Genetics
IP is inherited in an X-linked dominant manner. IP is lethal in most, but not all, males. A female with IP may have inherited the IKBKG mutation from either parent or have a new gene mutation. Parents may either be clinically affected or have germline mosaicism. Affected women have a 50% risk of transmitting the mutant IKBKG allele at conception; however, most affected male conceptuses miscarry. Thus, the expected ratio for liveborn children is 33% unaffected females, 33% affected females, and 33% unaffected males. Genetic counseling, prenatal testing, and preimplantation genetic diagnosis is available.
In females, the cells expressing the mutated IKBKG gene due to lyonization selectively die around the time of birth so the X-inactivation is extremely skewed.
IP is caused by mutations in a gene called NEMO (NF-kappaB essential modulator).
Read more about this topic: Incontinentia Pigmenti