C2 and age-related macular degeneration: As one result, non-synonymous variants in five genomic loci point towards an involvement of the complement cascade as part of the innate immunity system4–6, implicating genes such as complement component 2 (C2), 3 (C3), 4 (C4), 9 (C9) as well as complement factor H (CFH), I (CFI), and B (CFB) in AMD pathology.