The MFIs of CD59 and CD35 on RBCs from SLE patients were significantly reduced when compared to healthy controls, but this deficiency does not seem to be associated with anemia or autoimmune hemolytic anemia (AIHA), since the nonanemic and patients with no secondary AIHA also demonstrated reduced CD59 and CD35 MFI on their red cells. This evidence concerns the gene CR1 and systemic lupus erythematosus.