masculinization of the external genitalia. All were negative for Y centromeric sequences, ZFY (Zinc finger Y), and SRY. Furthermore, there was no evidence for adrenal or other sources of testosterone. We suggest that the masculinization in these cases is the result of abnormal expression of genes which would normally be regulated by testosterone.