Overview
Pharmacogenomic tests identify germline alleles that alter drug metabolism, transport, or immune-mediated adverse reaction risk.
Clinical Importance
Guide therapy for drugs with actionable PGx associations
Reduce risk of severe toxicity (e.g., HLA-B*57:01 and abacavir pathways)
Specimen Requirements
- Specimen: whole blood or plasma as validated for the assay
- Tube: lavender-top K₂EDTA (preferred for many viral load and germline DNA assays)
- Handling: mix gently; separate plasma promptly when required; avoid heparin for many PCR assays (inhibition)
- Storage: refrigerate or freeze plasma per IFU; extract nucleic acid within validated windows
Analytical Method
Targeted genotyping (PCR, arrays, or NGS panels) detects star-allele defining variants. Diplotypes are translated to predicted phenotypes (e.g., poor metabolizer). Clinical implementation follows CPIC or similar guidelines adopted locally; the laboratory reports genotype/phenotype, not the final prescription.
Instruments Used
Automated analyzers
- Applied Biosystems / Thermo Fisher real-time PCR systems (e.g., QuantStudio-class)
- Roche Cobas molecular / LightCycler systems
- Cepheid GeneXpert cartridge PCR systems
- BioFire FilmArray syndromic PCR systems
- Abbott m2000 / Alinity m molecular systems
- Hologic Panther / Aptima molecular systems
- Illumina next-generation sequencing platforms
- Thermo Fisher Ion Torrent sequencing platforms
- Digital PCR systems (e.g., Bio-Rad QX / QIAGEN QIAcuity-class)
- Sanger capillary electrophoresis sequencers (Applied Biosystems)
Manual methods
- Manual nucleic acid extraction, PCR setup, and gel/capillary analysis in selected workflows
Reference Values
Molecular cutoffs, units (IU/mL, copies/mL, Ct), reportable ranges, and variant classifications are assay- and laboratory-specific. Always interpret against the performing laboratory report, manufacturer IFU, and current CLSI / CAP / AMP / ACMG guidance as adopted locally. Limit of detection and inhibition controls are essential for negative results.
No traditional reference interval. Results are diplotype + predicted phenotype. Copy-number (e.g., CYP2D6) may be required for accurate phenotype.
Interpretation
Common Causes of Increased Results
- Alleles predicting increased activity or increased ADR risk; apply drug-specific guidance
Common Causes of Decreased Results
- Alleles predicting reduced/absent function; may require dose reduction or alternate therapy per guidelines
Clinical Significance
- Preemptive or reactive PGx panels
- Drug-specific single-gene tests
Factors Affecting Results
Pre-analytical
- Wrong specimen type or transport medium for the validated assay
- Delayed transport degrading RNA targets
- Contamination during collection (especially amplicon-rich environments)
- Inadequate volume or low cellularity/tumor content
Analytical
- Incomplete allele coverage misassigning star alleles
- Missing CYP2D6 CNV analysis when needed
Post-analytical
- Equating genotype with a mandatory prescription change without clinical context
Advantages and Limitations
Advantages
- Actionable for selected high-evidence drug–gene pairs
Limitations
- Not all drugs have PGx guidance
- Ancestry-specific alleles may be underrepresented on panels
Clinical Pearls
PGx predicts risk and metabolism; the clinician still owns the prescription pad.
References
Authoritative textbooks, guidelines, and reviews supporting this laboratory test reference. Verify reference intervals, critical limits, and method details against institutional protocols and current guideline editions.
Textbooks
- McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2021. (Molecular diagnostics chapters, verify current edition.)
- Buckingham L. Molecular Diagnostics: Fundamentals, Methods, and Clinical Applications. 3rd ed. F.A. Davis; 2019. (Verify current edition and institutional adoption.)
CLSI and Professional Guidelines
- Clinical and Laboratory Standards Institute (CLSI). Consult current CLSI molecular method documents available through your laboratory, document numbers and editions change; do not treat any single CLSI title as universal.
- Institutional molecular laboratory standard operating procedures (SOPs), assay manufacturer instructions for use (IFU), and locally adopted accreditation requirements. Always verify current local practice.
- Clinical and Laboratory Standards Institute (CLSI). Molecular method evaluation and related documents (verify current CLSI editions applicable to the assay).
- College of American Pathologists. Molecular pathology accreditation and proficiency testing expectations (verify current CAP checklist requirements).
- Association for Molecular Pathology (AMP). Practice guidelines and position statements for molecular diagnostics (verify current AMP documents for the assay).
- American College of Medical Genetics and Genomics (ACMG). Standards and guidelines for interpretation of sequence variants and related genetic testing practice (verify current ACMG documents).
WHO Publications
- World Health Organization. Laboratory and diagnostic guidance relevant to molecular testing (verify current WHO publication for the assay/pathogen).
Frequently Asked Questions
Common questions about using this Pharmacogenomic Testing laboratory test Medical Laboratory Library reference in Medical Laboratory Science education.
What is the Pharmacogenomic Testing laboratory test reference used for?
This Medical Laboratory Library page summarizes the clinical importance of Pharmacogenomic Testing. Review the Clinical Importance section for why the test is ordered in laboratory medicine practice.
Where can I find Pharmacogenomic Testing specimen requirements?
See the Specimen Requirements section on this page for specimen information related to Pharmacogenomic Testing. Confirm collection details against your laboratory protocol.
Where are Pharmacogenomic Testing reference values listed?
See the Reference Values section on this Laboratory Library page. Reference ranges can vary by method and population, so verify intervals with your laboratory.
How do I interpret Pharmacogenomic Testing results?
Use the Interpretation section for laboratory interpretation framing, including increased and decreased result patterns when provided. Do not treat educational text as a patient-specific diagnosis.
What analytical method is used for Pharmacogenomic Testing?
See the Analytical Method section for principle and method notes. Method details may differ by instrument and institutional SOP.
Are related laboratory tests linked from Pharmacogenomic Testing?
Yes. The Related Laboratory Tests section lists connected references for continued lookup in the Medical Laboratory Library.
How can I continue learning after reading Pharmacogenomic Testing?
Use Continue learning links on this page for related Academy lessons, medical laboratory quizzes, or laboratory case studies when available for this Molecular Diagnostics topic.
What are the clinical pearls for Pharmacogenomic Testing?
See the Clinical Pearls section for concise laboratory practice notes associated with Pharmacogenomic Testing. Apply pearls alongside institutional protocols.
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