HBA2 deletion and β^AS3integration efficiency in HSPCs. (A) Schematic representation of HSPC targeting experiments. (B) Editing efficiencies in HSPCs at day 12 of erythroid differentiation. Lines represent mean. HBA2 copies (C) and KI efficiency (D) in edited HSPCs in erythroid liquid culture (●) or in BFU-E (■). Black lines represent mean; red line indicates the number of expected HBA2 alleles in untreated HSPCs. (E) β^AS3 and glycophorin A (GYPA) transcripts in HSPC-derived erythroblasts (qPCR, n = 2, mean ± SD). (F) Relative abundance of endogenous β and KI-β^AS3 mRNA at day 12 of erythroid liquid culture (n = 6, mean ± SD). HBA2 deletion (G) and β^AS3 integration (H) pattern in single BFU-E. Bars represent mean ± SD (colonies derived from 2 independent experiments); no integration (0), monoallelic (1), and biallelic (2) KI or deletion (del). (I) Genotypes distribution of single KI-β^AS3 BFU-E. Percentages are indicated (n = 58).