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). The gene discussed is RUNX1T1; the disease is acute myeloid leukemia.