A novel missense mutation of COL4A5 gene alter collagen IV α5 chain to cause X-linked Alport syndrome in a Chinese family

Background: X-linked Alport syndrome (XLAS) is the most common form of Alport syndrome (AS), involves mutations in the COL4A5 gene encoding the type IV collagen a5 chain. In this research, we will report the analysis of the COL4A5 gene in a Chinese family with XLAS, and investigate the effect of the missense mutation of this family on type IV collagen. Methods: Targeted sequencing using next-generation sequencing (NGS) was conducted for genes (COL4A3/4/5). Normal and mutation COL4A5 plasmids were constructed and then transfected into human podocytes, none plasmid and empty plasmid transfection as control. And then real-time PCR, western blot and indirect immunofluorescence were used to detect the COL4A1/3/5 mRNA, protein, and immunofluorescence expression of each group. Results: In this study, we found an Alport family, and the whole exon sequencing found a new missense mutation c.1844G>C in exon 25. The results of real-time PCR, western blot and immunofluorescence showed that in the mutation group, both the mRNA and protein levels of COL4A5 were significantly reduced. Conclusions: c.1844G>C is a functional variation of COL4A5, which might play a very important role in the occurrence and development of AS.