Human iPSCs-based modeling unveils chromatin remodeling induced by SETBP1 mutation as a potential initiating factor in GATA2 deficiency.

Patients with GATA2 deficiency are predisposed to developing myelodysplastic syndrome (MDS), which can progress to acute myeloid leukemia (AML). This progression is often associated with the acquisition of additional cytogenetic and somatic alterations. Mutations in SETBP1 and ASXL1 genes are frequently observed in pediatric GATA2 patients, but their roles in disease progression remain poorly understood. Genome editing of induced pluripotent stem cells (iPSCs) enabled precise reconstruction of mutation combinations found in patients. Here we developed a human hiPSC-based model to study the impact of SETBP1 and ASXL1 mutations in context of GATA2 deficiency. We show that germline heterozygous GATA2 mutation alone showed no significant effect on myeloid development, while the addition of SETBP1 and ASXL1 mutations impaired myelopoiesis, resulting in monocytopenia. We identified a key role of the SETBP1 mutation in promoting chromatin remodeling near genes involved in myeloid neoplasms, which likely initiated the blockage of myeloid differentiation observed in vitro. Motif analysis of more accessible chromatin regions in the SETBP1 and SETBP1/ASXL1 mutant background highlighted an enrichment for MEIS1, PU.1, RUNX1, and HOXA9, implicating these factors in the disease progression. Our study establishes a novel humanized model system for studying GATA2 deficiency. We demonstrate that SETBP1 mutations act as a primary driver in hematopoietic impairment, providing insights that may inform future therapeutic strategies for patients progressing to MDS/AML.