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​X Chromosome

updated: July 20, 2024


The X chromosome is one of the two sex chromosomes that are involved in sex determination. Humans and most other mammals have two sex chromosomes (X and Y) that in combination determine the sex of an individual. Females have two X chromosomes in their cells, while males have one X and one Y.



X chromosome: Humans and many other mammals have one pair of sex chromosomes in each cell. Females have two X chromosomes, while males have one X and one Y chromosome. The chromosome X represents about 5% of a cell's total DNA and likely contains about 900 genes.

Belen Hurle
Belen Hurle, Ph.D.

Former Associate Investigator

Division of Intramural Research