Both CFHR3 and CFHR1, lacking the CFH N-terminus regulatory activity, were reported to compete with CFH for binding to C3b, and thus CFHR3 and CFHR1 deficiency may lead to enhanced CFH regulation [31], which may explain the protective effect of the CFHR3-1Δ deletion in AMD. Here, CFHR3 is linked to age-related macular degeneration.