Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 15 4 2016 08 30 289 295 EN Shamsolmoulouk Najafi Dental Research Center, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Mahsa Mohammadzadeh Department of Orthodontic, Dental Branch, Islamic Azad University, Tehran, Iran Alireza Zare Bidoki Noncommunicable Diseases Research Center, Fasa University of Medical Sciences, Fasa, Iran AND Thrombosis Hemostasis Research Center, Tehran University of Medical Sciences, Tehran, Iran Ghasem Meighani Department of Pediatrics , School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Saeed Aslani Rheumatology Research Center, Tehran University of Medical Sciences, Tehran, Iran AND Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Mahdi Mahmoudi Rheumatology Research Center, Tehran University of Medical Sciences, Tehran, Iran Nima Rezaei Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran AND Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran AND Universal Scientific Education and Research Network (USERN), Tehran, Iran 2015 12 01 2016 02 29 Recurrent aphthous stomatitis (RAS) is known as the most common chronic disease of the oral cavity, which affects a range of 5-25% of the population. RAS appears to be associated with some human leukocyte antigen (HLA) class II alleles and haplotypes. This study attempts to survey the distribution of HLA-DRB and -DQB alleles among Iranian RAS patients and healthy controls. In order to evaluate the association of HLA-DR and DQ alleles and haplotypes, 54 patients with RAS and 100 unrelated healthy subjects as control group were investigated. Our data indicated that DRB1*13:17, DRB1*15:01, and DRB5*01 were significantly more frequent in RAS patients in comparison to controls. However, DRB3:01allele frequency was higher in the controls compared to the patients. The significantly frequent allele in the patients compared with the healthy subjects was HLA-DQB1*03:02. However, both HLA-DQB1*02:01 and HLA-DQB1*03:01 alleles were most frequent in the healthy individuals rather than the patients. The DRB*04/DQB1*03:01 and DRB*01:01/DQB1*02:01 haplotypes were significantly distributed in healthy subjects compared with patients. However, DRB*07:01/DQB1*03:02 haplotype was found to be significantly frequent in patients than controls. In respect of HLA genes, factors are involved in the incidence of RAS; various HLA-DRB and HLA-DQB1 alleles and the related haplotypes are suggested to be the three main RAS susceptibility factors in our population study. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/710 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/710/643