Complement dysregulation caused by a complement factor H (FH) mutation, which was known to lead to membranoproliferative glomerulonephritis (often referred to as dense deposit disease),20 had also been implicated in AMD pathology, as affected individuals present with retinal drusen.21 In addition, a number of histochemical studies sought to analyze the changes that occurred within drusen of affected retinas22; crucially, a role for complement activation was highlighted. This evidence concerns the gene CFH and age-related macular degeneration.