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Pharmacogenomics aims to improve medication safety and dosing by incorporating the guidance of patients’ genetic information into treatment decisions. While pharmacogenomic (PGx) testing has become more widely available and less costly, its use in routine clinical care has lagged. Major barriers to implementation have included the difficulty of interpreting test results in practice and the need for clinician education and decision-making support. Over the past decade, organizations such as the Clinical Pharmacogenetic Implementation Consortium have addressed these barriers by evaluating the strength of evidence for the actionability of gene-drug associations.1 Evidence-based guidelines for the use of PGx information in treatment decisions are currently available for more than 35 genedrug pairs covering a wide range of medications, including oncologic agents and antidepressant and pain medications.1 However, guidelines do not provide recommendations on when to order PGx tests, and a major question in the field is whether these tests should be offered reactively, based on patient treatment and medical history, or preemptively. Cohn and colleagues2 address this question by reporting the outcomes of a pilot program combining reactive and preemptive approaches for PGx testing in a pediatric tertiary hospital. Two cohorts were offered PGx testing for a panel of 6 genes with high evidence of actionability, with the support of a PGx consultation for the interpretation of the findings. The first cohort was tested at the point of care using the reactive model, with patients identified based on their exposure to a PGx targeted drug as well as adverse reactions (including lack of therapeutic benefit) after receipt of a PGx targeted drug. The second cohort was tested using a preemptive approach, with patients recruited from a cardiac genome clinic independently of previous or planned exposure to a PGx targeted drug; preliminary information on PGx genotypes was extracted from genomic information, and substantial findings were confirmed using the 6-gene panel. Although a direct comparison of the outcomes between the 2 cohort approaches is not possible because of differences in the recruitment processes and underlying treatments, this study provides information on the use of 2 modes of PGx testing within a single institution. Overall, results were consistent with those of other studies that used either of the 2 approaches.3-5 In the point-of-care cohort, 40% of the patients with current or planned exposure to a PGx targeted drug were found to have a genotype warranting a change in treatment. In the preemptive cohort, treatment adjustment for at least 1 drug-gene association would apply to 80% of the children if they were to receive the medication. The authors complement this analysis of short-term outcomes with case summaries illustrating the context of PGx testing. They describe the type of drug responses that may have warranted testing for different drugs and the treatment adjustments made for patients with abnormal function in the associated gene. Altogether, this study provides valuable information on the real-world use of PGX test results and supports the clinical benefit of both the reactive and the preemptive modes of PGx testing implementation in pediatric care. Although the findings from Cohn and colleagues2 may be limited to pediatric populations in a specialized hospital comprising patients who often present with complex medical conditions, opportunities for PGx-guided treatment exist in the general pediatric population. An analysis of prescribing patterns in a study of 2.9 million pediatric patients across 16 US institutions found that the receipt of medications with high evidence of PGx actionability is common among pediatric patients.6 The PGx targeted drug classes most frequently prescribed to pediatric patients included + Related article