RUNX1 and acute lymphoblastic leukemia: Of these 14 unusual iAMP21‐ALL cases, 7 (50%) cases (patients 2, 3, 7, 9, 10, 11, and 14) had fewer than 5 total RUNX1 signals per cell by interphase FISH (“Category 1”) (Figure 1D, E, Tables 1 and 2).