ANSWER: Alport syndrome is a genetic disorder characterized by glomerulonephritis, end-stage kidney disease, hearing loss and, in some cases, progressive deterioration of vision. It is caused by mutations in the collagen synthesis genes COL4A3, COL4A4 and COL4A5. The mutations prevent the production or assembly of type IV collagen fibers, which are an important component of basement membranes, which separate and support cells in many tissues, including the kidney, inner ear and eye.