A Novel Splicing Mutation Identified in a Chinese Family with X-linked Alport Syndrome Using Targeted Next-Generation Sequencing.

AIMS: Alport syndrome (AS) is a genetically heterogeneous disorder, characterized by hematuria, progressive renal failure, sensorineural hearing loss, and ocular abnormalities caused by mutations in the COL4A3, COL4A4, and COL4A5 genes. The aim of this study was to identify underlying mutations in individuals from a Chinese family with X-linked AS.

METHODS: We performed targeted next-generation sequencing (NGS) to identify mutations associated with AS. The results were processed and visualized using an Integrated Genomics Viewer software. The most likely disease-causing variants were identified and confirmed by Sanger sequencing of reverse transcription-polymerase chain reaction products.

RESULTS: Visual inspection using Integrative Genomics Viewer software found that COL4A5 exon 10 was not covered by the disease panel, while coverage of exons 4, 17, 20, 21, 37, and 45 was incomplete. Sanger sequencing of these regions identified a novel splice-site mutation in intron 9 (c.547-3C>A) of the COL4A5 gene. Subsequent cDNA analysis revealed that c.547-3C>A led to skipping of exon 10, which resulted in an in-frame deletion of 21 amino acids from the α5 chain of type IV collagen.

CONCLUSION: We determined the molecular basis of AS in a Chinese family by targeted NGS and cDNA analysis. This is the first report of the novel c.547-3C>A splicing mutation in the collagen domain of COL4A5 gene.