Tehran University of Medical Sciences Basic & Clinical Cancer Research 2228-6527 3 1 2011 02 01 36 44 EN Ali-akbar Amirzargar Molecular Immunology Research Center, Tehran University of Medical Sciences Majid Mahmoodi Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences. Hedayat Nahvi Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences Mehdi Mahmoodi Molecular Immunology Research Center, Tehran University of Medical Sciences Zahra Safari Islamic Azad University, Young Researcher Club, Pishva-Varamin Branch, Iran Amir Kasaian Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences K Divsalar Neuroscience Research Center, Kerman University of Medical Sciences, Kerman Bijan Nahavandian Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences Abbas Jafari Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences Dariush Heydar-Nasab Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences Batool Moradi Molecular Immunology Research Center, Tehran University of Medical Sciences Mohammad-Ali Mohagheghi Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences 2011 09 06 2011 09 06 Background: The study aimed to examine the association between human leukocyte antigen (HLA) class II allele frequencies and breast cancer in Iranian women. Methods: A total of 100 patients with pathologically proven breast cancer who referred to Cancer Institute were randomly selected and compared with a group of age matched healthy blood donors (n = 80). HLA class II alleles were determined by amplification of DNA followed by HLA-typing using sequence-specific primer (SSP) for each allele. Results: The frequency of HLA-DQA1*0301 (P=0.001, OR=3.4) and HLA-DRB1*1303 (P=0.02, OR=2.3) among breast cancer patients was significantly higher than those in control group. HLA-DQA1*0505 (P=0.003, OR=0.4), HLA-DRB1*1301 (P=0.002, OR=0.12) and HLA-DQA1*0101 (P=0.01, OR=0.21) alleles showed negative association with breast cancer. Conclusion: The findings suggest that HLA-DQA1*0301 allele is mainly associated with increased risk of breast cancer in Iranian female patients. HLA-DQA1*0505 and HLA-DRB1*1301 alleles are suggested as protective genetic factors against breast cancer. The findings confirm that specific alleles of HLA class II influence breast cancer risk. https://bccr.tums.ac.ir/index.php/bccrj/article/view/6 https://bccr.tums.ac.ir/index.php/bccrj/article/download/6/6