While the remaining 7 unusual iAMP21‐ALL (50%) cases (patients 1, 4, 5, 6, 8, 12, and 13) had five or more RUNX1 signals per cell by interphase FISH, the additional RUNX1 signals were located apart from the abnormal iAMP21‐chromosome (“category 2”) (Figure 1D, F, Tables 1 and 2). Here, RUNX1 is linked to acute lymphoblastic leukemia.