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.