Deletions of distal 9p associated with 46,XY male to female sex reversal: definition of the breakpoints at 9p23.3-p24.1.

Monosomy of distal 9p is associated in rare cases with abnormalities of testicular determination, which can lead to male to female sex reversal in a 46,XY genetic background. We present two 46,XY individuals partially monosomic for 9p who were raised as females. Definition of the breakpoints using somatic cell hybrids containing only the rearranged chromosome 9 indicated that in the first patient the breakpoint was located between markers D9S256 and D9S144 and in the second patient, the breakpoint was distal to the marker D9S144. In both cases this corresponds to the cytogenetic position 9p23.3-p24.1. Analysis of highly polymorphic microsatellite markers demonstrated a paternal origin of the rearranged chromosome 9 in both patients. These studies define the minimum region associated with male to female sex reversal as 9p24.1-pter.