Abstract

Mammals have a very complex, tightly controlled, and developmentally regulated process of dosage compensation. One form of the process equalizes expression of the X‐linked genes, present as a single copy in males (XY) and as two copies in females (XX), by inactivation of one of the two X‐chromosomes in females. The second form of the process leads to balanced expression between the X‐linked and autosomal genes by transcriptional upregulation of the active X in males and females. However, not all X‐linked genes are absolutely balanced. This review is focused on the recent advances in studying the dosage compensation phenomenon in mammals.