Analysis of a Familial IgAN Accompanied by COL4A3 Mutation.

Objective: IgA nephropathy (IgAN) is the prevailing primary glomerulonephritis globally and is the key factor contributing to the onset of chronic kidney disease and eventual progression to end-stage renal disease. This study aims to explore the mutated gene in a familial case of IgAN, especially COL4A3.

Methods: Family lineages diagnosed with familial IgAN at the Longyan First Hospital of Fujian Medical University were selected for this study, followed by comprehensive whole exome sequencing. After obtaining the sequencing data, bioinformatics analyses were conducted to discern potential mutated genes. These findings within the familial lineages were validated using Sanger sequencing to identify IgAN-associated mutated genes, based on literature references and in accordance with the genetic variation classification criteria determined by the American College of Medical Genetics and Genomics.

Results: Whole exome sequencing analysis of familial IgAN family lineages led to the identification of a total of 212,187 single nucleotide variant/insertion-deletion mutation sites, annotated using ANNOVAR. These sites were screened targeting four mutated genes, revealing three mutations of undetermined significance along with a single disease-causing mutation: a heterozygous disease-causing mutation within COL4A3 (p.G1167R). This mutation manifested across seven family members within the group, encompassing both family members diagnosed with kidney disease and those serving as normal carriers. Notably, one additional family member with IgAN within the familial lineage exhibited an absence of the pathogenic mutation.

Conclusion: This study identified four mutated genes that may be involved in the onset and progression of IgAN, further revealing the complex multigenic inheritance characteristics of IgAN. The underlying mechanisms of the disease require further investigation. Additionally, we discovered potential mutations associated with known genetic kidney diseases, such as COL4A3 mutations. Therefore, we recommend comprehensive genetic screening in familial cases of IgAN to improve disease diagnosis and facilitate genetic counseling.