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X-linked Dominant: Incontinentia Pigmenti

Genes are inherited from our biological parents in specific ways. One of the basic patterns of inheritance of our genes is called X-linked dominant inheritance.

What is X-linked dominant inheritance?

X-linked dominant inheritance occurs when a gene responsible for a trait or disorder is located on the X chromosome. The gene acts in a dominant manner. This means that both males and females can display the trait or disorder when they have only one copy of the gene inherited from a parent.

Genetic illustration demonstrating X-linked dominant inheritance
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Depending on the disorder, a gene that is X-linked dominant may cause a pregnancy with a male not to survive. Scientists and doctors say that there is "lethality" in males. This means that the gene can be passed from mother to daughter, but if passed to a son, then the pregnancy miscarries. Only those sons without the gene survive and are born healthy. One example of an X-linked dominant condition is called incontinentia pigmenti (IP).

What is incontinentia pigmenti?

IP is extremely rare. The main features occur in the skin where a blistering rash occurs in newborns. This is followed by the blisters becoming raised, like warts. Next, brown swirls appear in the skin, followed by the appearance of light-colored swirls. The result is a "marble-cake–like" appearance on the skin. Other health problems can be seen in IP involving the eyes, central nervous system, teeth, nails, and hair. The severity varies from person to person.