40:1 000 000 inhabitants
This disorder is caused by changes (mutations) in the gene referred to as NEMO. This gene is of significance in relation to inflammations, the immune defense system and programmed cell death. It is assumed that this genetic mutation disturbs the development of several organs in the foetus (ectodermal tissues) . Incontinentia pigmenti (IP) is inherited as an X-linked dominant trait. Symptoms occur almost exclusively in girls and women, who have two X chromosomes, only one of which is normal in these cases. Boys are not born with the disorder, since male foetuses carrying the genetic defect do not usually survive to term.
The severity of symptoms may vary even within one and the same family. Skin symptoms occur in virtually all cases. Stage 1: as early as at birth, there may be fluid-filled blisters. These blisters disappear by the age of approximately 4 months. Stage 2 is characterized by wart-like, chain shaped bumps, usually in the arms and legs and in the scalp. These disappear in most cases by the age of 6 months. Stage 3 is characterized by increased pigmentation of patches of skin, in a swir led pattern This stage is also accountable from the name of the disease, incontinentia pigmenti. Stage 4 is characterized by pale, hairless patches of skin, usually on the legs. The functions of the salivary and sweat glands may be impaired. Visual impairments such as myopia, squinting, cataract or vision problems caused by retinal changes commonly occur. Other symptoms include bald spots on the scalp, or thin, br ittle hair and the absence of nails, or nails with ridges or pitting. There may also be symptoms from the nervous system, the most frequent being one or more episodes of cramps during infancy. These have no lasting detrimental effects. Individuals with IP may also have reading and writing difficulties or delayed intellectual and/or motor development.
Impaired salivary gland function may result in a dry mouth and a corollary risk of increased caries. Many individuals with IP may be missing one or more teeth altogether, and late eruption of both primary and permanent teeth is common. It is also common that the teeth display anomalies of shape, for instance they may be small, conical or irregular.
- Children with IP should be referred to a paediatric dental specialist for examination and treatment planning.
- Regular check-ups of dental and jaw development. Orthodontist should be consulted when needed.
- Individuals with dysfunctional sweat glands should not be unnecessarily exposed to heat.
- The rare diseases database of the Swedish National Board of Health and Welfare.
- The MHC database - The Mun-H-Center database on oral health and orofacial function in rare diseases.