C3 and age-related macular degeneration: For example, variants in the complement gene regions, such as the complement factor H (CFH) gene [111,112,113], complement component 2 and factor B (C2/CFB) gene [114], complement factor I (CFI) [112], and complement component 3 (C3) gene [112,115], are found to be associated with the pathogenesis of AMD.