JAK2 and anemia: The red blood cell (RBC) characteristics were normal but with more pronounced signs of anemia in aged Jak2-R1063H group than in wt mice (Fig. 1G top) and analysis of 3- and 12-month-old heterozygous Jak2-R1063H animals (m/RH) showed an intermediate phenotype, further supporting a dosage-dependent impact of the mutation also on erythroid parameters (Fig. 1G bottom).