Monilethrix

Genetic disorder affecting the hair and occasionally the skin; does not belong to the group of ectodermal dysplasias.

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Unknown. It is an autosomal dominant disorder. The cause of this disease seems to be a mutation in the genes responsible for the hair keratin, which has been mapped to 12q13.

Although the symptoms of these syndromes may resemble ectodermal dysplasia, monilethrix does not belong to this group. It is characterized by a beaded appearance of the scalp hair caused by periodic narrowing of the hair shaft. Phenotypically, this results in breakage of the hair (brittle, dry, lusterless look) and patchy alopecia. The onset is usually in infancy, and symptoms may ameliorate to a certain degree after puberty and during pregnancy. Hair outside of the scalp area (pubis, axilla, eyelashes, eyebrows) is occasionally affected. Some patients show signs of koilonychia and follicular keratosis. Over the years, skin atrophy may develop in affected areas.

These patients are otherwise healthy and do not require any specific anesthetic precautions.