DHCR7-DT and age-related macular degeneration: Common variants in genes encoding the AP components C3 and FB and the AP regulator FH are individually associated with higher C3 convertase activity and increased AMD risk; a combination of risk variants in these three genes (C3 (rs2230199), CFB (rs641153), and CFH (rs800292)) increased complement activity in plasma six-fold [12].