An illustrative example of this situation was described by Caesar et al., who showed that FHR-3 competes with FH for the binding of a FH-binding protein on Neisseria meningitidis, acting as a FH antagonist, which explains why the CFH haplotype 3, characterized by low FH and high FHR-3 plasma levels, is associated with lower susceptibility to meningococcal disease (78, 80). This evidence concerns the gene FH and meningococcal infection.