F5 and pulmonary embolism: It was seen that factor V Leiden mutation existed in 20% of patients with systemic vein thrombosis.22 Caprini et al. reported that there was factor V Leiden mutation in 17% of patients with deep vein thrombosis history and 27.3% of the patients with pulmonary embolism.22-24 Turello et al. detected heterozygous factor V Leiden mutation in 8.2% of the patients with RVO.25 In our study, while heterozygous factor V Leiden mutation was detected in five (12.5%) patients, homozygous mutation was not detected.