Synergistic toxicity of compound heterozygous mutations in the COL4A3 gene causes end-stage renal disease in A large family of Alport syndrome

Longxin Xie; Yuxi Ding; Ying Qiu; Yi Shi

doi:10.1016/j.gene.2024.149132

Synergistic toxicity of compound heterozygous mutations in the COL4A3 gene causes end-stage renal disease in A large family of Alport syndrome

Gene. 2024 Nov 28:149132. doi: 10.1016/j.gene.2024.149132. Online ahead of print.

Authors

Longxin Xie¹, Yuxi Ding², Ying Qiu³, Yi Shi⁴

Affiliations

¹ Physician-Scientist Program, School of Medicine, Tsinghua University, Beijing 100084, China; Department of Kidney Transplantation, Center of Organ Transplantation, Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing 102218, China. Electronic address: xielx18@mails.tsinghua.edu.cn.
² Physician-Scientist Program, School of Medicine, Tsinghua University, Beijing 100084, China; Department of Kidney Transplantation, Center of Organ Transplantation, Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing 102218, China.
³ Physician-Scientist Program, School of Medicine, Tsinghua University, Beijing 100084, China. Electronic address: yingqiu2009@tsinghua.edu.cn.
⁴ Department of Kidney Transplantation, Center of Organ Transplantation, Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing 102218, China. Electronic address: sya03071@btch.edu.cn.

PMID: 39615805
DOI: 10.1016/j.gene.2024.149132

Abstract

Alport syndrome (AS) is a genetic disorder characterized by kidney disease and hearing/vision abnormalities, resulting from mutations in the COL4A3, COL4A4, or COL4A5 genes. While numerous mutations have been identified in AS cases, the precise molecular mechanisms, particularly for compound mutations, remain under investigation. This study investigated the molecular mechanisms of AS in a proband with end-stage kidney disease (ESKD) using whole exome sequencing, which identified two compound heterozygous COL4A3 missense mutations: NM_000091.5:c.1354G > A (p.G452R) and NM_000091.5:c.4793 T > G (p.L1598R). Sixteen family members of the proband were genotyped, and further analyses, including in silico structural prediction, molecular docking, and in vitro co-immunoprecipitation assays, revealed that the p.G452R mutation disrupted the collagen triple helical structure, associated with hematuria in carriers, while the p.L1598R mutation interfered with the interaction between the NC1 domains of COL4A3 and COL4A4 proteins, crucial for collagen trimerization. These findings demonstrate a synergistic loss-of-function effect of the two mutations, contributing to the AS pathogenesis in the proband, and emphasize the importance of genetic screening and personalized treatment strategies for AS.

Keywords: Alport syndrome; COL4A3; Compound heterozygous; Molecular model; type IV collagen.