[Dicentric Y chromosome in a male pseudohermaphrodite 45,X/46,X, dic (Y)/47, XYY]

The mosaicism 45,X/46,XY,terrea(Y,Y)(pterpter)/47,XYY was observed in an 8-month-old child with male pseudohermaphroditism. The presence of a 47,XYY population points to a post-zygotic origin of the rearrangement. The loss of Yp material is in favor of localization of masculinization factor(s) to the proximal segment of Yq. Twenty-two relevant observations reported in the literature previously are discussed.