High prevalence of prothrombin G20210A mutation among patients with deep venous thrombosis in Lebanon

Abstract number: P1182

Taher A., Abou Mourad Y., Khalil I., Abou-Merhi T., Shamseddine A., Bazarbachi A.

American University of Beirut-Medical Center, Lebanon

Factor V Leiden is the most common genetic risk factor for deep venous thrombosis (DVT). We have previously shown a high prevalence of factor V Leiden mutation among healthy individuals and patients with DVT in Lebanon. Prothrombin G20210A mutation has been described as the second most frequent genetic risk factor for DVT with a reported frequency of heterozygotes of 4.8%. On the other hand, the geographic distribution of this 20210 G to A prothrombin variant among healthy individuals varied from 0.7 to 4.0% with an overall prevalence estimate of 2.0%. This mutation is more frequent in southern Europe as compared to northern Europe and is very rare in Asia and Africa. We tested 100 healthy Lebanese individuals from all Lebanese communities and regions and 40 consecutive Lebanese patients with DVT admitted to the American University of Beirut-Medical Center. Total genomic DNA was extracted from peripheral blood mononuclear cells after informed consent and submitted to PCR using factor II specific primers. Prothrombin G20210A mutation was assessed by loss of cleavage site for Hind III restriction enzyme which allows the distinction between heterozygous and homozygous states. We found a prevalence of factor II G20210A mutation of 3% among healthy subjects (none was homozygous). No ethnic or regional variation was found. Among patients with DVT, 5 (12.5%) had factor II G20210A muation (all were heterozygous) (Table 1). When risk factors for DVT were taken into account, 30% of the patients had a positive family history, 33% had recurrent DVT and 54% had an age < 50 years. Positive family history was not statistically associated with an increased risk for factor II G20210A mutation (25% vs. 7%; P = 0.06) probably because of the small sample size but recurrent DVT (31% vs. 4%; P = 0.04) and young age below 50 years (23% vs. 0%; P = 0.01) were significantly associated with an increased risk for factor II G20210A mutation. These results confirm the previously reported prevalence of factor II G20210A mutation among healthy individuals but show a significantly higher prevalence among patients with DVT in Lebanon as compared to patients with DVT in other geographic areas. This high frequency, together with homozygous factor V Leiden state suggest a mandatory screening for factor V Leiden and factor II G20210A mutations in patients with DVT and their relatives.

Table 1.  Frequency of factor II G20210A mutation among healthy individuals and patients with deep venous thrombosis in Lebanon.