IREB2 and microcytic anemia: Irp2 depletion causes the deficiency of cellular functional iron by decreasing transferrin receptor and increasing ferritin expression (Jeong et al., 2011), which compromise the heme biosynthesis and finally trigger microcytic anemia in mice (Cooperman et al., 2005; Galy et al., 2005) and in humans (Cooper et al., 2019; Costain et al., 2019).