Incontinentia pigmenti (IP) is one of several ectodermal dysplasias, which are disorders that affect the outer layer of a developing embryo. This layer, called the ectoderm, develops into many parts of a baby's body, including the eyes, skin, nails, and hair. In ectodermal dysplasias, these parts may not develop normally.
IP is a rare inherited genetic disorder that is similar to a condition called hypomelanosis of Ito (HI), formerly known as IP type 1 or IP1. The characteristic feature of HI is hypopigmentation, or the lack of melanin, the pigment that gives color to the skin and hair, resulting in only a little or no color in the skin and hair. Unlike HI, IP presents with skin discoloration caused by excessive deposits of melanin. In IP, melanin collects in the skin, causing wavy lines and streaks that are gray, blue, or brown in color. Many people classify HI as a "negative image" of IP. IP is often referred to as a neurocutaneous condition because it affects the nervous system and the skin.
IP affects the skin, eyes, hair, teeth, nails, and the central nervous system, which includes the brain and spinal cord. Skin problems are the most common symptom of IP and tend to be apparent at birth or within two weeks of birth. People with IP may also have severe vision loss, cataracts, or crossed eyes; missing or peg-shaped teeth; and poorly developed hair and nails.
Neurological problems in IP include wasting away of the brain tissue, formation of small holes in the brain tissue, and the loss of nerve cells. Additional symptoms of IP include intellectual disabilities, seizures, muscle weakness in one or both sides of the body, and slow motor development.
IP is caused by a mutation in the NEMO gene (also known as IKBKG). The NEMO gene provides instructions for making the NEMO protein, which is important for the immune system and for the health of cells. NEMO is also involved with the development of the skin, eyes, teeth, and hair.
People with IP may be at higher risk for certain types of cancer, such as leukemia, because of instability in the chromosomes. Although the skin abnormalities usually become less apparent and sometimes disappear completely, there may be residual neurological difficulties.
The incidence of incontinentia pigmenti is one in 40,000 individuals worldwide, and it is more common in Caucasians than in other races. Incontinentia pigmenti usually affects only females, because it is an X-linked dominant disease; male fetuses usually do not survive.
Bloch-Siemens incontinentia pigmenti melanoblastosis cutis linearis, Bloch-Siemens-Sulzberger syndrome, Bloch-Sulzberger disease, Bloch-Sulzberger syndrome, incontinentia pigmenti type 2, IP, NEMO, neurocutaneous condition, pigmented dermatosis Siemens-Bloch type, skin pigmentation disorder, X-linked inherited disorder.