Partial androgen insensitivity syndrome is a genetic condition that is inherited in an X-linked recessive pattern. The gene related to partial androgen sensitivity syndrome is the AR gene, which is located on the X chromosome. When people have a change in the AR gene, their bodies may have issues producing androgen receptors, which are structures in cells that allow the body to properly respond to androgens (male sex hormones). Because of problems with the androgen receptors, people with changes in the AR gene have the characteristics of partial androgen sensitivity syndrome.
Chromosomes are located in the nucleus of human cells and carry the genetic information (DNA) for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes numbered from 1 through 22 are called autosomes and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes.
X-linked genetic disorders are conditions caused by an abnormal gene on the X chromosome and manifest mostly in males. Females that have an altered gene present on one of their X chromosomes are carriers for that disorder. Carrier females usually do not display symptoms because females have two X chromosomes and only one carries the altered gene. Males have one X chromosome that is inherited from their mother and if a male inherits an X chromosome that contains an altered gene he will develop the disease.
Female carriers of an X-linked disorder have a 25% chance with each pregnancy to have a carrier daughter like themselves, a 25% chance to have a non-carrier daughter, a 25% chance to have a son affected with the disease and a 25% chance to have an unaffected son.
If a male with an X-linked disorder is able to reproduce, he will pass the altered gene to all of his daughters who will be carriers. A male cannot pass an X-linked gene to his sons because males always pass their Y chromosome instead of their X chromosome to male offspring.