Impact of age and MLL status on EFS. Kaplan-Meier survival curves show the impact of infant age and MLL status on EFS. (A) Patients with MLL-R have significantly shorter EFS than those without rearrangements (MLL-G; P = .008, log-rank test; HR = 3.23). (B) MLL-AFF1 cases have a nearly identical outcome pattern to overall MLL-R (P = .010; HR = 3.26). (C) Younger infants (≤ 90 days old) compared with older infants (> 90 days old) have significantly worse EFS (P = .009, log-rank test; HR = 2.13). (D) Infants with MLL-G have the best EFS, whereas infants less than or equal to 90 days of age with MLL-R have the worst EFS. Note that 2 patients died within 7 days of diagnosis, and they were excluded from these analyses.