Monilethrix.

Sir,

A 9-year-old boy born of second degree consanguineous marriage presented with inability to grow hair associated with diffuse sparseness since childhood [Figure 1]. Patient's mother denied any history of pulling of hair by the child. According to the mother, loss of hair had begun from the age of 1 year. No family members were affected. The nails and teeth were normal. Physical and neurological examination was normal with proper development of milestones. Hematological investigations were within normal limits.

Figure 1

Patient with diffuse sparseness of hair over the scalp with multiple papules over nape of neck and occipital region

On cutaneous examination, hair was short, stubby with multiple keratotic hyper pigmented papules all over scalp mainly involving nape of the neck and the occipital area. Hair pull test was negative. Trichogram showed characteristic beaded appearance of scalp hair shaft [Figure 2]. Hence based on the clinical and trichogram analysis, the diagnosis of monilethrix was made.

Figure 2

Trichogram showing characteristic periodic narrowing with the nodes giving beaded appearance of hair shaft

Monilethrix word is derived from Greek language meaning “The Beaded Hair.” Monilethrix is a rare hereditary hair shaft disorder usually inherited as an autosomal dominant trait with variable penetrance, but may rarely present as autosomal recessive.[12]

In majority of cases, it is caused by mutations in the trichocyte keratin genes Type II encoding hHb1, hHb3 and hHb6 present over chromosome 12q11-q13. Recently, they found mutation in exon 1 and 7 of KRT86, KRT 81 and KRT 83 gene in autosomal dominant trait and mutation in desmoglein 4 was associated with autosomal recessive type of monilethrix. It is found that mutation in hHb1usually leads to less severe type of monilethrix with normal hair at birth, but develop hair shaft defects after a few months. While remaining keratin gene mutations (hHb3 and hHb6) lead to severe forms involving body hair including the eyebrows and the eyelashes. Nails may show Koilonychia.[34]

In monilethrix, “regularly bended ribbon sign” is suggested in order to differentiate it from pseudomonilethrix as monilethrix shows bends at regular intervals.[2]

There is no effective way of treatment for monilethrix. Many single case reports showing improvement with topical 2% minoxidil, biotin, N-acetyl cysteine, acitretin, steroids, oral contraceptive pills and griseofulvin have been reported with some showing spontaneous improvement. The most effective method is avoidance of trauma to congenitally abnormal hair.[14]