Proportions of patients preemptively genotyped at St. Jude Children’s Research Hospital with high-risk phenotypes. Data are from the PG4KDS clinical trial and are shown as of November 1, 2021. The study genotyped 5,912 patients for the following 13 pharmacogenes: CACNA1S, CYP2B6, CYP2C19, CYP2C9, CYP2D6, CYP3A5, DPYD, G6PD, mt-RNR1, RYR1, SLCO1B1, TPMT, and UGT1A1. Patients diagnosed with acute lymphoblastic leukemia were also genotyped for NUDT15. A high-risk phenotype is a result that has implications for the use of at least one medication.