library_construction_protocol: CD34+ cells were purified from human cord blood (Cord Blood Bank of Beijing) using the MACS MicroBead kit (Miltenyi Biotec, Bergisch Gladbach, Germany). The CUT&Tag assay was performed as previously described and followed the manufacturer's instructions for the kit (Vazyme, Nanjing, China). Briefly, 100,000 cells were freshly collected and captured using Concanavalin A (ConA) beads at room temperature. The cell/ConA beads complex was permeabilized and incubated with the primary antibody (at 1:100 dilution) overnight at 4 °C. The secondary antibody was added to the solution and incubated at room temperature for 1 h. The secondary antibody was washed off prior to adding pA/G-Tn5 to the cell suspension and then incubated at room temperature for 1 h. The adapters were then inserted into the Tn5-tagged genome using the TruPrep Tagment Buffer L (TTBL). The genomic DNA was extracted with DNA beads, and the tagged DNA fragments were amplified using the Next-Generation Sequencing (NGS) adapters with 16 cycles of PCR. The adaptor dimer was removed from the PCR products with DNA Clean Beads (Vazyme, Nanjing, China). The library was quantified before sequencing.