Frequently Asked Questions2016-12-20T19:16:44+00:00

Frequently Asked Questions

Questions about the Warfarin Sensitivity Genotyping (CYP2C9, VKORC1, CYP4F2, GGCX) DNA Test

Find out if you are at risk - get tested

Test Type Testing Time Fee

All orders received before 3pm PST / 6pm EST are shipped out the same business day. All orders received after 3pm PST / 6pm EST or on weekends or holidays are shipped out the following business day. 24/7 online status check and account management available for all tests.

How do I use
After receiving your genetic results, the results can be interpreted at To proceed, go to 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.
What is
The 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). is an independent website and is not under the control of our laboratory. The algorithm provided by 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
What specific information will I receive after taking the Warfarin genetic test?2016-12-20T19:06:31+00:00
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 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).
What genetic variations affect my Warfarin dosing level?2016-12-20T19:06:31+00:00
Genetic variations in CYP2C9, VKORC1, GGCX and CYP4F2 all affect the warfarin dose required to achieve a stable INR.
What are the dangers of improper Warfarin dosing?2016-12-20T19:06:32+00:00
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).
What is Warfarin?2016-12-20T19:06:32+00:00
A common anticoagulant drug prescribed to prevent the formation of blood clots (thrombosis) and their migration elsewhere in the body (thromboembolism).
How do I receive my results?2016-12-20T19:06:32+00:00
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.
Are my results confidential?2016-12-20T19:06:32+00:00
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.
How long do I have to send the samples back?2016-12-20T19:06:32+00:00
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.
Can I have more than one copy of the results?2016-12-20T19:06:32+00:00
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.
Is there an age limit?2016-12-20T19:06:32+00:00
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.
Which countries can you ship to?2016-12-20T19:06:32+00:00
The DNA collection kits can be shipped to any country in the world.
How long will testing take?2016-12-20T19:06:32+00:00
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.