An Expiration Date for Pharmacogenetic Test Results and Prescribing Guidance?

Abstract

The mother of Bob, an 18-year-old student headed to college, calls the clinical laboratory requesting pharmacogenetics test results and the “traffic-light” drug guidance table from 12 years ago. As a boy, Bob had been treated by a child psychiatrist for autism spectrum disorder and anxiety. She was told these results were good for life. Now a young adult, Bob has a new psychiatrist who wishes to have this information for personalized treatment. How should the clinical laboratory respond to the request? In this real-world situation, a fundamental question arises: Should pharmacogenetic test results and decision support bear an expiration date? Advances in molecular diagnostics, deeper sampling of diverse populations, new drugs, and evolving guidance from learned societies all point to the need for a term of use. The default “Normal” or “Functional” status in pharmacogenetic testing is defined as the absence of variants, and such default status is potentially iatrogenic. The omission of rare/ethnic-specific genetic variants with different effect sizes and allele frequency distribution across different populations can exacerbate the problem. At the same time, the resolution of pharmacogenetic tests has improved with advances in diagnostics technology (e.g., next-generation sequencing, sampling longer tracks of a given locus).