X-Chromosome inactivation (XCI) patterns in placental tissues of a paternally derived bal t(X;20) case

Abstract

Objective: Non-random X-chromosome inactivation (XCI) is often seen in female carriers of balanced X;autosome translocations and is generally attributed to a selective growth of cells that inactivate the normal X chromosome. However, little is known concerning when in development the selection acts, and thus whether skewed XCI would also be seen in placental tissues. Furthermore, as males with X-autosome translocations are normally infertile, all translocations studied to date for XCI-skewing have been either maternal or de novo in origin. However, we have recently reported the transmission of a balanced X;autosome translocation involving chromosomes X and 20 from father to daughter with the use of intracytoplasmic sperm injection (ICSI). This case thus provides a unique opportunity to examine the process of X-chromosome inactivation during placental development, and we report the analysis of XCI patterns in placental tissues and cord blood from this female.