CR1 is involved in clearance of C3b/C4b-coated immune complexes and regulation of complement activation, and RBCs with low CR1 may be more susceptible to complement-mediated damage and increased clearance, which are mechanisms associated with severe malarial anaemia.29, 47, 48 Alternatively, Sl2 and McCb could be under selection through other diseases unrelated to malaria. The gene discussed is C4B; the disease is malaria.