Genetic Testing Of The COL4A5,COL4A4 And COL4A3 Genes In 48 Families With Hematuria By Exome Sequencing

Objective: This study aims to make an etiological diagnosis for families with hematuria by genetic testing of the COL4A5,COL4A4 and COL4A3 genes using exome sequencing.Methods: The clinical data and blood samples of both 48 probands and their parents with familial hematuria were collected.Genomic DNA was isolated from peripheral blood leucocytes.The probands and their parents were analyzed for variants in all coding exons and exon-intron boundaries of genes by exome sequencing.Variants which were detected in the COL4A5,COL4A4 and COL4A3 genes by exome sequencing were further verified by bi-directional Sanger sequencing.Pathogenicity of the identified variants were verified through literature reviews and bioinformatic analyses.Finally,the etiological diagnosis of 48 probands were made according to their phenotypes and their genotypes.Results: Twenty-five mutations were identified in 29 probands by exome sequencing and Sanger sequencing.Among them,20 nutations,such as COL4A5 539G>A,COL4A5 3985 del C,COL4A5 566G>T,COL4A5 2822G>A,COL4A5 EXON 29-30 deletions,COL4A4 4421C>T,COL4A4 4915G>C,COL4A4 2752G>A,COL4A4 1030-2A>C,COL4A4 2447G>A,COL4A4 4481 del T,COL4A4 4288G>A,COL4A4 1567C>T,COL4A3 1496G>A,COL4A3 3619G>A,COL4A3 3627G>A,COL4A3 4700T>G,COL4A3 898G>A,COL4A3 2096T>C and COL4A3 4769G>A,were novel,and 5 mutations,such as COL4A5 2858G>T,COL4A5 530G>A,COL4A4 4599T>G,COL4A4 3499G>A and COL4A3 4235G>T,have already been reported.Muatations in the COL4A5,COL4A4 and COL4A3 gene were found in 60.4%(29/48)of 48 probands.An etiological diagnosis could be made in 56.3%(27/48)of the probands.Eleven probands were diagnosed as X-linked Alport syndrome,and 1 proband was autosomal recessive Alport syndrome,and 15 cases were diagnosed as either autosomal dominant Alport syndrome or thin basement membrane nephropathy.Conclusion: Our results suggest that it is necessary for the families with hematuria to make an etiological diagnosis by genetic testing of the COL4A5,COL4A4 and COL4A3 genes.