While we observed delayed globin switching, prolonged γ-globin mRNA half-life, reticulocytosis and anemia in the embryonic circulation of Zcchc6 and Dis3l2 KO mice, these phenotypes were attenuated in post-weanling mice, when fetal erythropoiesis is fully extinguished in favor of adult patterns of red cell development. The gene discussed is TUT7; the disease is anemia.