en 23407797 Irritable Bowel Syndrome (IBS) is a functional gastrointestinal disorder, characterized by recurrent abdominal pain and altered bowel habits. This study was performed to investigate the important role of interleukin-12 (IL-12) in intestinal inflammation. For this study seventy one patients with IBS and 140 controls were investigated. The allele and genotype frequencies of IL-12 C(-1188)A were determined using polymerase chain reaction with sequence-specific primers. The allele A was more common that the allele C in both groups of patients and controls. There was not any significant difference on IL-12 alleles and genotypes between patients and controls. The AA genotype was the most common genotypes, which was seen in 57.4% of the patients and 51.4% of the controls (p=0.53). Although frequency of the CC genotype in the control group was lower than the patient group, this difference was not significant (5.7% vs. 11.5%, respectively, p=0.16). Considering the lack of association between IL-12 C(-1188)A polymorphism and IBS, this cytokine gene polymorphism may not have significant role in the pathophysiology of disease. Genetic polymorphism, Interleukin-12, Irritable bowel syndrome 45 48 https://www.ajmb.org/En/Article.aspx?id=52 https://www.ajmb.org/PDF/En/FullText/52.pdf ElhamBarkhordariMolecular Immunology Research Center, Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran178Ali AkbarAmirzargarMolecular Immunology Research Center, Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran179NaserEbrahimi-DaryaniDepartment of Gastroenterology and Hepatology, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran180MahdiMahmoudiMolecular Immunology Research Center, Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran181BitaAnsaripourMolecular Immunology Research Center, Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran182MaryamAlighardashiMolecular Immunology Research Center, Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran183Hamid RezaAhmadi-AshtianiBiochemistry and Nutrition Department, Zanjan University of Medical Sciences, Zanjan; and Clinical Biochemistry Department, School of Medical Science, Tarbiat Modarres University, Tehran, Iran184MohammadBashashatiGastrointestinal Research Group, University of Calgary, Calgary, Alberta, Canada185NimaRezaeiResearch Center for Immunodeficiencies, Pediatrics Center of Excellence, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran186