Frequently Asked Questions

After receiving your genetic results, the results can be interpreted at www.warfarindosing.org. To proceed, go to www.warfarindosing.org and enter the following patient information is in the corresponding boxes: Age, sex, ethnicity, race, weight, height, smoking status, presence or absence of liver disease, indication, baseline international normalized ratio (INR), target INR and current medications. The genetic information is entered by selecting the matching result from the dropdown boxes for the following SNPs: VKORC1 -1639G>A = VKORC1-1639/3673 CYP4F2 1297C>T = CYP4F2 V433M GGCX 12970C>G = GGCX rs11676382 CYP2C9 430C>T = CYP2C9*2 CYP2C9 1075A>C = CYP2C9*3 CYP2C9 1080C>G = CYP2C9*5 CYP2C9 818delA = CYP2C9*6 (select ‘A- (heterozygous)’ for an ‘AG’ result or ‘– (homozygous mutant)’ for a ‘GG’ result) The algorithm calculates an initial warfarin dose requirement and an estimated daily warfarin dose requirement, in order to achieve the target INR.

The WarfarinDosing.org website is provided by the Warfarin Dose Refinement (DR) Collaboration and IWPC (a group of international collaborations of biostatisticians, geneticists, pharmacists, and physicians who share anonymous data to improve warfarin dosing). WarfarinDosing.org is an independent website and is not under the control of our laboratory. The algorithm provided by WarfarinDosing.org is continually updated to ensure it provides an accurate and safe warfarin dose estimate. However, our laboratory holds no responsibility for the content and availability of WarfarinDosing.org.

A genotype will be provided for each of the 11 SNPs tested in this analysis. The genotypes will indicate whether the individual has the homozygous wild type, heterozygous or homozygous variant/mutant allele at each position. This information is entered into the WarfarinDosing.org algorithm, which calculates an initial warfarin dose requirement and an estimated daily warfarin dose requirement, in order to achieve the target international normalized ratio (INR).

Genetic variations in CYP2C9, VKORC1, GGCX and CYP4F2 all affect the warfarin dose required to achieve a stable INR.

If the dose is too high, there is an increased risk of abnormal bleeding (hemorrhage). If the dose is too low, it indicates that it is insufficient to protect against blood clots (thrombosis).

A common anticoagulant drug prescribed to prevent the formation of blood clots (thrombosis) and their migration elsewhere in the body (thromboembolism).

You can choose to receive your results report by mail, email or both. The test includes one copy of the results by mail and one copy by email at no charge. The results report is issued immediately once the testing is completed.

Yes, your results are 100% confidential. No one will be able to access your account or your results unless you give them your confidential account login. You can change the password to your account at any time. Please remember to safeguard your login information and not share it with anyone.

The DNA testing kit does not have an expiry date so you can use the kit at any time. Once the DNA sample is collected, the sample should be returned to the laboratory for testing within 3 months of the collection date. The DNA sample will remain stable for 3 months at room temperature after collection.

If your sample contains intact DNA, then a full DNA profile will be obtained. However, if your sample does not contain DNA or contains degraded DNA, then only a partial profile or no profile at all is obtained. Even if no profile is obtained, the cost still applies for each sample that is submitted.

No, there is no age limit for Warfarin Sensitivity DNA Test testing. The test can be performed on individuals at any age, even newborns. The sample is collected easily and discretely using buccal swabs.

The DNA collection kits can be shipped to any country in the world.

DNA testing begins immediately the day that your samples arrive at the laboratory and is completed within 5 to 7 business days. In some special situations, additional testing may be required, which could increase the turnaround time by a few extra days. You can check the status of your test online 24/7 using your secure account login. Your test report is released immediately once testing is complete.