RUNX1 and acute lymphoblastic leukemia: However, in three (7%) cases, the total number of RUNX1 signals could not be accurately quantified due to their large number of RUNX1 signals (>10) per cell; thus, these cases were indicated simply as “RUNX1 amplification.” The average maximum number and range of RUNX1 signals by interphase FISH were significantly higher in cases with typical iAMP21‐ALL compared to unusual iAMP21‐ALL (typical: average 6.2, range 5–10, unusual: median 4.8, range 3–8) (p < 0.0034) (Figure 1B, C).