Pharmacogenomics and Precision Medicine: From GeneticTesting to Individualized Pharmacotherapy

Abstract

Pharmacogenomics (PGx) examines how inherited genetic variation influences drug exposure, efficacy, and toxicity. Genetic results can guide treatment when the gene-drug relationship is clinically valid, actionable, and interpreted in the context of the patient and the intended use. This narrative review summarizes the path from testing and genotype interpretation to individualized pharmacotherapy, highlighting implementation evidence, guideline resources, and barriers to equitable routine care. Established examples include HLA-B*57:01 testing to prevent abacavir hypersensitivity; TPMT and NUDT15-guided thiopurine dosing; CYP2C19-guided selection of antiplatelet therapy; DPYD-informed fluoropyrimidine dosing; and CYP2D6-guided use of codeine and tramadol. The FDA’s current pharmacogenetic association table distinguishes associations with therapeutic-management recommendations from those supported only by pharmacokinetic evidence, underscoring that a gene-drug association does not automatically justify testing. The PREPARE implementation trial reported fewer clinically relevant adverse drug reactions among patients with actionable gene-drug pairs receiving a pre-emptive 12-gene panel, while trials in specific settings show that clinical utility varies with population, comparator, outcome, and implementation. Testing alone is insufficient: assay coverage, phenotype translation, ancestry-related allele representation, drug interactions, clinical decision support, result portability, informed consent, and clinician education all influence benefit. PGx is most effective when integrated with medication review, clinical monitoring, patient preferences, and evidence-based guidelines, rather than treated as a stand-alone prescribing algorithm. Further pragmatic research should assess long-term outcomes, costs, equity, and workflow effects across diverse health systems.

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Khushi Malik. Pharmacogenomics and Precision Medicine: From GeneticTesting to Individualized Pharmacotherapy. ClinSphere Journals. 2026;undefined(undefined). https://doi.org/10.5281/zenodo.23803482

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