The prevalence of factor V R506Q mutation-Leiden among apparently healthy Lebanese

Resistance to activated protein C (APC) degradation caused by a specific po int mutation in the factor V (FV) gene, FV:R506Q or FV-Leiden, which replac es Arg506 with Gin at the APC cleavage site within the FV gene, is the most prevalent inherited caused of venous thrombosis. Recent reports suggested that the prevalence of FV-Leiden is high among Caucasians, and very low amo ng non-Caucasians, thereby suggesting that FV-Leiden has originated as a si ngle event in a primary focus. Insofar as FV-Leiden is associated with incr eased risk of thromboembolic diseases, coupled with its selective worldwide distribution, the aim of this study was to determine the prevalence of FV- Leiden in Lebanon and compare it with those of other countries of Caucasian and non-Caucasian origin. FV-Leiden was determined by PCR, followed by hyb ridization with specific wild-type and mutant DNA probes. By screening 174 healthy Lebanese subjects, 25 were shown to carry the FV-Leiden mutation, g iving an allele frequency of 7.4% and an overall prevalence rate of 14.4%. Of the 25 FV-Leiden carriers, 24 were in the heterozygous state while one w as In the homozygous states. No statistical difference in the FV-Leiden pre valence was noted with respect to age, gender, or sect. In addition to Leba non, which had the highest prevalence rate reported thus far (14.4%), a hig h prevalence of FV-Leiden was reported for Syria (13.6%), Greece-Cyprus (13 .4%), and Jordan (12.3%), an indication that the Eastern Mediterranean is t he primary focus of FV-Leiden mutation. The high prevalence of FV-Leiden in Lebanon suggests that screening for this mutation must be considered for t hose with a family history, and/or those with additional risk factors for v enous thrombosis. (C) 2000 Wiley-Liss, Inc.