Tehran University of Medical Sciences International Journal of Hematology-Oncology and Stem Cell Research 2008-2207 6 2 2012 06 15 17 21 Mehrdad Payandeh Medical Biology Research Center, Kermanshah University of Medical Science, Kermanshah, Iran. Hoshang Yousefi Blood Transfusion Research Center, High Institue for Research and Education in Transfusion Medicine,Science, Kermanshah, Iran. Mohammad Erfan Zare Medical Biology Research Center, Kermanshah University of Medical Science, Kermanshah, Iran Atefeh Nasir Kansestani Medical Biology Research Center, Kermanshah University of Medical Science, Kermanshah, Iran; Zohreh Rahimi Medical Biology Research Center, Kermanshah University of Medical Science, Kermanshah, Iran Darioush Pourmand Department of Medical Lab Science, Paramedicine Faculty, Kermanshah University of Medical Science, Kermanshah, Iran Amir Hossein Hashemian Department of Biostatistics, Faculty of Public Health, Kermanshah University of Medical Science, Kermanshah, Iran Mahmood Aeinfar Student Research Committee, Electronic Department, Faculty of Technology, Islamic Azad University,Kermanshah, Iran Mehrnoush Aeinfar Medical Biology Research Center, Kermanshah University of Medical Science, Kermanshah, Iran. Farhad Shaveisi Zadeh Departments of Medical Genetics, Faculty of Medicine, Sahid Beheshti University of Medical Science, Kermanshah, Iran 2015 10 01 Introduction: The main inhibitors of coagulation pathway are antithrombin (AT), protein C and protein S. These inhibitors are necessary to prevent thromboembolism. Hereditary deficiency of inhibitors is the main cause of alteration in balance between the anti-clotting and the formation of thrombin. Patients with this abnormality are susceptible to venous thromboembolism (VTE). Two major clinical manifestation of VTE are deep vein thrombosis (DVT) and pulmonary embolism (PE). The aim of present study was to investigate the frequency of coagulation inhibitor proteins and resistance to activated protein C (APC-R) in DVT patients from Kermanshah province of Iran with Kurdish ethic background. Materials and methods: We investigated all patients with thrombophilia who referred to Iranian Blood Transfusion Organization from May 2011 to March 2012. The levels of protein C, protein S and antithrombin were measured using STAGO kits, France (Diagnostica Stago) and the APC-R level was detected using Pefakit® kit. Results: After excluding patients with confounding factors, 54 patients were remained. Our results showed that acquired risk factors are the most common causes of DVT in the present study. In our study protein C deficiency was found to be the most hereditary risk factor followed in frequency by APC-R. Also, in 16 patients (29.6%) there were combined hereditary risk factors with deficiency in 2 or 3 factors. Conclusion: Our results showed protein C deficiency was the prevalent cause of DVT in our patients. Also, different pattern of hereditary risk factors in our patients compared to other regions of Iran could be attributed to different ethnic background of our patients. https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/view/330 https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/download/330/316