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

Resistance to activated protein C (APC) degradation caused by a specific point mutation in the factor V (FV) gene, FV:R506Q or FV-Leiden, which replaces Arg506 with Gln 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 among non-Caucasians, thereby suggesting that FV-Leiden has originated as a single event in a primary focus. Insofar as FV-Leiden is associated with increased 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 hybridization with specific wild-type and mutant DNA probes. By screening 174 healthy Lebanese subjects, 25 were shown to carry the FV-Leiden mutation, giving 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 was in the homozygous states. No statistical difference in the FV-Leiden prevalence was noted with respect to age, gender, or sect. In addition to Lebanon, which had the highest prevalence rate reported thus far (14.4%), a high 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 the primary focus of FV-Leiden mutation. The high prevalence of FV-Leiden in Lebanon suggests that screening for this mutation must be considered for those with a family history, and/or those with additional risk factors for venous thrombosis.