CFI and age-related macular degeneration: The complement pathway, which includes CFH (Complement Factor H), CFI (Complement Factor I), C2 (Complement Component 2), CFB (Complement Component Factor B), and C3 (Complement Component 3), accounts for a large proportion of these loci, as well as (to a lesser extent) the age-related maculopathy susceptibility (ARMS2) locus, which acts through a matrix metalloproteinase inhibitor.