Although there are no authentic repeats in this antigen, there are a number of internal homologies (N-A-N-P) and (N-A-D-P), the first of these tetramers is the dominant repeat found in the CSP of P.falciparum and reacts with antibodies against CRA. It is possible that immune responses to CRA may act against the CSP also. The CRA is found in many parasitic strains.