Among these genes COL4A3 exhibits an extremely interesting genetic “behavior.” It is known that COL4A3 rare pathogenic variants are implicated in monogenic nephropathies such as Alport syndrome and thin basement membrane disease, however a common missense genetic variant of COL4A3 (rs55703767) has been identified recently in patients with DM type 1 displaying a protective role against the occurrence of diabetic kidney disease [44]. This evidence concerns the gene COL4A3 and Alport syndrome.