Novel mutations in COL4A3, COL4A4, and COL4A5 in Chinese patients with Alport Syndrome

Abstract

Alport syndrome (AS) is a clinically and genetically heterogeneous, progressive nephropathy caused by mutations in , , and , which encode type IV collagen. The large sizes of these genes and the absence of mutation hot spots have complicated mutational analysis by routine polymerase chain reaction (PCR)-based approaches. Here, in order to design a rapid and effective method for the genetic diagnosis of AS, we developed a strategy by utilizing targeted capture associated with next-generation sequencing (NGS) to analyze , , and simultaneously in 20 AS patients. All the coding exons and flanking sequences of , , and from the probands were captured followed by HiSeq 2500 sequencing. Candidate mutations were validated by classic Sanger sequencing and quantitative (q)PCR. Sixteen patients (16/20, 75%) showed X-linked inheritance, and four patients (4/20, 20%) showed autosomal recessive inheritance. None of the individuals had autosomal-dominant AS. Fifteen novel mutations, 6 known mutations, and 2 novel fragment deletions were detected by targeted capture and NGS. Of these novel mutations, 12, 3, and 2 mutations were detected in , , and , respectively. A comparison of the clinical manifestations caused by different types of mutations in suggested that nonsense mutations and glycine substitution by an acidic amino acid are more severe than the other missense mutations. Pathogenic mutations were detected in 20 patients. These novel mutations can expand the genotypic spectrum of AS. Our results demonstrated that targeted capture and NGS technology are effective in the genetic diagnosis of AS.

The<b><i> COL4A3</i></b> and <b><i>COL4A4</i></b> Digenic Mutations in cis Result in Benign Familial Hematuria in a Large Chinese Family

“…Targeted capture and NGS was performed on a Hiseq2500 platform (Illumina) by BGI (Tianjin, China) as previously reported [Liu et al, 2017]. The gene panel (NimbleGen, Roche) contains 78 genes (associated with genetic kidney disease including AS, BFH, polycystic kidney disease, and steroid-resistant nephrotic syndrome) and was designed to capture coding regions, splice sites, and the immediately adjacent intronic sequences.…”

Reassessing the pathogenicity of c.2858G>T(p.(G953V)) in COL4A5 Gene: report of 19 Chinese families

“…However, many variants have quite limited evidence for pathogenicity assessment. With the wide application of next generation sequencing (NGS), more and more variations in COL4A5 gene are found and the relationship of genotype and phenotype are analyzed [15,16]. Therefore, the assessments of pathogenicity are important and would be corrected over time.…”

“…Both of the two variants in COL4A5 gene in five probands (except proband 9) were inherited from their mothers. It was proved the pathogenic variant c.937-2A>C in proband 9 was de novo, and the c.2858G>T(p.(G953V)) variant was inherited from her mother.Group 3: families with only the c.2858G>T(p.(G953V)) variantThere were six families in group 3 (family number[14][15][16][17][18][19]. Three of the probands in this group presented with steroid resistant nephrotic syndrome.…”

Three Novel Heterozygous<b><i> COL4A4</i></b> Mutations Result in Three Different Collagen Type IV Kidney Disease Phenotypes

“…In patients with ADAS, typical pathological changes of GBM include lamellation, splitting, thinning, or thickening [Kruegel et al, 2013;Liu et al, 2017]. However, TBMN is characterized by diffuse thin basement membrane changes [Savige et al, 2001].…”