C3 and age-related macular degeneration: Smoking habits and diet are well established AMD risk factors, and various genetic predispositions are also associated with the risk of developing AMD including common AMD-related variants in or near genes C2/CFB, C3, C9, CFH, CFI, ARMS2 and VTN and various rare variants in genes CFH, CFI, C3, C9 and TIMP3.