BRIEF REVIEW

X Inactivation, Female Mosaicism, and Sex Differences in Renal Diseases

McKusick-Nathans Institute of Genetic Medicine, Department of Pediatrics, Johns Hopkins University, Baltimore Maryland

¹ To whom correspondence should be addressed. E-mail: bmigeon{at}jhmi.edu.

	Abstract

A good deal of sex differences in kidney disease is attributable to sex differences in the function of genes on the X chromosome. Males are uniquely vulnerable to mutations in their single copy of X-linked genes, whereas females are often mosaic, having a mixture of cells expressing different sets of X-linked genes. This cellular mosaicism created by X inactivation in females is most often advantageous, protecting carriers of X-linked mutations from the severe clinical manifestations seen in males. Even subtle differences in expression of many of the 1100 X-linked genes may contribute to sex differences in the clinical expression of renal diseases.