Therefore, we used sera from three different patients with clinically relevant CAD to further investigate the influence of IgM aab on donor RBCs under different conditions (temperature, titer, complement concentration) looking for signs of intravascular hemolysis (free hemoglobin), eryptosis (Annexin V-binding to externalized PS) and extravascular hemolysis (using C3d as a surrogate for C3b). The gene discussed is CD40LG; the disease is cold agglutinin disease.