Project Summary/ Abstract Our lab has made substantial strides in understanding how human genetic variation affects erythropoiesis and fetal hemoglobin (HbF) levels, both critical factors in conditions such as sickle cell disease and β-thalassemia, as well as other forms of anemia. Utilizing cutting-edge genetic studies, we have mapped thousands of genetic variants influencing red blood cell phenotypes and HbF levels. We have also functionalized these variants through the use of innovative techniques such as massively parallel reporter assays and base editing in primary human hematopoietic stem and progenitor cells that were developed with support we received over the past ten years from this grant. In this competitive renewal application for this foundational grant, “Systematic Genetic Dissection of Human Erythropoiesis,” we propose a deeper investigation into the genetic network regulating human erythropoiesis and HbF expression. Specifically, we aim to 1) use massively parallel base editing to pinpoint key nucleotide determinants of HbF-related regulatory elements; 2) chart high-resolution interaction maps between these regulatory elements, their target genes, and other interactive genomic elements across different stages of erythropoiesis; and 3) conduct multiplexed base editing of key transcription factors and identified regulatory nucleotides to understand their genetic interactions. Our research will provide invaluable insights into the intricate genetic mechanisms regulating erythropoiesis and HbF expression, potentially paving the way for innovative therapeutic approaches for hemoglobinopathies. This project signifies a critical foundational step in leveraging genetic knowledge for the development of clinical interventions in debilitating hematological conditions.