Factor V R506Q mutation-Leiden: An independent risk factor for venous thrombosis but not coronary artery disease

Background: A specific point G-A transition at nucleotide position 1691 in the factor V (FV) gene, FV-Leiden, was associated with increased risk of ve nous thromboembolism (VTE). Insofar as the association of FV-Leiden with co ronary artery disease (CAD) remains poorly defined, the aim of this study w as to determine the prevalence of FV-Leiden in a sample of 68 VTE patients, 69 CAD patients, and 192 randomly selected healthy subjects. Methods: Total genomic DNA was extracted from the peripheral blood of study subjects and was used for PCR analysis. The presence (or absence) of FV-Le iden was assessed by PCR using primers flanking the mutant site (nt 1691), followed by hybridization with wild-type ('G') and mutant ('A') biotinylate d DNA probes; detection was by DNA enzyme immunoassay (DEIA). Results: While the prevalence of FV-Leiden in CAD patients was not statisti cally different from that of healthy subjects (14.5 % vs. 15.1 %; P=0.890, odds ratio 0.95; 95 % confidence interval 0.43-2.06), a significant increas e in FV-Leiden prevalence was seen in VTE patients (70.6 % in VTE patients; P <0.001, odds ratio 13.4, 95 % confidence interval 6.9-25.8). Of the 48 V TE patients who tested positive for FV-Leiden, 42 were heterozygotes (G/A), while 6 were homozygotes (A/A) (allele frequency 0.397). All 10 CAD patien ts positive for FV-Leiden were heterozygote carriers (allele frequency 0.07 2). While gender was not a factor in FV-Leiden expression, higher prevalenc e in FV-Leiden was seen in younger (less than or equal to 45 years) VTE pat ients (38/51 vs. 10/17). Conclusion: FV-Leiden is a major inherited risk factor for VTE, with a peak incidence in younger patients, but does not appear to play any role in CAD pathogenesis in the population studied.