F5 and Thromboembolism: The factor V Leiden mutation is caused by a single point mutation at nucleotide 1691, leading to an Arg/Gln amino acid exchange at this position is the most frequent inherited risk factor for thromboembolism in Caucasians with a prevalence of 5% in the general population.13 Higher frequency of this mutation in β-thalassemia patients and its association with deep venous thrombosis and cerebral venous and sinus thrombosis has been reported.38–40