TitleIdentification of novel HPFH-like mutations by CRISPR base editing that elevate the expression of fetal hemoglobin.
Publication TypeJournal Article
Year of Publication2022
AuthorsRavi NSam, Wienert B, Wyman SK, Bell HWilliam, George A, Mahalingam G, Vu JT, Prasad K, Bandlamudi BPrasad, Devaraju N, Rajendiran V, Syedbasha N, Pai AAnand, Nakamura Y, Kurita R, Narayanasamy M, Balasubramanian P, Thangavel S, Marepally S, Velayudhan SR, Srivastava A, DeWitt MA, Crossley M, Corn JE, Mohankumar KM
Date Published2022 02 11
KeywordsAdenine, Anemia, Sickle Cell, beta-Globins, beta-Thalassemia, Cell Line, Clustered Regularly Interspaced Short Palindromic Repeats, CRISPR-Cas Systems, Cytosine, Fetal Hemoglobin, gamma-Globins, Gene Editing, Hematopoietic Stem Cells, Humans, Point Mutation, Promoter Regions, Genetic

Naturally occurring point mutations in the promoter switch hemoglobin synthesis from defective adult beta-globin to fetal gamma-globin in sickle cell patients with hereditary persistence of fetal hemoglobin (HPFH) and ameliorate the clinical severity. Inspired by this natural phenomenon, we tiled the highly homologous proximal promoters using adenine and cytosine base editors that avoid the generation of large deletions and identified novel regulatory regions including a cluster at the -123 region. Base editing at -123 and -124 bp of promoter induced fetal hemoglobin (HbF) to a higher level than disruption of well-known BCL11A binding site in erythroblasts derived from human CD34+ hematopoietic stem and progenitor cells (HSPC). We further demonstrated in vitro that the introduction of -123T > C and -124T > C HPFH-like mutations drives gamma-globin expression by creating a de novo binding site for KLF1. Overall, our findings shed light on so far unknown regulatory elements within the promoter and identified additional targets for therapeutic upregulation of fetal hemoglobin.

Alternate JournalElife
PubMed ID35147495
PubMed Central IDPMC8865852