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Incontinentia pigmenti is a condition affecting many body systems, particularly the skin. This disorder, which occurs mainly in females, is characterized by blistering and wart-like skin growths in early childhood followed by changes in skin pigmentation. The condition may also affect the teeth, hair, eyes, and central nervous system (the brain and spinal cord).
Incontinentia pigmenti is an uncommon disorder. Between 700 and 1,000 affected individuals have been reported in the scientific literature.
Mutations in the IKBKG gene cause incontinentia pigmenti.
The IKBKG gene provides instructions for making a protein that helps regulate the activity of nuclear factor-kappa-B. Nuclear factor-kappa-B is a protein complex that normally helps protect cells from self-destructing (undergoing apoptosis) in response to certain signals. In about 80 percent of affected individuals, mutations in the IKBKG gene lead to an abnormally small, nonfunctional version of the IKBKG protein. Other people with incontinentia pigmenti have mutations that prevent any IKBKG protein from being produced. Without this protein, nuclear factor-kappa-B is not regulated properly, and cells are more likely to undergo apoptosis. Researchers believe that this abnormal cell death leads to the signs and symptoms of incontinentia pigmenti.
This condition is inherited in an X-linked dominant pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. The inheritance is dominant if one copy of the altered gene in each cell is sufficient to cause the condition. In most cases, males experience more severe symptoms of the disorder than females. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
In some cases, an affected person inherits the mutation from one affected parent. Other cases may result from new mutations in the gene. These cases occur in people with no history of the disorder in their family.
Research suggests that incontinentia pigmenti occurs mainly in females because males with mutations in the IKBKG gene usually die before birth. Males with these mutations have no functional IKBKG protein in any of their cells. In females with incontinentia pigmenti, some cells produce normal protein from the IKBKG gene and other cells produce no functional IKBKG protein. The resulting overall reduction in the amount of functional IKBKG protein leads to the signs and symptoms of incontinentia pigmenti.
'''Incontinentia pigmenti''' (IP) is a disorder that affects the skin, hair, teeth, and nails. The skin lesions evolve through characteristic stages: 1) blistering (from birth to about four months of age), 2) a wart-like rash (for several months), 3) swirling macular hyperpigmentation (from about six months of age into adulthood), followed by 4) linear hypopigmentation. Alopecia, hypodontia, abnormal tooth shape, and dystrophic nails are observed. Some patients have retinal vascular abnormalities predisposing to retinal detachment in early childhood. Cognitive delays/mental retardation are occasionally seen. The diagnosis of IP is established by clinical findings and occasionally by corroborative skin biopsy. Molecular genetic testing of the IKBKG gene (chromosomal locus Xq28) reveals disease-causing mutations in about 80% of probands. Such testing is available clinically. In addition, females with IP have skewed X-chromosome inactivation; testing for this can be used to support the diagnosis. 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 and prenatal testing is available. [ Read More ]
MCW Healthlink: Incontinentia Pigmenti - An article about this rare genetic disorder, its stages and symptoms.
Incontinentia Pigmenti - Informational sheet compiled by National Institute of Neurological Disorders and Stroke.
Readers Digest Health: IP - A general discussion about incontinentia pigmenti, with alternate names and further resources.
Incontinentia Pigmenti International Foundation - Details about the organization that is dedicated to research into the causes and treatment of this genetic disease. Includes information about the disease, genetics and genes.
Incontinentia Pigmenti: All About Anna - The authors' daughter was diagnosed with IP 6 weeks after birth. This is her story.
Incontinentia pigmenti France (IPF) - Présentation de la maladie, de lassociation et de ses actions, actualités et liens.