Trades Union Congress. Archived from the original on 2013-05-25. –  basic facts
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The hair is seen under a microscope with bumps in the hair strand. These cause the hair to be brittle and break in the thinner sections. Severe cases of monilethrix can also effect finger and toe nails causing abnormal growth. Monilethrix can also cause keratosis pilaris (small bumps on the skin). Less severe cases of Monilethrix may only affect certain parts of the scalp, usually the back of the head and neck. Diagnosis
Monilethrix may be diagnosed with trichoscopy and other forms of dermoscopy. Light microscopic examination is diagnostic and reveals elliptical nodes of normal thickness and intermittent constrictions, internodes at which the hair easily breaks. Under examination, the hair is beaded. The beading is the result of a periodic narrowing of the shaft with nodes separated by about 0.7 mm. In general, there is a tendency for spontaneous improvement with time, especially during puberty and pregnancy, but the condition never disappears completely. Genetics
Monilethrix is caused by mutations affecting the genes KRTHB1 (KRT81), KRTHB3 (KRT83), or KRTHB6 (KRT86) which code for type II hair cortex keratins. The disorder is inherited in an autosomal dominant manner. This means that the defective gene(s) responsible for the disorder is located on an autosome, and only one copy of the gene is sufficient to cause the disorder, when inherited from a parent who has the disorder. If an affected parent and an unaffected parent have children, 75% of the time they will be affected by Monilethrix. It can be equally present in both males and females.