en Adults Hematology & Oncology Adults Hematology & Oncology پژوهشي Original Article <div dir="ltr"></div> Background: Factor V Leiden, Prothrombin gene (G20210A) and MTHFR (C677T) polymorphism are the main biomarkers for evaluation of tendency for venous thromboembolism. We aimed to investigate the frequency of mutations in factor V Leiden, Prothrombin G20210A and MTHFR C677T and identify the genetic status for these mutations in patients with venous thrombosis.<br> Methods: This study was carried out in 312 patients with venous thrombosis who were referred to &ldquo;Thrombosis Clinical center&rdquo;, Imam Khomeini Hospital, Tehran, Iran and &ldquo;Sarvar Clinic&rdquo;, Mashhad, Iran. Identification of gene mutations was performed using PCR-restriction fragment length polymorphism (RFLP)-based method.<br> Results: The prevalence of Factor V Leiden mutation was 35.8%, while 8.9% of them were homozygous for AA allele and 26.9% had the GA allele in heterozygous state. The prevalence of MTHFR (C677T) mutation was 17.9% of which 7.1% had the TT mutant allele in homozygous and 10.8% had CT allele in heterozygous state. The prevalence of mutation in prothrombin gene G20210A was 8.9% with all cases heterozygous for GA mutant allele.<br> Conclusion: In our study from two referral centers for thrombotic disorders, the prevalence of mutations in gene encoding factor V Leiden was higher than Prothrombin 20210A and MTHFR C677T polymorphisms. Therefore, assay for factor V Leiden mutation has the first priority in the evaluation of patients with hereditary thrombophilia in these geographical regions.&nbsp; Venous thromboembolism, Factor V leiden, MTHFR C677T, Prothrombin G20210A, PCR-RFLP method 91 95 http://ijbc.ir/browse.php?a_code=A-10-387-2&slc_lang=en&sid=1 Mohsen Hamidpour mohsenhp@sbmu.ac.ir 10031947532846004945 10031947532846004945 No PhD in Hematology, Department of Hematology & Blood Banking , School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mohammad Ghorbani Sbmu_mohamad@yahoo.com 10031947532846004946 10031947532846004946 Yes MSc of Hematology and Blood Banking, Faculty member of Gonabad University of medical sciences, Gonabad, Iran. Mostafa Rezaei-Tavirani tavirany@yahoo.com 10031947532846004947 10031947532846004947 No Proteomics Research Center, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran Hamid Reza Niazkar hrn185@hotmail.com 10031947532846004948 10031947532846004948 No Medical Student, Student Research Committee, Gonabad University of Medical Sciences, Gonabad, Iran Mohammad Reza Managhchi m.managhchi@gmail.com 10031947532846004949 10031947532846004949 No Msc in Hematology and oncology, Thrombosis Disease Research Center, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran Masoud Shahrudian noormedlab@yahoo.com 10031947532846004950 10031947532846004950 No Doctor of Clinical laboratory scienses, Sarvar Clinic laboratory, Mashhad