Genes significantly associated with minimal residual disease (MRD) on day 19 and with leukemic relapse. Among the 674 probe sets that were significantly associated with MRD on day 19 in 187 patients (P < .006), 44 were significantly associated with leukemic relapse (P < .03) in an independent cohort of 99 patients, regardless of whether they were analyzed as a continuous or categoric variable. Bars indicate the fold increase/decrease in hazard per unit increase in expression of each gene, calculated with the proportional hazards regression model.²⁶  Black bars correspond to genes that were independent predictors of outcome after adjustment for known prognostic features of childhood acute lymphoblastic leukemia (ALL).