It seems that in contrast to mice with genetic IRP1 ablation [21–23], in Sod1-/- mice showing only partial decline in renal IRP1, regulatory axis IRP1-HIF2α and its impact on erythropoiesis and the occurrence of polycythemia are not altered as attested by normal peripheral erythrocyte count [16]. This evidence concerns the gene ACO1 and polycythemia.