COL4A3 and kidney failure: Alport disease, which is a familial nephropathy marked by focal splitting, thinning, and regional thickening of the GBM and leads to renal failure, is caused by mutations in either the COL4A3, COL4A4, or COL4A5 genes encoding the collagen α3(IV), α4(IV), and α5(IV) protein chains, respectively [18], [19].