A clinical and cytogenetic study of fifteen patients with 45,X/46XY gonadal dysgenesis.

The cytogenetic and phenotypic findings in 15 patients with 45,X/46,XY mosaicism are described. Six patients presented with delayed sexual development without masculinization. The remaining nine patients had varying degrees of masculinization, ranging from clitoromegaly to hypospadic male phenotypes. Cardiovascular/renal anomalies were detected in 2 of the 15 patients. Gonadoblastomas were present in two patients and did not appear to correlate with the degree of masculinization or percentage of 46,XY cells present. Structural Y chromosome abnormalities were seen in three of the 45,X/46,XY probands. MZ twinning occurred in one of the 45,X/46,XY sibships.