Factor V Leiden

Developed by Dr. Judith Allanson, Ms. Shawna Morrison and Dr. June Carroll Last updated Dec 2014

Disclaimer

• This presentation is for educational purposes only and should not be used as a substitute for clinical judgement. GEC-KO aims to aid the practicing clinician by providing informed opinions regarding genetic services that have been developed in a rigorous and evidence-based manner. Physicians must use their own clinical judgement in addition to published articles and the information presented herein. GEC-KO assumes no responsibility or liability resulting from the use of information contained herein.

Objectives• Following this session the learner will be able to:– Refer to their local genetics centre and/or order genetic

testing appropriately for factor V Leiden– Discuss and address patient concerns regarding family

history of factor V Leiden– Find high quality genomics educational resources

appropriate for primary care

Case

• Mary, 19yo female in good health

• Wishes to discuss birth control options

d.88

VTE at age 30

19

d.85

Hx of VTE during last two

pregnancies

4950556052

A&W A&W

A&W

Hx multiple VTEsObese

Smoker

Hx VTEObese

Smoker

What is thrombophilia?• A tendency to develop venous thromboembolism

(VTE) on the basis of a hypercoagulable state, owing to inherited and/or acquired disorders of blood coagulation or fibrinolysis– VTE is a multifactorial disorder resulting from the

interaction between an array of acquired and genetic factors

Martinelli et al 2014 Nat Rev Cardiol

What is factor V?

FIXa

FXaFX

Prothrombin(II)

Thrombin (IIa)

Thrombomodulin

Free protein S

APC

Protein C

Endothelial Protein C Receptor

Ca2

+

FVIIIa

FVa

Endothelium

• Figure shows the anticoagulant mechanisms of the protein C–protein S system

• Factor V (FV) is a clotting factor with activity regulated by the anti-coagulant activated Protein C (APC)

• FV is one of many components of the clotting cascade, which is ideally in homeostasis so as to prevent a bleeding disorder e.g. thrombophilia

What is factor V Leiden (FVL)?• The mutation (Leiden) in

the factor V (FV) gene results in FV being inactivated more slowly by APC, generating more thrombin and thus increasing the potential for thrombosis

• Some individuals may inherit more than one risk factor, i.e. FVL and prothrombin mutations are seen in 1/1000 individuals

FIXa

FXaFX

Prothrombin(II)

Thrombin (IIa)

Thrombomodulin

Free protein S

APC

Protein C

Endothelial Protein C Receptor

Ca2

+

FVIIIa

FVa

Thrombin (IIa)Thrombin

(IIa)Thrombin

(IIa)Thrombin (IIa)

Thrombin (IIa)

Endothelium

What is factor V Leiden (FVL)?• FVL is inherited in an autosomal dominant manner• About 5% of the Caucasian population carries FVL. The

prevalence is lower in Hispanic Americans and African Americans.

• Homozygosity for FVL (carrying the change in both FVL genes) occurs much less often, in about 1 per 5000 Caucasian individuals

• ~10% of FVL heterozygotes develop VTE over their lifetime• ~50% of individuals with familial thrombophilia are found to

have FVL• Heart attack, arterial thrombosis and ischemic stroke are not

associated with FVL

• Other co-existing inherited and acquired disorders and circumstantial risk factors affect clinical expression of FVL

What is factor V Leiden (FVL)?

Who should be offered genetic testing and/or referral for consultation?

A first unprovoked VTE at any age (especially age <50 years)A history of recurrent VTEVenous thrombosis at unusual sites (e.g., cerebral, mesenteric, hepatic, or portal veins)VTE and a strong family history of thrombotic diseaseVTE during pregnancy or the puerperiumVTE associated with the use of estrogen contraception or hormone replacement therapy (HRT)A first VTE and a first-degree family member with VTE < 50 years

Testing may be appropriate in other clinical circumstances (see GEC-KO point of care tool for more)

Who should not be offered genetic testing?• FVL testing is not routinely recommended: For the general population During routine pregnancy screening Before prescribing estrogen contraception, HRT or selective

estrogen receptor modulators (SERMs) For prenatal testing or screening of asymptomatic newborns,

neonates, and children For patients with a personal or family history of arterial

thrombosis (acute coronary syndrome or stroke), unless unexplained in an individual under age 50

What does a positive test result mean?• Population studies suggest that about 10% of FVL carriers

develop VTE over their lifetime• The risk is higher for those with a family history of

thrombophilia (~25-40%)• The absolute risk for VTE is small– For example, in the general population women under age

40 have a background risk of VTE of 8/100,000, whereas female FVL carriers of the same age have a VTE risk of 24/100,000 and the homozygote risk for women in that age range is 8/10,000

• FVL carriers do not have an increased mortality

How will genetic testing help you and your patient?

• Asymptomatic FVL carriers:– Can be educated about VTE high-risk circumstances, signs

and symptoms of VTE, and the potential need for prophylactic treatment in high risk circumstances

– Additional conditions can be screened for• FVL is often seen with other inherited and/or acquired disorders.

Knowledge of these can help better assess the absolute risk of thrombosis. (see GEC-KO point of care tool for more)

– During high-risk circumstances prophylactic anticoagulation may prevent some VTE episodes• However, there is no evidence confirming the benefit of primary

prophylaxis for asymptomatic FVL heterozygotes• Consultation with a specialist may be considered

Are there harms or limitations of genetic testing?

• Does not detect all possible thrombophilia conditions

• Clinical utility is limited• Absolute VTE risk is low• Surveillance and management guidelines are

limited and inconsistent

Cased.88

VTE at age 30

19

d.85

Hx of VTE during last two

pregnancies

4950556052

A&W A&W

A&W

Hx multiple VTEsObese

Smoker

Hx VTEObese

Smoker

• Family history strongly suggestive of autosomal dominant FVL

• Encourage patient’s mother to be tested

• If patient’s mother won’t be tested, offer genetic testing to your patient

• May affect contraceptive use decision-making

Pearls•Factor V Leiden (FVL) is the most common genetic risk factor for venous thromboembolism (VTE) •It occurs in about 5% of the Caucasian population•It is considered to be a moderate risk factor for VTE•Clinical expression is influenced by co-existing genetic factors, acquired and circumstantial risk factors• It seems to have little or no effect on recurrence risk of VTE, does not influence treatment following a VTE event, and FVL is not an indication for primary prophylactic treatment in asymptomatic carriers

Pearls (continued)

• There is consensus that, in some circumstances, genetic testing for FVL has utility, as carriers should be educated about circumstances that might increase the likelihood of VTE, the signs and symptoms of VTE, and the potential need for prophylactic anticoagulation in high-risk circumstances

References[1] Kujovich JL. Factor V Leiden thrombophilia. Genet Med 2011; 13(1): 1-13[2] Martinelli I, De Stefano V, Mannucci PM. Inherited risk factors for venous thromboembolism. Nat Rev

Cardiol 2014; 11(3):140-56[3] Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group.

Recommendations from the EGAPP Working Group: routine testing for Factor V Leiden (R506Q) and prothrombin (20210G>A) mutations in adults with a history of idiopathic venous thromboembolism and their adult family members. Genet Med 2011;13(1):67-76

[4] Grody WW, Griffin JH, Taylor AK, Korf BR, Heit JA, ACMG Factor V. Leiden Working Group. American College of Medical Genetics consensus statement on factor V Leiden mutation testing. Genet Med 2001; 3(2):139-48

[5] Geerts WH, Bergqvist D, Pineo GF, Heit JA, Samama CM, Lassen MR, Colwell CW; American College of Chest Physicians. Prevention of venous thromboembolism: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; 133(6 Suppl):381S-453S.

[6] Chan WS, Rey E, Kent NE; VTE in Pregnancy Guideline Working Group, Chan WS, Kent NE, Rey E, Corbett T, David M, Douglas MJ, Gibson PS, Magee L, Rodger M, Smith RE. Venous thromboembolism and antithrombotic therapy in pregnancy. J Obstet Gynaecol Can 2014; 36(6):527-53

[7] Kearon C, Kahn SR, Agnelli G, Goldhaber S, Raskob GE, Comerota AJ, American College of Chest Physicians. Antithrombotic therapy for venous thromboembolic disease: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008;133:454S–545S