Researchers on Wednesday unveiled the first complete sequence of the human Y chromosome, which is one of the two sex chromosomes - the X chromosome being the other - and is typically passed down ...

Sex chromosomes are the genetic elements that define a person's biological sex. Learn about the XX and XY chromosomes, the sex determination system, and other chromosome combinations.

As many as one in 500 men may carry an extra sex chromosome — either an X or a Y — but very few of them likely know about it, a new study suggests.