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Genetic and Rare Diseases Information Center (GARD)

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Prothrombin thrombophilia


Other Names for this Disease
  • Factor II-related thrombophilia
  • Hyperprothrombinemia
  • Prothrombin 20210G>A thrombophilia
  • Prothrombin G20210A thrombophilia
  • Prothrombin-related thrombophilia
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Your Question

My daughter found out she is a carrier for this condition by going through genetic testing for IVF. I would like to know how I can be tested to see if I have it, but without going through all the genetic testing. Is there a single blood test I can take?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What kind of tests can determine if an individual has, or is a carrier of, prothrombin thrombophilia?

No clinical signs or symptoms are specific for prothrombin thrombophilia. A confirmed diagnosis of this condition requires specific genetic testing via DNA analysis of the F2 gene, which provides instructions for making the protein prothrombin. The test identifies the presence of a common change (mutation) called 20210G>A.[1] An individual can be a heterozygote (having one mutated copy of the F2 gene) or a homozygote (having two mutated copies).

Most heterozygotes have a mildly elevated plasma concentration of prothrombin (which can be measured in a blood test) that is approximately 30% higher than normal. However, these values can vary greatly, and the range of prothrombin concentrations in heterozygotes overlaps significantly with the normal range. Therefore, plasma concentration of prothrombin is not reliable for diagnosis of this condition.[1]

Individuals interested in learning more about testing for prothrombin thrombophilia should speak with a genetics professional or other healthcare provider.
Last updated: 4/15/2013

How is prothrombin thrombophilia inherited?

Prothrombin thrombophilia is inherited in an autosomal dominant manner. For this condition, this means that having one mutated copy of the disease-causing gene (F2) in each cell may be sufficient to cause signs or symptoms of the condition. The mutation in the F2 gene that causes prothrombin thrombophilia is called 20210G>A (also called the 20210G>A allele).[1] An individual can be heterozygous (having the mutation in only one copy of the F2 gene) or homozygous (having a mutation in both copies of the F2 gene). Heterozygosity results in an increased risk for thrombosis; homozygosity results in more severe thrombophilia and/or increased risk for thrombosis.[1]

All individuals reported to date with prothrombin thrombophilia who are heterozygous for the 20210G>A allele have had an affected parent. Because of the relatively high prevalence of this allele in the general population, occasionally one parent is homozygous or both parents are heterozygous for this allele.[1]

When an individual who is heterozygous for the 20210G>A allele has children, each child has a 50% (1 in 2) risk to inherit that allele and also be heterozygous. An individual who is homozygous will always pass one of the 20210G>A alleles to each of his/her children. If two heterozygotes have children together, each child has a 25% (1 in 4) risk to be homozygous (having 2 mutated copies), a 50% risk to be heterozygous like each parent, and a 25% risk to inherit 2 normal copies of the F2 gene.
Last updated: 4/10/2013

How can I find a genetics professional in my area?

Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.

The following online resources can help you find a genetics professional in your community:
Last updated: 10/18/2013

References