Figure 1.

Clinical validity of testing—the probabilistic nature of pharmacogenomics. Although pharmacogenomic test results will enable health professionals to predict drug response better, individual patients may still react in an unpredictable manner. Following testing, individuals classified as responders, for example, are likely to respond to a prescribed drug (far right), but may (rarely but significantly) be non-responders (middle area of overlap). Similarly, individuals classified as non-responders will probably not respond to a prescribed drug (far left), but may (rarely but significantly) be responders (middle area of overlap). A comparable situation will exist for the overlap between responders and patients predicted to experience adverse reactions. Adapted from reference 12