Recommendations for Clinical Warfarin Genotyping Allele Selection: A Report of the Association for Molecular Pathology and the College of American Pathologists

J Mol Diagn. 2020 Jul;22(7):847-859. doi: 10.1016/j.jmoldx.2020.04.204. Epub 2020 May 4.


The goal of the Association for Molecular Pathology (AMP) Clinical Practice Committee's AMP Pharmacogenomics (PGx) Working Group is to define the key attributes of PGx alleles recommended for clinical testing and a minimum set of variants that should be included in clinical PGx genotyping assays. This document series provides recommendations for a minimum panel of variant alleles (tier 1) and an extended panel of variant alleles (tier 2) that will aid clinical laboratories when designing assays for PGx testing. The AMP PGx Working Group considered functional impact of the variants, allele frequencies in multiethnic populations, the availability of reference materials, as well as other technical considerations for PGx testing when developing these recommendations. The ultimate goal is to promote standardization of PGx gene/allele testing across clinical laboratories. These recommendations are not to be interpreted as prescriptive but to provide a reference guide. Of note, a separate article with recommendations for CYP2C9 allele selection was previously developed by the PGx Working Group that can be applied broadly to CYP2C9-related medications. The warfarin allele recommendations in this report incorporate the previous CYP2C9 allele recommendations and additional genes and alleles that are specific to warfarin testing.

Publication types

  • Practice Guideline
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles*
  • Anticoagulants / administration & dosage*
  • Cytochrome P-450 CYP2C9 / genetics*
  • Dose-Response Relationship, Drug
  • Drug Resistance / genetics
  • Gene Frequency
  • Genetic Testing / methods
  • Genotype*
  • Genotyping Techniques / methods*
  • Humans
  • Polymorphism, Single Nucleotide
  • Precision Medicine / methods
  • Research Report
  • Vitamin K Epoxide Reductases / genetics*
  • Warfarin / administration & dosage*


  • Anticoagulants
  • Warfarin
  • CYP2C9 protein, human
  • Cytochrome P-450 CYP2C9
  • VKORC1 protein, human
  • Vitamin K Epoxide Reductases