RUNX1 and acute myeloid leukemia: To determine the relationship between transcriptional activity and chromatin loops involving the posterior HOXA genes, we performed in situ Hi-C on primary AML samples with the NPM1c mutation and with high HOXA expression (AML 507202) and a sample with the RUNX1-RUNX1T1 gene fusion and low HOXA gene expression (AML 275786; Fig. S1A).