RNA sequencing of CD19+ blasts showed enrichment of fetal myeloid programs18 and a composite stem cell gene set19 along with reduced expression of lymphoid programs18 in PROM1-high CRISPRKMT2A::AFF1 ALL (Figure 1E-G; supplemental Figure 1A-B; supplemental Table 3). This evidence concerns the gene AFF1 and acute lymphoblastic leukemia.