1. INHERITED THROMBOPHILIA

2. INHERITED THROMBOPHILIA
Defects in physiologic anticoagulant pathways
Antithrombin deficiency
Protein C deficiency
Protein S deficiency
Factor V Leiden
Increased production of procoagulant
Prothrombin G20210A gene mutation
Many other genes affect coagulation – the contribution of mutations in these genes to thrombotic risk is presently impossible to quantify

3. INHERITED CONDITIONS NOT ASSOCIATED WITH CLINICALLY SIGNIFICANT RISK OF THROMBOSIS
MTHFR mutations
Plasminogen deficiency and other defects in fibrinolysis

4. THROMBOPHILIA DUE TO DEFICIENCY OF ANTICOAGULANT PROTEIN
Antithrombin, Protein C, Protein S
Typically 30-60% of normal plasma activity of affected protein
Dominant inheritance
Genetically heterogeneous
Type 1: low antigen and activity
Type 2: normal antigen, low activity (missense mutations)
Type 3 (Protein S): Increased binding to C4b binding protein, decreased free protein S level/activity
Thrombotic risk varies from family to family
Together account for approximately 10-15% of cases of inherited thrombophilia

5. Plasma levels of anticoagulant proteins are poor predictors of inherited 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

6. FACTOR V LEIDEN A highly prevalent inherited risk factor for thrombosis
Polymorphism eliminates a preferred protein C cleavage site, slows inactivation of factor Va by protein C
Factor Va procoagulant activity not affected
Not a “deficiency”
Same genotype responsible for all cases
Diagnosed by DNA testing
Very common
About 5% of US population heterozygous, 0.05% homozygous
High allele frequency implies evolutionary advantage

7. Prevalence in different ethnic groups Heterozygote frequency
FACTOR V LEIDEN
Prevalence in different ethnic groups
Allele frequency
Heterozygote frequency
Homozygote frequency
Group
European
4.4%
8.6%
0.2%
Asia Minor
0.6
1.2
0.004
African
SE Asian
Native American
Lancet 1995;346:1133

8. 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 thrombosis 2 4 6 8 10 12
% Heterozygotes
None MI
Stroke or
DVT PE
P = 0.9
P = 0.4
P = 0.7
P = 0.02

9. PROTHROMBIN G20210A GENE POLYMORPHISM
Polymorphism 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, 2-3 fold relative risk of venous thromboembolism
About 1-2% of population heterozygous
Diagnosis: DNA testing

10. CLINICAL FEATURES OF INHERITED THROMBOPHILIA

11. INHERITED THROMBOPHILIA
Clinical findings in homozygous state
CLINICAL FINDINGS IN HOMOZYGOTES
CONDITION
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

12. HOMOZYGOUS PROTEIN C DEFICIENCY WITH NEONATAL PURPURA FULMINANS

13. INHERITED THROMBOPHILIA
Clinical Features in Heterozygotes
Venous thromboembolism
No convincing evidence of increased risk of arterial thrombosis
Onset often in 20s and 30s
Many carriers asymptomatic throughout life
About half of VTE episodes unprovoked
Increased risk of pregnancy loss

14. Thrombotic risk varies with type of thrombophilia
Proportion of individuals from thrombphilic families who have an episode of VTE by age 50:
Protein C, protein S or antithrombin deficiency: 40-50%
Factor V Leiden or prothrombin polymorphism: 10-15%
Blood 2009;113:5314

15. Relative risk of VTE in individuals with low plasma protein S vs protein S mutation
Koster et al, Blood 1995;85:2756
Relative risk of thrombosis
95% CI
Low plasma protein S (general population)
0.7
Protein S mutation in thrombophilic family
11.5
Simmonds et al, Ann Intern Med 1998;128:8

16. Family history predicts thrombotic risk just as well as laboratory testing for thrombophilia A case-control study
Fam Hx VTE
Odds ratio for thrombosis (95% CI)
Negative
1 (reference)
Any relative
2.2 ( )
Relative < 50
2.7 ( )
> 1 Relative
3.9 ( )
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
Arch Intern Med 2009;169:610

17. The presence of thrombophilia does not predict thrombotic risk in the absence of a family hx of VTE
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 ( ) ( )
Arterial thrombosis
0.5 ( ) ( )
Obstetric complication
0.6 ( ) (0-0.8)
Asymptomatic
0.3 ( ) (0-0.7)
Thromb Haemost 2011;106:646

18. RISK OF THROMBOSIS IN THROMBOPHILIA

19. EFFECT OF GENE DOSE
Relative risk of thrombosis in heterozygous and homozygous factor V Leiden
Genotype
Relative Risk
Normal 1
Heterozygous 7
Homozygous 80
Rosendaal et al, Blood 1995;85:1504

20. EFFECT OF GENE INTERACTIONS
Co-inheritance of protein C deficiency and factor V Leiden within a family
Thrombosis present (%)
Thrombosis absent (%)
Gene Mutation
Protein C and Factor V
16 (73)
6 (27)
Protein C
5 (31)
11 (69)
Factor V
2 (13)
11 (87)
None
11 (100)
Koeleman et al, Blood 1994;84:1031

21. INTERACTION WITH ACQUIRED RISK FACTORS
Oral contraceptive
RELATIVE RISK OF THROMBOSIS
RISK FACTOR
Oral contraceptive 4
Factor V Leiden 8
Both 35
Vandenbroucke et al, Lancet 1994;344:1453

22. INTERACTION WITH ACQUIRED RISK FACTORS
Estrogen replacement
RELATIVE RISK OF THROMBOSIS
RISK FACTOR
Estrogen replacement
3.5
Factor V Leiden
4.6
Both 11
Rosendaal, 2001

23. WHAT ARE THE IMPLICATIONS OF A POSITIVE TEST FOR THROMBOPHILIA IN AN ASYMPTOMATIC PERSON?

24. RELATIVE RISK OF VENOUS EVENTS IN RELATIVES OF PATIENTS WITH THROMBOPHILIA
Vossen et al, J Thromb Haemost 2004;2:1526

25. 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

26. INCIDENCE OF FIRST VTE EVENTS IN SPECIFIC RISK SITUATIONS IN THROMBOPHILIC INDIVIDUALS
Vossen et al, J Thrombos Haemost 2005;3:459
RISK SITUATION
THROMBOPHILIC
INDIVIDUALS
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)
Analysis restricted to individuals not given prophylaxis

27. 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
VTE/100,000 pregnancy-yr
550
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

28. 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

29. IS THE MANAGEMENT OF PATIENTS WITH VTE AFFECTED BY THE RESULTS OF THROMBOPHILIA TESTING?

30. 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

31. 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 = )
p=0.187

32. 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

33. Warfarin-induced skin necrosis in a protein C-deficient patient
Compound heterozygote for FVL and protein C deficiency
Day 5 of warfarin treatment, on heparin
Concomitant bilateral adrenal hemorrhagic infarction

34. WARFARIN LOWERS LEVELS OF PROTEIN C FASTER THAN LEVELS OF PROCOAGULANT VITAMIN K-DEPENDENT PROTEINS
Prothrombin
Transient hypercoagulability?

35. THROMBOPHILIA AND PREGNANCY

36. INCREASED RISK OF FETAL LOSS IN WOMEN WITH HERITABLE THROMBOPHILIA
European Prospective Cohort on Thrombophilia (1384 women)
Lancet 1996;348:913
RR OF STILLBIRTH
RR OF MISCARRIAGE
CONDITION
95% CI
95% CI
ANTITHROMBIN DEFICIENCY
5.2
1.7
PROTEIN C DEFICIENCY
2.3
1.4
PROTEIN S DEFICIENCY
3.3
1.2
FACTOR V LEIDEN 2
0.9
COMBINED DEFECTS
14.3
0.8
ALL THROMBOPHILIA
3.6
1.27

37. BUT…

38. There is no evidence that anticoagulant (LMWH) or antiplatelet (ASA) prophylaxis improves pregnancy outcomes in women with inherited thrombophilia

40. 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!

41. WHEN TO TEST?
FVL, prothrombin polymorphism: any time (DNA test 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

42. ACQUIRED THROMBOPHILIA
Antiphospholipid syndrome
Hyperhomocysteinemia (may be inherited)
Inflammatory bowel disease
Cancer
Nephrotic syndrome
Myeloproliferative disorders
Pregnancy
Oral contraceptive/estrogen
Hyperviscosity

43. HOMOCYSTEINE

44. CAUSES OF HYPERHOMOCYSTEINEMIA
SEVERE
homozygous cystathione beta-synthase deficiency (1:250,000)
homozygous methylenetetrahydrofolate reductase deficiency
MILD OR MODERATE
heterozygous CBS deficiency ( % of population)
C677T polymorphism in MTHFR (10% of population homogyzous)
B12, folate or B6 deficiency
Aging
Chronic renal failure

45. 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 ( )
Stroke
1.59 ( )
VTE
1.60 ( )
BMJ 2002;325:1202

46. BUT…

47. 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

48. ANTIPHOSPHOLIPID ANTIBODIES

49. 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

50. INCIDENCE OF ANTIPHOSPHOLIPID ANTIBODIES
APPROX INCIDENCE
PATIENT GROUP
ANTIBODY TYPE
SLE
LAC
30%
SLE
aCL
40%
Blood donors
aCL 2%
Healthy elderly
aCL
52%
Love and Santoro, Ann Intern Med 1990

51. CLINICAL CONDITIONS ASSOCIATED WITH ANTIPHOSPHOLIPID ANTIBODIES The “antiphospholipid syndrome”
Thrombosis (arterial and venous)
Recurrent fetal loss
Hematologic abnormalities:
Immune thrombocytopenia
Immune hemolytic anemia

52. Arthritis & Rheumatism 2002;46:1019-27

53. CATASTROPHIC ANTIPHOSPHOLIPID SYNDROME
(Asherson, 1992)
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 (sirolimus?)

54. “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”
Blood 2013;122:

55. ANTIPHOSPHOLIPID SYNDROME CLINICAL CRITERIA
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
Pregnancy morbidity
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
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
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

56. ANTIPHOSPHOLIPID SYNDROME LABORATORY CRITERIA
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)
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
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

57. TREATMENT OF PATIENTS WITH ANTIPHOSPHOLIPID 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)

58. 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

59. 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

60. 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