Q99: Other chromosome abnormalities, not elsewhere classified

Q99.0: Chimera 46,XX/46,XY

The X chromosome and the Y chromosome determine a person’s biological gender. Men normally have one X chromosome and one Y chromosome. Women normally have 2 X chromosomes.

In part of your body cells there is one X and one Y chromosome. In another part of your body cells there are 2 X chromosomes.

The reason for this lies in fertilization. A child usually comes into being when an egg is fertilized by a sperm. However, a child may develop from two fertilized eggs. One of the two fertilized eggs contains male sex hormones. The other of the two eggs contains female sex hormones. The child therefore has cells with both male sex chromosomes and cells with female sex chromosomes from the start.

Due to the different sex chromosomes, the sex organs may then develop differently than usual. Both testes and ovaries may be present. The external sex organs may look different than for most other people. During puberty, male and female sex characteristics can develop. You may not be able to have children during your lifetime.