Global recombination of our Hba1 conditional allele (Hba1fl/fl; Sox2-Cre19), hereafter referred to as global Hba1Δ/Δ, (Supplementary Fig. 7a–c) produced an anemia phenotype that mirrors the global loss of Hba1 through the insertion of a neomycin resistance cassette20 (Supplementary Fig. 7d–f) with significant defects in blood hemoglobin and hematocrit but with no statistically significant change in total RBCs. This evidence concerns the gene SOX2 and anemia (phenotype).