BACKGROUND: The response to the anticoagulant drug warfarin is greatly affected 
by genetic polymorphisms in the VKORC1 and CYP2C9 genes. Genotyping these 
polymorphisms has been shown to be important in reducing the time of the trial 
and error process for finding the maintenance dose of warfarin thus reducing the 
risk of adverse effects of the drug.
METHOD: We developed a real-time isothermal DNA amplification system for 
genotyping three single nucleotide polymorphisms (SNPs) that influence warfarin 
response. For each SNP, real-time isothermal Helicase Dependent Amplification 
(HDA) reactions were performed to amplify a DNA fragment containing the SNP. 
Amplicons were detected by fluorescently labeled allele specific probes during 
real-time HDA amplification.
RESULTS: Fifty clinical samples were analyzed by the HDA-based method, 
generating a total of 150 results. Of these, 148 were consistent between the 
HDA-based assays and a reference method. The two samples with unresolved 
HDA-based test results were repeated and found to be consistent with the 
reference method.
CONCLUSION: The HDA-based assays demonstrated a clinically acceptable 
performance for genotyping the VKORC1 -1639G>A SNP and two SNPs (430C>T and 
1075A>C) for the CYP2C9 enzyme (CYP2C9*2 and CYP2C9*3), all of which are 
relevant in warfarin pharmacogenentics.