Thrombophilias: Guide to Hereditary and Acquired Conditions

Thrombophilias may be hereditary or acquired and the risk/severity of thrombosis varies widely between conditions.

Hereditary Thrombophilia	Relative Risk For A First Venous Thromboembolism (Compared To Community Controls)
Factor V Leiden Heterozygous Homozygous	3x – 7x 80x
Prothrombin G20210A Heterozygous Homozygous	2x – 3x 5x
Double heterozygosity (Factor V Leiden and prothrombin G20210A)	6x
Antithrombin deficiency	5x
Protein C deficiency	4x – 6.5x
Protein S deficiency	1x – 3x
Pseudohomozygous Factor V Leiden	80x
Factor IX Padua	10x
Antithrombin resistance	2x – 3x
Factor VIII ≥150 IU/dl	3x – 5x
Factor IX ≥129 IU/dl	2.3x
Factor XI ≥121 IU/dl	2x

Adapted from: Campello E, Spiezia L, Adamo A, Simioni P. Thrombophilia, risk factors and prevention. Expert Rev Hematol. 2019 Mar 4;12(3):147–58.

Acquired Thrombophilia	Relative Risk For A First Venous Thromboembolism (Compared To Community Controls)
Antiphospholipid antibody syndrome	3x – 10x
Hyperhomocysteinemia	1.5x – 3x
Surgery	1.7x – 2.8x
Trauma	3x – 5x
Pregnancy	5x – 50x
Estrogen-progestogen therapies	2x – 9x
Cancer	4x – 7x
Myeloproliferative neoplasms	3x
Economy class syndrome (DVT on long haul flights)	2x – 4x
Obesity (BMI ≥30 Kg/m2)	2x – 3x