Prevalence of Factor V Leiden
The prevalence of Factor V Leiden varies significantly by ethnicity, with Caucasian Americans having the highest carrier frequency at approximately 5.3%, making it one of the most common monogenic disorders in this population. 1
Ethnic-Specific Prevalence Rates
The distribution of Factor V Leiden shows marked ethnic stratification:
- Caucasian Americans: 5.27% (95% CI, 4.42%-6.22%), with similar rates between men (5.53%) and women (4.85%) 1
- Hispanic Americans: 1.65-2.21% 2, 1
- African Americans: 0.87-1.23% 2, 1
- Asian Americans: 0.45% with some studies finding no mutations at all 2, 1
- Native Americans: 1.25% with some studies finding no mutations 2, 1
Clinical Significance
Factor V Leiden is the most common risk factor for venous thromboembolism, accounting for over 90% of activated protein C (APC) resistance cases. 2 The mutation causes an autosomal dominant trait that significantly increases thrombotic risk, with venous thromboembolism having an overall incidence of approximately 1/1,000 per year in the general population. 2
Key Clinical Pitfalls
The mutation segregates almost exclusively in populations with significant Caucasian admixture and is rare or absent in genetically distant non-European groups. 2 This ethnic stratification is critical when developing cost-effective screening programs—screening Asian Americans or Native Americans is likely to have extremely low yield given the near-zero prevalence in these populations. 2, 1
High-risk groups warranting consideration for screening include:
- Patients with prior venous thromboses 1
- Those with coexistent defects of anticoagulation 1
- Women at risk for postpartum thrombosis 1
- Women seeking oral contraceptives, particularly of Caucasian descent 1
The European and American Caucasian average allele frequency of 4.4% makes this one of the most prevalent monogenic disorders in this population. 2