Whole Exome Sequencing Identifies a Novel Frameshift Mutation of the WRN Gene in a Werner Syndrome Family and Functional Analysis.

Introduction: Werner syndrome (WS) is a rare recessive disorder characterized by premature aging and metabolic abnormalities. WS is caused by mutations in the WS RecQ-like helicase gene (WRN), which encodes the WRN RecQ-like helicase protein. This study aimed to identify the deletion mutation in the WRN gene within the WS family and comprehensively analyze its regulatory role.

Methods: We utilized whole exome sequencing to assess gene mutations in non-close relatives of two patients with WS. The mutation was further verified using Sanger sequencing. Subsequently, the pathophysiological characteristics of the mutation were examined using Western blotting, subcellular localization determination, conservative analysis, and three-dimensional (3D) protein structure prediction.

Results: Whole exome sequencing revealed a previously unreported homozygous mutation c.3244delG (p.Val1082Tyrfs*17) within exon 27 of the WRN gene. Sanger sequencing confirmed the presence of a homozygous mutation in the two patients, while a heterozygous mutation was identified in the other six family members. Western blotting revealed that the c.3244delG mutation in the WRN gene resulted in a reduced molecular weight of the mutated WRN protein. Furthermore, subcellular localization experiments revealed that the mutant WRN protein could not be effectively transported to the nucleus. Some studies reported that the mutation exhibits a high conservation rate across various species. The three-dimensional structure prediction indicates that the mutant WRN protein exhibits a distinct structure compared to the wild-type protein.

Conclusions: This study identified a frameshift mutation in the WRN gene, which was associated with WS. The subsequent functional analysis revealed the inefficiency of the mutated protein. This study broadens the spectrum of known WRN mutations and enhances the comprehension of WS pathogenesis.