RUNX1 and acute lymphoblastic leukemia: All 14 unusual iAMP21‐ALL cases described in this study would not have been classified as iAMP21‐ALL based only on FISH data alone either because the RUNX1 FISH signals were located on other chromosomes besides chromosome 21 or they did not have the required greater than or equal to three additional RUNX1 signals on a single abnormal chromosome 21.