Deletion of the HBB promoter leads to increased expression of HBG and increased HbF in CD34⁺ HSPCs. (A) HBB and HBG mRNA levels measured by qPCR in indicated sgRNA/s combination edited erythroid cells derived from CD34⁺ cells (n = 2) (mean plus or minus SEM). (B) Western blot analysis of γ-globin, β-globin, and α-globin and β-actin at day 15 differentiated erythroid cells derived from indicated sgRNA/s combination edited CD34⁺ cells. (C) Representative flow cytometric analysis of day 15 erythroid cells derived from indicated sgRNA/s combination edited CD34 cells stained with anti-HbF antibody. (D) Hemoglobin protein levels as determined by HPLC for day 15 erythroid cells derived from indicated sgRNA/s combination edited CD34⁺ cells. Peaks for each hemoglobin types or variants are indicated by the arrows above the peaks. SSC-A, flow cytometry side scatter.