In the case of MSP1, a proportion of anti-MSP1 antibodies called “blocking” antibodies, which are found in people living in malaria endemic areas, competes with an anti-MSP1 monoclonal antibody capable of inhibiting merozoite invasion of erythrocytes in vitro, as judged by a competition ELISA and by an MSP1 processing assay [37]–[39]. The gene discussed is ATAD1; the disease is malaria.