In contrast to Irp2-/- mice that develop microcytic hypochromic anemia with hematocrits of about 36%, adult Irp1-/- mice produce more RBCs than wild type animals (hematocrit ~50 vs. ~45%, Irp1-/- vs. wild type; Cooperman et al., 2005; Ghosh et al., 2013). Here, ACO1 is linked to anemia (phenotype).