This lack of knowledge is attributed in part to the multivalent weak affinities of FH for its ligands, which makes experimental studies difficult.30,31 A hallmark of early AMD is the appearance and growth of subretinal pigment epithelial deposits (sRPEds) that develop within Bruch's membrane, an extracellular matrix layer interposed between the retinal pigment epithelium (RPE) and the choroidal vasculature.32–34 sRPEds contain oxidised lipids, carbohydrates, cellular materials, and over 140 aggregated proteins including FH and other complement components. This evidence concerns the gene FH and age-related macular degeneration.