Comparison of assay systems for warfarin-related CYP2C9 and VKORC1 genotyping

BackgroundA variety of commercial genotyping assays is available to detect variants in the CYP2C9 and VKORC1 genes. The assay results are used in genotype-based warfarin dosing algorithms. We compared the performance of four such assay systems: Verigene®, eSensor®, Invader®, and Luminex®.MethodsResult concordance and no call rates were determined on patient specimens tested on all four instruments. Turnaround times (TAT), hands-on time (HOT), pipetting steps and cost were obtained for runs of 1, 8 and 24 samples.ResultsThe four assays were 100% concordant for the common CYP2C9 and VKORC1 alleles (n = 100). Verigene had the shortest TAT and HOT for 1 and 8 samples. Verigene had the fewest pipetting steps for all sample sizes, while Invader had the most. Luminex had the longest TAT and highest cost for all sample run sizes. Verigene had the lowest cost for 1 and 8 samples and Invader the lowest for 24 samples. The no call rates for Verigene, Luminex, eSensor, and Invader were 10%, 4%, 1% and 0%, respectively.ConclusionsAll assays gave comparable results for common variants. Each system offered unique advantages and disadvantages, whose relative importance depends on the needs of the adopting clinical laboratory.