Monilethrix: A Rare Inherited Hair Shaft Disorder in Siblings

Monilethrix is a rare inherited hair shaft disorder characterized by a beaded appearance of the hair due to alternating thick and thin segments, leading to fragile hair that breaks easily. An 8-year-old boy and his 10-year-old sister, both children of a nonconsanguineous marriage, presented with symptoms of monilethrix, including easy breakability of hair and follicular papules on the nape of the neck. Microscopic examination confirmed the diagnosis, showing the characteristic beaded hair shafts. The disorder is typically autosomal-dominant with variable penetrance and is caused by mutations in the genes encoding type 2 hair keratins. The siblings exhibited variable severity of the condition, with the boy being more affected. Although treatments like griseofulvin, retinoids, topical 2% minoxidil, and oral N-acetyl cysteine have provided temporary improvement in some cases, there is currently no effective treatment for monilethrix.