X-linked dominant

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X-linked dominant is mode of inheritance in which a gene on the X chromosome is dominant<ref>X-linked Dominant: Incontinentia pigmenti - Lucile Packard Children's Hospital</ref>. Females are more frequently affected than males, although any X-linked dominant gene is not sex linked. The chance of passing on an X-linked dominant disorder differs between men and women.

This inheritance pattern is less common than X-linked recessive.

[edit] Inheritance

Females usually have two X chromosomes, while most males have one X and one Y chromosome. If a child has inherited the mutation from the X chromosome of one of their parents they will have the condition. A woman with an X-linked dominant disorder has a 50% chance of having an affected daughter or son with each pregnancy. The sons of a man with an X-linked dominant disorder will not be affected, but his daughters will all inherit the condition.

A woman with an X-linked dominant disorder has a 50% chance of having an affected child.

The daughters of a man with an X-linked dominant disorder will all inherit the condition.

Some X-linked dominant conditions such as Aicardi Syndrome are fatal to boys, therefore only girls with these conditions survive. Similarly, individuals with Klinefelter's Syndrome are referred to as "47,XXY Males".