The thrombotic risk DNA test looks at variants in three genes: F5, F2 and MTHFR. Below is a description of how to interpret your results for these individual genes.
Understanding Your Factor V Leiden Mutation Test Results
Thrombophilia is a condition where the blood has an increased tendency to form clots. The F5 gene encodes for Factor V – a protein that promotes blood clotting. When the 1691G>A mutation (known as Factor V Leiden) is present, the Factor V protein cannot be inactivated as efficiently as normal, leading to increased blood clotting and an increased risk of thrombophilia.
General Definitions:
Normal
A normal result means that the person has tested negative for the 1691G>A mutation in the F5gene and is not at increased risk of developing thrombophilia. This person will not pass a defective F5 gene to the next generation.
Heterozygous Affected
A heterozygous affected individual has inherited one defective F5 gene and one normal wild type F5 gene. Heterozygous affected individuals have a 3- to 8-fold increased risk of thrombophilia and have a 50% chance of passing the defective gene to future generations. If two heterozygous affected individuals have children, there is a 25% chance that their children will be normal, a 50% chance that their children will also be heterozygous affected, and a 25% chance that their children will inherit two defective genes and be at an even higher risk of developing thrombophilia.
Homozygous Affected
A homozygous affected individual has inherited two copies of the defective F5 gene containing the 1691G>A mutation, one defective gene from each parent. Although people with two defective genes have a significantly higher risk (greater than 10-fold) of developing thrombophilia, not everyone with two copies of the defective F5 gene has blood clotting abnormalities. There is a 100% chance that an affected individual with a homozygous genotype will pass the defective F5 gene to their children.
Understanding Your F2 Prothrombin Mutation Test Results
Thrombophilia is a condition where the blood has an increased tendency to form clots. The F2 gene encodes for prothrombin – a protein that promotes blood clotting. When the 20210G>A mutation is present, too much prothrombin protein is produced, leading to increased blood clotting and an increased risk of thrombophilia.
General Definitions:
Normal
A normal result means that the person has tested negative for the 20210G>A mutation in the F2 gene and is not at increased risk of developing thrombophilia. This person will not pass a defective F2 gene to the next generation.
Heterozygous Affected
A heterozygous affected individual has inherited one defective F2 gene and one normal wild type F2 gene. Heterozygous affected individuals have a 2- to 5-fold increased risk of thrombophilia and have a 50% chance of passing the defective gene to future generations. If two heterozygous affected individuals have children, there is a 25% chance that their children will be normal, a 50% chance that their children will also be heterozygous affected, and a 25% chance that their children will inherit two defective genes and be at an even higher risk of developing thrombophilia.
Homozygous Affected
A homozygous affected individual has inherited two copies of the defective F2 gene containing the 20210G>A mutation, one defective gene from each parent. Although people with two defective genes have a significantly higher risk of developing thrombophilia, not everyone with two copies of the defective F2 gene has blood clotting abnormalities. There is a 100% chance that an affected individual with a homozygous genotype will pass the defective F2 gene to their children.
Understanding Your MTHFR Test Results
Thrombophilia is a condition where the blood has an increased tendency to form clots. The MTHFR gene encodes for methylenetetrahydrofolate reductase – a protein that helps process Vitamin B9 (folate). When the MTHFR gene contains a mutation, Vitamin B9 is not as efficient at converting homocysteine to methionine and an excess of homocysteine accumulates. High homocysteine levels can increase the risk of thrombophilia.
General Definitions:
Normal
A normal result means that the person has tested negative for the 677C>T and 1298A>C mutations in the MTHFR gene and is not at increased risk of thrombophilia. This person will not pass a defective MTHFR gene to the next generation.
Carrier
A carrier is an individual who has inherited one defective MTHFR gene and one normal wild type MTHFR gene. Carriers have a 50% chance of passing the defective gene to future generations but usually do not have an increased thrombophilia risk themselves. If two carriers have children, there is a 25% chance that their children will be normal, a 50% chance that their children will also be carriers, and a 25% chance that their children will inherit two defective genes and be at risk of thrombophilia.
Affected
An affected individual is one who has inherited two copies of the defective MTHFR gene, one defective gene from each parent. There is a 100% chance that an individual with a homozygous genotype will pass the defective MTHFR gene to their children. People who have two defective MTHFR genes, either as 677C>T homozygotes (both copies containing the 677C>T mutation), or as compound heterozygotes (one copy with the 677C>T mutation and one copy with the 1298A>C mutation) are at an increased risk of thrombophilia. 1298A>C homozygotes do not have an increased risk of thrombophilia.
