Genetic disorder affecting the hair and occasionally
the skin; does not belong to the group of ectodermal dysplasias.
Brittle, dry hair in a teenager with monilethrix. The eyebrows and
eyelashes are also affected.
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.
Despontin K, Krafchik B: What syndrome is this? Monilethrix syndrome. Pediatr Dermatol
Ito M, Hashimoto K, Yorder FW: Monilethrix: An ultrastructural study. J Cutan Pathol
Stevens HP, Kelsell DP, Bryant SP: Linkage of monilethrix to the trichocyte
and epithelial keratin gene cluster on 12q11-q13. J Invest Dermatol