Autosomal recessive monilethrix: Novel variants of the DSG4 gene in three Chinese families

Abstract

Background: Monilethrix is a rare hereditary hair loss disorder characterized by hair fragility and beaded hair shaft alterations. Monilethrix is classically inherited in an autosomal dominant (AD) fashion caused by variants in the hair keratin genes KRT81, KRT83, or KRT86. Interestingly, an autosomal recessive (AR) form of monilethrix with variants in DSG4 gene has also been reported in recent years.

Objective: To identify causative variants in Chinese patients with autosomal recessive (AR) form of monilethrix.

Methods: Three families with AR form of monilethrix were observed and sequence variant analysis of DSG4 was performed by polymerase chain reaction (PCR), quantitative real-time PCR, and DNA sequencing.

Results: All the patients had sparse, fragile hair involving the scalp, eyebrows, and eyelashes with keratotic follicular papules and pruritus since birth. Atypical-beaded hairs and broken hair shaft fragments were identified in all the patients under dermoscopy. Heterozygous variants c.837del and c. 2389C > T, a homozygous splice site variant c.2355 + 1G > A, and a homozygous 48,644 bp large deletion variant g.31381440_31430084del in the DSG4 gene were identified and verified in the families.

Conclusion: This report provided further evidence for the phenotypic spectrum and clinical features of, and the expanded variant database of AR form of monilethrix.

Keywords: DSG4; autosomal recessive; hypotrichosis; monilethrix; variant.