INHERITED THROMBOPHILIA

INHERITED THROMBOPHILIA

Defects in physiologic anticoagulant pathways

Increased production of procoagulant

• Antithrombin deficiency• Protein C deficiency• Protein S deficiency• Factor V Leiden (APC resistance)

• Prothrombin G20210A gene mutation

Many other genes affect coagulation – the contribution of mutations in these genes to thrombotic risk is important but presently difficult to quantify

THE ANTITHROMBIN SYSTEM

Antithrombin inhibits thrombin, Xa, IXa, XIa

E CTM

THE PROTEIN C SYSTEMA negative feedback loop that degrades factors Va, VIIIa

IIa

IIa

P S

APC

VaVi

VIIIa

VIIIi

P C

• Typically 30-60% of normal plasma activity of affected protein

• Genetically heterogeneous Type 1: low antigen and activity Type 2: normal antigen, low activity (missense

mutations)• Thrombotic risk varies from family to family• Together account for approximately 10-15% of

cases of inherited thrombophilia

THROMBOPHILIA DUE TO DEFICIENCY OF ANTICOAGULANT PROTEIN

Antithrombin, Protein C, Protein S

• Missense mutation changes amino acid 506 of factor V from arginine to glycine

• Mutation is at preferred protein C cleavage site, slows inactivation of factor Va by protein C

• Factor Va procoagulant activity not affected Not a “deficiency”

• Single mutation responsible for all cases Usually diagnosed by DNA testing

• Very common About 5% of US population heterozygous, 0.05%

homozygous

FACTOR V LEIDENA highly prevalent inherited risk factor for thrombosis

FACTOR V LEIDENPrevalence in different ethnic groups

Lancet 1995;346:1133

GroupAllele

frequencyHeterozygote

frequencyHomozygote

frequency

European 4.4% 8.6% 0.2%

Asia Minor 0.6 1.2 0.004

African 0 0 0

SE Asian 0 0 0

Native American

0 0 0

• Mutation in 3' untranslated (non-coding) part of prothrombin gene

• No effect on prothrombin structure or function

• Heterozygotes have 5-10% higher plasma levels of prothrombin

• Heterozygotes have 2-3 fold risk of venous thromboembolism

• About 1-2% of population heterozygous; 5-7% of young patients with DVT/PE

• Diagnosis: DNA testing

PROTHROMBIN G20210A GENE MUTATION

GENETIC RISK FACTORS FOR THROMBOSIS

PhenotypeApproximate prevalence in thrombophilia

Number of genotypes

Antithrombin deficiency 5% or less Many

Protein C deficiency about 5% Many

Protein S deficiency 5% or less Many

Factor V Leiden 40-50% One

Prothrombin G20210A 5-7% One

CLINICAL FEATURES OF INHERITED THROMBOPHILIA

INHERITED THROMBOPHILIAClinical findings in homozygous state

CONDITIONCLINICAL FINDINGS IN HOMOZYGOTES

Antithrombin III deficiency lethal?

Protein C deficiency neonatal purpural fulminans

Protein S deficiency neonatal purpural fulminans (? - rare)

FVL Prothrombin mutation

Premature thrombosis in many (most?) - some asymptomatic

HOMOZYGOUS PROTEIN C DEFICIENCY WITH NEONATAL PURPURA FULMINANS

• Venous thromboembolism No convincing evidence of increased risk of

arterial thrombosis

• Onset often in 20s and 30s Many carriers are asymptomatic throughout

life

• About half of VTE episodes associated with other risk factors, half "idiopathic"

• Increased risk of pregnancy loss

INHERITED THROMBOPHILIAClinical Features in Heterozygotes

RISK OF VTE HIGHER WITH INHERITED ANTICOAGULANT PROTEIN DEFICIENCY THAN FVL, PROTHROMBIN MUTATION

No defect

AT

PC

PS

PT

FVL

Blood 2009;113:5314

Thrombosis-free survival in relatives of patients with thrombophilia

INCREASED THROMBIN GENERATION IN HETEROZYGOUS FACTOR V LEIDEN

Can such testing help predict risk of thrombosis?

CONTROLS FVL CONTROLS FVL

• Genetic heterogeneity – mutation detection more difficult than for FVL, PT mutations

• Blood levels affected by other conditions, drugs Heparin lowers antithrombin levels Warfarin lowers protein C, protein S levels Liver disease lowers all three Pregnancy, inflammation, contraceptives decrease free

protein S• Some mutations affect protein activity, not antigen

Measurements of anticoagulant protein levels in unselected patients have low predictive value

INHERITED THROMBOPHILIADiagnosing anticoagulant protein deficiency

• Likelihood that a gene mutation is present if measured protein activity is 50% of normal:– Antithrombin = 75%– Protein C =60%– Protein S = 25%

Thromb Haemost 2012; 108: 247

Low blood level ≠ inherited deficiency

LOW PROTEIN S LEVEL IS A POOR PREDICTOR OF THROMBOSIS RISK IN THE GENERAL POPULATION

The Leiden Thrombophilia Study

Koster et al, Blood 1995;85:2756

Relative risk of thrombosis

95% CI

Low total protein S (one measurement)

0.7 0.3-1.8

Low total protein S (two measurements)

0.8 0.2-3.0

Low free protein S 1.6 0.6-4.0

Low free and total protein S

1.7 1.0-4.7

• Subjects: 122-member protein S-deficient family, 44 of whom carried Gly295-Val mutation

• Diagnosis of protein S deficiency established by DNA testing

Hazard ratio for thrombosis associated with carriage of protein S mutation was 11.5 (95% CI = 4.33-30.6)

PROTEIN S DEFICIENCY IS A STRONG PREDICTOR OF THROMBOTIC RISK IN A

FAMILY WITH A KNOWN MUTATION

Simmonds et al, Ann Intern Med 1998;128:8

Family history predicts thrombotic risk just as well as laboratory testing for thrombophilia

A case-control study

Arch Intern Med 2009;169:610

Event OR for event with positive FH

OR for event with positive test for thrombophilia

Unprovoked VTE 2.5 2.3

Provoked VTE 16.4 21.2

Fam Hx VTE Odds ratio for thrombosis (95% CI)

Negative 1 (reference)

Any relative 2.2 (1.9-2.6)

Relative < 50 2.7 (2.2-3.4)

> 1 Relative 3.9 (2.7-5.7)

The presence of thrombophilia does not predict thrombotic risk in the absence of a family hx of VTE

Thromb Haemost 2011;106:646

Event in proband leading to diagnosis of thrombophilia

Incidence of VTE in relatives per 1000 patient-yrs (95% CI)

Carriers Non-carriers

VTE 1.6 (1.2-2.2) 0.5 (0.3-1.0)

Arterial thrombosis 0.5 (0.1-2.8) 0.8 (0.2-3.0)

Obstetric complication 0.6 (0.2-1.6) 0.0 (0-0.8)

Asymptomatic 0.3 (0.1-1.2) 0.0 (0-0.7)

RISK OF THROMBOSIS IN THROMBOPHILIA

EFFECT OF GENE DOSERelative risk of thrombosis in heterozygous

and homozygous factor V Leiden

Rosendaal et al, Blood 1995;85:1504

Genotype Relative Risk

Normal 1

Heterozygous 7

Homozygous 80

EFFECT OF GENE INTERACTIONSCo-inheritance of protein C deficiency and

factor V Leiden within a family

Koeleman et al, Blood 1994;84:1031

Gene Mutation

Protein C and Factor V

Thrombosis present (%)

16 (73)

Thrombosis absent (%)

6 (27)

Protein C 5 (31) 11 (69)

Factor V 2 (13) 11 (87)

None 0 11 (100)

INTERACTION WITH ACQUIRED RISK FACTORSOral contraceptive

Vandenbroucke et al, Lancet 1994;344:1453

RISK FACTORRELATIVE RISK OF

THROMBOSIS

Oral contraceptive 4

Factor V Leiden 8

Both 35

INTERACTION WITH ACQUIRED RISK FACTORSEstrogen replacement

Rosendaal, 2001

RISK FACTORRELATIVE RISK OF

THROMBOSIS

Estrogen replacement 3.5

Factor V Leiden 4.6

Both 11

FACTOR V LEIDEN INCREASES RISK OF VENOUS, BUT NOT ARTERIAL, THROMBOSIS

Physicians' Health Study (15,000 subjects)

Ridker et al, NEJM 1995;332:912

Type of thrombosis0

2

4

6

8

10

12

% H

eter

ozy

go

tes

None MI StrokeMIor

Stroke

DVTorPE

P = 0.9

P = 0.4

P = 0.7

P = 0.02

WHAT ARE THE IMPLICATIONS OF A POSITIVE TEST FOR

THROMBOPHILIA IN AN ASYMPTOMATIC PERSON?

RELATIVE RISK OF VENOUS EVENTS IN RELATIVES OF PATIENTS WITH THROMBOPHILIA

Vossen et al, J Thromb Haemost 2004;2:1526

THE ABSOLUTE RISK OF VENOUS EVENTS IN ASYMPTOMATIC RELATIVES OF THROMBOPHILIC PATIENTS IS LOW

Vossen et al, J Thrombos Haemost 2005;3:459

Bleeding risk with long term anticoagulation estimated at 1-3%/year

INCIDENCE OF FIRST VTE EVENTS IN SPECIFIC RISK SITUATIONS IN THROMBOPHILIC INDIVIDUALS

Vossen et al, J Thrombos Haemost 2005;3:459

Analysis restricted to individuals not given prophylaxis

RISK SITUATION THROMBOPHILICINDIVIDUALS CONTROLS

Travel > 8h 0% (0/504) 0% (0/1244)

Surgery or immobilization > 2 w

2% (3/176) 0.04% (2/407)

Plaster cast 0% (0/33) 0% (0/71)

Cancer 10% (1/10) 6% (1/17)

Pregnancy 7% (2/28) 0% (0/75)

SHOULD ORAL CONTRACEPTIVES ROUTINELY BE WITHHELD FROM WOMEN WITH FACTOR V LEIDEN?PREDICTED OUTCOMES WITH ALTERNATIVE CONTRACEPTIVE METHODS

Oral contraceptive

Levonorgesterol-IUD

Copper IUD Condom

1st VTE/100 pregancy-yr

0.55 0.25 0.25 0.25

VTE/100,000 pregnancy-yr

550 250 250 250

Unintended pregnancies/ 100,000 p-y

200 700 1400 12,000

Additional cases of VTE

6 20 40 336

Total # VTE 556 270 290 586

Blood 2011;118:2055

MANAGEMENT OF ASYMPTOMATIC INDIVIDUALS WITH INHERITED

THROMBOPHILIA

• Counseling/reassurance• Prophylaxis in high-risk situations• Carefully consider risk/benefit ratio and

alternatives when prescribing oral contraceptives or HRT

IS THE MANAGEMENT OF PATIENTS WITH VTE AFFECTED BY

THE RESULTS OF THROMBOPHILIA TESTING?

The presence of inherited thrombophilia does not usually affect treatment of patients with VTE

• Idiopathic VTE is a strong independent predictor of recurrence risk, and so is a potential indication for long-term anticoagulation

• The presence of inherited thrombophilia is not a good predictor of VTE recurrence risk and so should not be used as the basis for prolonging therapy

The risk of recurrent venous thromboembolism is higher in patients with idiopathic events

Lancet 2003; 362: 523–26

Idiopathic VTE

Postop VTE

Other risk factor

The risk of recurrent VTE is not significantly affected by the presence of inherited thrombophilia

Lancet 2003; 362: 523–26

Hazard ratio 1.50

(95% CI = 0.82-2.77)

p=0.187

A diagnosis of thrombophilia does not affect overall survival after an episode of VTE

Thromb Haemost 2013;1:79

Median followup time = 5 yrs

Warfarin-induced skin necrosis in a protein C-deficient patient

Compound heterozygote for FVL and protein C deficiencyDay 5 of warfarin treatment, on heparinConcomitant bilateral adrenal hemorrhagic infarction

WARFARIN LOWERS LEVELS OF PROTEIN C FASTER THAN LEVELS OF PROCOAGULANT VITAMIN K-DEPENDENT PROTEINS

Protein C

Prothrombin

Transient hypercoagulability?

THROMBOPHILIA AND PREGNANCY

INCREASED RISK OF FETAL LOSS IN WOMEN WITH HERITABLE THROMBOPHILIA

European Prospective Cohort on Thrombophilia (1384 women)

Lancet 1996;348:913

CONDITIONRR OF

STILLBIRTH95% CI

RR OF MISCARRIAGE

95% CI

ANTITHROMBIN DEFICIENCY

5.2 1.5-18.1 1.7 1.0-2.8

PROTEIN C DEFICIENCY

2.3 0.6-8.3 1.4 0.9-2.2

PROTEIN S DEFICIENCY

3.3 1.0-11.3 1.2 0.7-1.9

FACTOR V LEIDEN 2 0.5-7.7 0.9 0.5-1.5

COMBINED DEFECTS 14.3 2.4-86.0 0.8 0.2-3.6

ALL THROMBOPHILIA 3.6 1.4-9.4 1.27 0.94-1.71

LATE FETAL LOSS IN THROMBOPHILIADue to factor V or prothrombin mutation

NEJM 2000;343;1015

Mutation% of women with late fetal

loss

% of women with normal pregnancy

RR (95% CI)

Factor V or prothrombin

16 6 3.3 (1.4-7.8)

Factor V Leiden

7 3 3.2 (1.0-10.9)

Prothrombin 9 3 3.3 (1.1-10.3)

BUT…

There is no evidence that anticoagulant (LMWH) or

antiplatelet (ASA) prophylaxis improves pregnancy outcomes

in women with inherited thrombophilia

ANTICOAGULATION IN WOMEN WITH RECURRENT PREGNANCY LOSS

2012 ACCP CONSENSUS RECOMMENDATIONS

• For women with recurrent pregnancy loss and no evidence of antiphospholipid syndrome, whether or not they have inherited thrombophilia:No antithrombotic therapy recommended

CHEST 2012; 141:e691S

VTE PROPHYLAXIS DURING PREGNANCY2012 ACCP CONSENSUS RECOMMENDATIONS

• Women homozygous for FVL or prothrombin mutation, no prior VTE –If positive FH: antepartum prophylaxis (LWMH)

and postpartum prophylaxis x 6 weeks (warfarin or LMWH)

–If no FH: antepartum “clinical vigilance” and postpartum prophylaxis x 6 weeks

CHEST 2012; 141:e691S

VTE PROPHYLAXIS DURING PREGNANCY2012 ACCP CONSENSUS RECOMMENDATIONS

• All other forms of thrombophilia, no prior VTE –If positive FH: antepartum “clinical vigilance”

and postpartum prophylaxis x 6 weeks (LMWH, warfarin OK if not protein C or S deficient)

–If no positive FH: clinical vigilance only

CHEST 2012; 141:e691S

WHO TO TEST?

Inherited thrombophilia is more likely if a patient with VTE

Is young Has a family history of VTE Had unprovoked VTE Had warfarin-induced skin necrosis (protein C)

Test results rarely affect patient management!

WHEN TO TEST?• FVL, prothrombin mutation: any time (not informative after liver

transplantation)• Antithrombin:

Not during acute thrombosis Not during pregnancy or estrogen/OCP use Off heparin/LMWH at least 2 weeks

• Protein C: Off warfarin (preferable), or on stable warfarin dose at least 2

weeks Preferably not during acute thrombosis

• Protein S: As for protein C Not during pregnancy, OCP use or acute inflammation

Neonatal period, DIC, liver disease, asparaginase Rx can all cause acquired deficiency of AT, PC, PS

Testing should usually be done in the outpatient setting

ACQUIRED THROMBOPHILIA

• Antiphospholipid syndrome• Hyperhomocysteinemia (may be inherited)• Cancer• Myeloproliferative disorders• Nephrotic syndrome• Pregnancy• Oral contraceptive/estrogen• Hyperviscosity

HOMOCYSTEINE

SEVERE• homozygous cystathione beta-synthase deficiency

(1:250,000)• homozygous methylenetetrahydrofolate reductase

deficiency MILD OR MODERATE

• heterozygous CBS deficiency (0.3-1.4% of population)• thermolabile variant of MTHFR (5% of population)• B12, folate or B6 deficiency• Aging• Chronic renal failure

CAUSES OF HYPERHOMOCYSTEINEMIA

HIGHER HOMOCYSTEINE LEVELS ARE ASSOCIATED WITH VASCULAR RISK

Meta-analysis

Condition Increase in risk per 5 micromole increase in plasma HC (95% CI)

Ischemic heart disease 1.32 (1.19-1.45)

Stroke 1.59 (1.29-1.96)

VTE 1.60 (1.15-2.22)

BMJ 2002;325:1202

BUT…

LOWERING HOMOCYSTEINE DOES NOT DECREASE VASCULAR RISK

• VISP trial (JAMA 2004): Moderate reduction in HC had no effect on vascular risk during 2 yr followup

• HOPE 2 trial (NEJM 2006): Vitamin supplements lowered HC levels but had no effect on vascular risk

• NORVIT trial (NEJM 2006): More aggressive vitamin supplementation associated with increased vascular risk

• VITRO study (Blood 2007): Lowering HC did not prevent recurrent VTE

ANTIPHOSPHOLIPID ANTIBODIES

ANTIPHOSPHOLIPID ANTIBODIES

• Lupus anticoagulant• Cardiolipin antibodies (IgG, IgM)• Beta-2 glycoprotein I antibodies (IgG, IgM)

• Thrombotic risk associated with higher antibody levels, positive tests for more than one type of antibody

INCIDENCE OF ANTIPHOSPHOLIPID ANTIBODIES

Love and Santoro, Ann Intern Med 1990

PATIENT GROUP ANTIBODY TYPEAPPROX

INCIDENCE

SLE LAC 30%

SLE aCL 40%

Blood donors aCL 2%

Healthy elderly aCL 52%

• Thrombosis (arterial and venous)• Recurrent fetal loss• Hematologic abnormalities:

Immune thrombocytopenia Immune hemolytic anemia

CLINICAL CONDITIONS ASSOCIATED WITH ANTIPHOSPHOLIPID ANTIBODIES

The “antiphospholipid syndrome”

Arthritis & Rheumatism 2002;46:1019-27

• 1% or less of APL patients• Generalized vasculopathy (?thrombotic or

inflammatory)• Livedo reticularis• Multiple organ system involvement

Renal failure Hypertension ARDS CNS

• Rapid progression; sudden death in some patients• Treatment: anticoagulation, plasma exchange, ?

immunosuppresion

CATASTROPHIC ANTIPHOSPHOLIPID SYNDROME(Asherson, 1992)

In study of 22000 male physicians:

aCL titer above 95th percentile associated with • 5-fold increase in relative risk of DVT• No significant increase in ischemic stroke risk

ANTIPHOSPHOLIPID ANTIBODIES AND THROMBOSIS IN HEALTHY PEOPLE

Physicians Health Study

Ginsberg et al, Ann Intern Med 1992

IgG Anticardiolipin Antibodies and Risk of Recurrence or Death in Patients with VTE After Stopping Anticoagulation

Recurrence Death

Am J Med 1998; 104:332

Incidence of first thromboembolic events in asymptomatic “high-risk” individuals with antiphospholipid antibodies

Blood 2011; 118:4714

“High risk” defined as having persistently positive tests for lupus anticoagulant, cardiolipin antibodies and ß2-glycoprotein I antibodies

Blood 2013;122:817-824

“Although a positive APLA test appears to predict an increased risk of recurrence in patients with a first VTE, the strength of this association is uncertain because the available evidence is of very low quality”

ANTIPHOSPHOLIPID SYNDROMECLINICAL CRITERIA

1. One or more documented episodes of arterial, venous, or small vessel thrombosis (other than superficial venous thrombosis) in any tissue or organ – Thrombosis must be confirmed by objective validated criteria– For histopathologic confirmation, thrombosis should be present without significant evidence of

inflammation in the vessel wall

2. Pregnancy morbiditya. One or more unexplained deaths of a morphologically normal fetus at or beyond the 10th week

of gestation, with normal fetal morphology documented by ultrasound or by direct examination of the fetus, or

b. One or more premature births of a morphologically normal neonate before the 34th week of gestation because of: (i) eclampsia or severe pre-eclampsia defined according to standard definitions, or (ii) recognized features of placental insufficiency, or

c. Three or more unexplained consecutive spontaneous abortions before the 10th week of gestation, with maternal anatomic or hormonal abnormalities and paternal and maternal chromosomal causes excluded

J Thromb Haemost 2006;4:295

ANTIPHOSPHOLIPID SYNDROMELABORATORY CRITERIA

1. Lupus anticoagulant (LAC) present in plasma, on two or more occasions at least 12 weeks apart, detected according to the guidelines of the International Society on Thrombosis and Haemostasis (Scientific Subcommittee on LACs/phospholipid- dependent antibodies)

2. Anticardiolipin antibody (aCL) of IgG and/or IgM isotype in serum or plasma, present in medium or high titer (i.e., > 40 GPL or MPL, or > the 99th percentile), on two or more occasions at least 12 weeks apart, measured by a standardized ELISA

3. Anti-ß2 glycoprotein-I antibody of IgG and/or IgM isotype in serum or plasma (in titer >the 99th percentile), present on two or more occasions at least 12 weeks apart, measured by a standardized ELISA, according to recommended procedures

APL syndrome considered present if at least one of the clinical and one of the laboratory criteria are present

J Thromb Haemost 2006;4:295

TREATMENT OF PATIENTS WITHANTIPHOSPHOLIPID ANTIBODIES

Asymptomatic: no treatment History of thrombosis:

– Consider prolonged treatment in selected patients • Recurrent or unprovoked thrombosis (arterial or

venous)• Persistently high antibody levels• More than 1 APL antibody test positive

– Most patients can be treated with standard anticoagulant regimen• Two RCTs have shown inferior outcomes with high

intensity warfarin treatment• A few patients exhibit warfarin failure – consider long

term LMWH treatment (no data yet on newer oral anticoagulants)

ANTIPHOSPHOLIPID ANTIBODIES AND FETAL LOSS

• Antiphospholipid antibodies associated with lower live birth rates in unselected “low-risk” pregnancies

• Live birth rates in untreated women with APL and at least one fetal loss have ranged from 10-85% in published studies

• Aspirin and heparin have been associated with higher live-birth rates in several studies, but most of these did not include a placebo-treated arm

Arth Rheum 2004;50:1028

ANTIPHOSPHOLIPID ANTIBODIES AND FETAL LOSS

• Testing for APL should be restricted to women with at least three consecutive miscarriages

• Other causes of pregnancy loss (especially abnormal karyotypes) should be ruled out

• If criteria for obstetric APL syndrome met, treat with aspirin and/or LMWH during pregnancy and postpartum period

Arth Rheum 2004;50:1028

ANTICOAGULATION IN WOMEN WITH APLA AND RECURRENT PREGNANCY LOSS

2012 ACCP CONSENSUS RECOMMENDATIONS

• Women who meet lab and clinical criteria for obstetric APLA:

Antepartum prophylactic or intermediate-dose LMWH plus low dose ASA

CHEST 2012; 141:e691S