The sex chromosomes form one of the 23 pairs of human chromosomes in each cell. The Y chromosome spans more than 59 million building blocks of DNA (base pairs) and represents almost 2 percent of the total DNA in cells.
Each person normally has one pair of sex chromosomes in each cell. The Y chromosome is present in males, who have one X and one Y chromosome, while females have two X chromosomes.
The Y chromosome likely contains 50 to 60 genes that provide instructions for making proteins. Because only males have the Y chromosome, the genes on this chromosome tend to be involved in male sex determination and development.
Male sex determination
Sex is determined by the SRY gene, which is responsible for the development of a fetus into a male. Other genes on the Y chromosome are important for enabling men to father biological children (male fertility).
Many genes are unique to the Y chromosome, but genes in areas known as pseudoautosomal regions are present on both sex chromosomes. As a result, men and women each have two functional copies of these genes. Many genes in the pseudoautosomal regions are essential for normal development.
- 46,XX testicular disorder of sex development
- 47,XYY syndrome
- 48,XXYY syndrome
- Y chromosome infertility
- Other chromosomal conditions