What is incontinentia pigmenti?
Incontinentia pigmenti, or IP, is an inherited disorder of skin coloring (pigmentation). Other symptoms involve the teeth, skeletal system, eyes, and brain. The defining symptom in IP is skin problems that change over time. Many affected infants have a blistering rash at birth. The rash heals and is followed by the development of wart-like skin growths. The skin develops grey or brown patches (hyperpigmentation) in early childhood. These patches occur in a swirled patterns and fade with time. Adults with IP usually have lines of unusually light-colored skin (hypopigmentation) on their arms and legs.
Other signs and symptoms of incontinentia pigmenti can include:
- Hair loss (alopecia) affecting the scalp and other parts of the body
- Dental abnormalities (such as small teeth or few teeth)
- Abnormal breast tissue
- Eye abnormalities that can lead to vision loss
- Lined or pitted fingernails and toenails.
- Delayed development or intellectual disability
Not all affected people have all of these symptoms. Most affected individuals have normal intelligence. This condition occurs much more often in females than in males. Miscarriage usually occurs when the pregnancy is male. IP is caused by mutations in a gene called IKBKG. This gene is found on the X chromosome. Chromosomes are the structures that hold all of our genetic information. We have 23 pairs of chromosomes and one of these pairs determines a baby’s sex. The pair that determines sex are the X and Y chromosomes. Females usually have two X chromosomes and males have one X and one Y chromosome. The IKBKG gene is found on the X chromosome. Since females have an extra copy of the X chromosome, they have an extra copy of the IKBKG gene. If one copy is not working correctly, they have a backup copy. This is why females with IP survive and are less severely affected.
IP is usually diagnosed and treated by a doctor called a medical geneticist. Talk to a medical geneticist to learn more about the symptoms and inheritance of incontinentia pigmenti. To find a medical geneticist near you, visit the Genetic Services Search Engine on the American College of Medical Genetics website.