Natural regulatory mutations elevate the fetal globin gene via disruption of BCL11A or ZBTB7A binding

b-hemoglobinopathies such as sickle cell disease (SCD) and beta-thalassemia result from mutations in the adult HBB (beta-globin) gene. Reactivating the developmentally silenced fetal HBG1 and HBG2 (gamma-globin) genes is a therapeutic goal for treating SCD and beta-thalassemia(1). Some forms of hereditary persistence of fetal hemoglobin (HPFH), a rare benign condition in which individuals express the gamma-globin gene throughout adulthood, are caused by point mutations in the gamma-globin gene promoter at regions residing -115 and -200 bp upstream of the transcription start site. We found that the major fetal globin gene repressors BCL11A and ZBTB7A (also known as LRF) directly bound to the sites at -115 and -200 bp, respectively. Furthermore, introduction of naturally occurring HPFH-associated mutations into erythroid cells by CRISPR-Cas9 disrupted repressor binding and raised gamma-globin gene expression. These findings clarify how these HPFH-associated mutations operate and demonstrate that BCL11A and ZBTB7A are major direct repressors of the fetal globin gene.