Using a panel of FcγR KO mice, we found that the absence of FcγR I led to reduced anemia induced by IgG autoantibodies in LDV-infected animals, and that merely the expression of FcγR I allowed for the development of anemia, although it was less severe compared to the disease induced in WT mice receiving the same autoantibody. The gene discussed is FCGR2A; the disease is anemia.