Systemic deficiency of Irp2 in mice results in microcytic anemia, erythropoietic protoporphyria [11], neurodegeneration [12], and diabetes [13,14], which are clinically manifested by phenotypes of patients with bi-allelic loss-of-function variants in IREB2 [15]. Here, IREB2 is linked to erythropoietic protoporphyria.