Hidden X chromosomal mosaicism in a 46,XX male.

We report on a 37-year-old XX male with complex hidden X chromosomal mosaicism. The patient had fully mature male genitalia with hypoplastic testes descended in the scrotum and no sign of undervirilization. Hormonal examination demonstrated hypergonadotropic hypogonadism, semen analysis showed severe oligoasthenoteratozoospermia. In situ hybridization revealed the presence of 3 SRY-positive cell lines bearing 1, 2 or 3 X chromosomes. Skewed inactivation of the paternal SRY-bearing X chromosome was detected by molecular analysis of the androgen receptor gene.