Thrombophilia | Notion

Causes

Gain of function polymorphisms

factor V Leiden (activated protein C resistance): most common cause of thrombophilia
prothrombin gene mutation: second most common cause

Deficiencies of naturally occurring anticoagulants

The table below shows the prevalence and relative risk of venous thromboembolism (VTE) of the different inherited thrombophilias:

Condition	Prevalence	Relative risk of VTE
Factor V Leiden (heterozygous)	5%	4
Factor V Leiden (homozygous)	0.05%	10
Prothrombin gene mutation (heterozygous)	1.5%	3
Protein C deficiency	0.3%	10
Protein S deficiency	0.1%	5-10
Antithrombin III deficiency	0.02%	10-20

Antiphospholipid syndrome

Drugs