Abstract: Monilethrix is an autosomal dominant genodermatosis with hair shafts and hair follicles abnormal. We reported 4 cases with monilethrix and all presented with hair fragility, keratosis pilaris and poor growth. Out of 4 patients, 3 had family histories of monilethrix. Dermoscopy of the hair shaft showed elliptical nodes separated by narrower internodes in all patients. Mutations of c.1204G＞A and c.1237G＞A in KRT86 gene were detected in the two patients respectively. 

Key words: monilethrix, KRT86 gene, dermascopy