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Updated: Jul 25, 2026
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Candidate Gene Testing in Clinical Cohort Studies with Multiplexed Genotyping and Mass Spectrometry
Published on: June 21, 2018
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Comparison of targeted vs. expanded pharmacogenomic testing: What are we missing?
Journal of the American Pharmacists Association : Japha
|April 6, 2023
Summary
Expanded pharmacogenomics (PGx) testing identifies significantly more gene-drug interactions than targeted panels. Limited PGx testing risks missing crucial interactions, potentially leading to adverse events and ineffective treatments.
Area of Science:
- Pharmacogenomics
- Genetics
- Clinical Pharmacology
Background:
- Pharmacogenomics (PGx) is an emerging medication management strategy that tailors treatments to individual genetic profiles.
- Preventable adverse events linked to pharmacogenomic variations underscore the urgency of wider PGx implementation for patient safety.
- Genetic variations influence drug metabolism, transport, and efficacy, impacting treatment outcomes.
Purpose of the Study:
- To compare the comprehensiveness of targeted PGx testing (single gene-drug, dual gene, psychiatric panels) against expanded PGx panel testing.
- To quantify the divergence in identified gene-drug interactions between different PGx testing strategies.
Main Methods:
- An expanded PGx panel (≥25 genes) was used as a baseline for comparison.
- Targeted panels evaluated included a single gene-drug pair (CYP2C19/clopidogrel), a dual gene panel (CYP2C19/CYP2D6), and psychiatric panels (7-gene and 14-gene).
- The study assessed the proportion of known actionable gene-drug interactions identified by each testing approach.
Main Results:
- Expanded PGx testing identified all gene-drug interactions with Clinical Pharmacogenomics Implementation Consortium (CPIC) guidance or FDA labeling.
- Targeted testing missed a substantial percentage of interactions: CYP2C19/clopidogrel missed ~95%, CYP2C19/CYP2D6 missed ~89%, and a 14-gene panel missed ~73%.
- A 7-gene psychiatric list missed ~20% of potential interactions, as it was not designed for comprehensive interaction discovery.
Conclusions:
- Targeted PGx testing, focusing on limited genes or specific specialties, frequently fails to identify a significant proportion of actionable gene-drug interactions.
- This omission by targeted testing can result in patient harm due to missed interactions, leading to treatment failures and adverse drug reactions.
- Expanded PGx panels offer a more comprehensive assessment of genetic variations impacting drug response, enhancing proactive patient care and safety.
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