Tehran University of Medical Sciences International Journal of Hematology-Oncology and Stem Cell Research 2008-2207 9 4 2016 02 09 198 202 EN Fereshteh Maryami Biotechnology Research Center, Department of Molecular Medicine, Pasteur Institute of Iran, Tehran, Iran Azita Azarkeivan Pediatric Hematology Oncology, Transfusion Research center, High Institute for Research and Education in Transfusion Medicine, Department of Thalassemia Clinic, Tehran, Iran Mohammad Sadegh Fallah Kawsar Human Genetics Research Center, Tehran, Iran Sirous Zeinali Iranian Molecular Medicine Network, Biotechnology Research Center, Pasteur Institute of Iran, Pasteur St, Tehran, IranKawsar Human Genetics Research Center, Tehran, Iran 2015 10 17 2015 10 17 Background: Thalassemia syndromes are the most prevalent single gene disorders in Iran. This study aimed to evaluate the effect of different types of beta-globin gene mutations, co-inheritance of alpha-globin gene mutations and/or Xmn1 SNP on disease phenotype in a large cohort of Iranian patients. Subjects and Methods: In total, 433 patients were clinically classified into β-thalassemia major (TM) or intermedia (TI). Multiplex PCR, ARMS-PCR, RFLP-PCR and DNA sequencing were performed to identify both α- and β-globin gene mutations and Xmn1 polymorphism as well. All data were compared and analyzed by SPSS software in TM and TI groups consequently. Results: A total of 39 different β-globin mutations were identified. Among them, the most common were IVS IInt1 (40.33%) followed by IVS Int5 (9.56%), C30 (7.22%) and Fr8-9(7%). All patients were subjected to evaluate common α-globin gene deletions. The patients inherited concomitant mutations of α- and β-globin, showed no clinical modifications compared with those who had only β-globin mutation. The TI patients showed a significant increase in frequency of both heterozygous and homozygous form of the Xmn1 polymorphism. It was also found that β0/β0 genotype patients, inherited the Xmn1 polymorphism required lesser blood transfusion. Conclusion: No significant differences were observed, on the severity of disease, between patient's inherited defective α- and β-globin genes and ones with just β-globin gene mutation. Taking the results of this research into account, Xmn1 polymorphism can be considered as an important genetic factor modulating the severity of disease. https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/view/471 https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/download/471/444