COL4A5 and kidney failure: In 2000, a study found among 401 male patients belonging to 195 families with pathogenic variants in COL4A5 , large deletions, nonsense variants, or small variants changing the reading frame conferred to affected patients a 90% probability of developing kidney failure before the age of 30 years, whereas the same risk was of 50% and 70% in patients with missense or splice site variants, respectively.3