Partial Xp duplication due to a translocation t(X;15) in two male and two female patients: a familial case report and review of the literature.

A three generation familial translocation (X;15)(p22;p11) is responsible for duplication (X)(pter-->p22) in two male and two female patients. It is present in a balanced state in the mothers and with the derivative chromosome 15 in the children. The Xp segment of the derivative chromosome 15 is separated from the X inactivation center and cannot undergo X inactivation. As a result, there is functional disomy of Xp in the male and female patients that is responsible for mental retardation and other phenotypic findings.