Differences in Predicted Warfarin Dosing Requirements Between Hmong and East Asians Using Genotype-Based Dosing Algorithms

Boguang Sun, Ya Feng Wen, Kathleen A. Culhane-Pera, Muaj Lo, Txia Xiong, Koobmeej Lee, Kerui Peng, Bharat Thyagarajan, Jeffrey R. Bishop, Heather Zierhut, Robert J. Straka

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


INTRODUCTION: Warfarin's narrow therapeutic index and high variability in dosage requirements make dosage selection critical. Genetic factors are known to impact warfarin dosage selection. The Hmong are a unique Asian subpopulation numbering over 278,000 in the United States whose participation in genetics-based research is virtually nonexistent. The translational significance of early reports of warfarin pharmacogene differences in Hmong has not been evaluated.

OBJECTIVES: (i) To validate previously identified allele frequency differences relevant to warfarin dosing in Hmong versus East Asians and (ii) to compare predicted warfarin sensitivity and maintenance doses between a Hmong population and an East Asian cohort.

METHOD: DNA collected from two independent cohorts (n=236 and n=198) of Hmong adults were genotyped for CYP2C9 (*2, *3), VKORC1 (G-1639A), and CYP4F2 (*3). Allele frequencies between the combined Hmong cohort (n=433) and East Asians (n=1165) from the 2009 International Warfarin Pharmacogenetics Consortium (IWPC) study were compared using a χ 2 test. Percentages of Hmong and East Asian participants predicted to be very sensitive to warfarin were compared using a χ 2 test, and the predicted mean warfarin maintenance dose was compared with a t test.

RESULTS: The allele frequencies of CYP2C9*3 in the combined Hmong cohort and CYP4F2*3 in the VIP-Hmong cohort are significantly different from those in East Asians (18.9% vs 3.0%, p<0.001 and 9.8% vs 22.1%, p<0.001, respectively). Comparing the combined Hmong cohort to the East Asian cohort, the percentage of participants predicted to be very sensitive to warfarin was significantly higher (28% vs 5%, p<0.01) and the mean predicted warfarin maintenance dose was significantly lower (19.8 vs 21.3 mg/week, p<0.001), respectively.

CONCLUSION: The unique allele frequencies related to warfarin when combined with nongenetic factors observed in the Hmong translate into clinically relevant differences in predicted maintenance dose requirements for Hmong versus East Asians.

Original languageEnglish (US)
Pages (from-to)265-276
Number of pages12
Issue number3
StatePublished - Mar 2021

Bibliographical note

Funding Information:
The authors wish to thank the support from all the participants and the Hmong Genomic Board. Specifically, we appreciate Helene Barcelo‐Larson, PhD, and staff in University of Minnesota Molecular Diagnostics Laboratory and the Advanced Research and Diagnostics Laboratory for their invaluable assistance in genotyping.

Publisher Copyright:
© 2020 Pharmacotherapy Publications, Inc.


  • Asian Americans
  • anticoagulant drugs
  • minority health
  • pharmacogenetics
  • precision medicine
  • warfarin


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