Incontinentia Pigmenti Causes

Incontinentia pigmenti usually occurs in females, as it is an X-linked (inherited from the mother on the X, or female, chromosome) dominantly inherited disease that is lethal in males. This genetic disease is carried on the X chromosome. Girls have two X chromosomes, and the abnormal gene on one X chromosome is "balanced" by the normal gene on the other X chromosome.

Males, who have only one X chromosome, do not generally survive until birth if their X chromosome has the abnormal gene for IP because they lack the balancing second X chromosome that females have. Unless a passed-on gene spontaneously mutates, all mothers of girls with IP also have IP, although the extent and degree of organ involvement is extremely variable.