TPMT and acute lymphoblastic leukemia: Interestingly, in the discovery cohort, the effects of TPMT, SLCO1B1 and PACSIN2 polymorphisms were independent from each other, both in a multivariate logistic regression model and in a classification and regression tree analysis and could be combined in a multilocus genotype of potential importance to predict the incidence of severe mucositis in children with ALL treated with consolidation therapy comprising the combination of methotrexate and mercaptopurine (Figure 1).