Traditional pharmacogenetics and genomics are forerunners of genomic medicine that use genetic methods to better match patients with treatments. The focus is on genetic markers that correlate with treatment response or adverse effects. Unlike clinical trials, which emphasize homogeneity of outcomes, pharmacogenetic studies emphasize heterogeneity. As such, the goal is to maximize efficacy while minimizing adverse events. Genetic variation can affect how individuals handle medications in a variety of ways, ranging from absorption to toxicity, all in the context of other individual variables, such as treatment adherence [Fig. 2]. Despite this complexity, several pharmacogenetic success stories have emerged in recent years. A few are highlighted here to illustrate how genetics can help reduce toxicity and adverse events – traditional aims of pharmacogenomics – but also help identify subgroups of patients with distinct pathophysiology that may be uniquely responsive to particular medications.
