Distribution of IL28B Genotypes in Iranian Patients with Chronic Hepatitis C and Healthy Individuals

BACKGROUND: IL28B polymorphism is recognized as one of the most prominent predictors of hepatitis C spontaneous and treatment-induced clearance. Interestingly, the favorable genotypes of IL28B are found to be more frequent in Asian ethnicity than Caucasian and African populations, respectively. A few studies reported that there is a mysterious association between the IL28B polymorphism and the hepatitis C virus (HCV) genotype in patients with chronic hepatitis C but they did not give any reason for this phenomenon. OBJECTIVES: The foremost purpose of this study was to compare the distribution of IL28B genotypes between Iranian healthy individuals and patients with chronic hepatitis C. PATIENTS AND METHODS: In this study, 921 patients with chronic hepatitis C and 142 healthy individuals were included. The IL28B rs12979860 and rs8099917 polymorphisms were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. RESULTS: The frequency of IL28B rs12979860 CC, CT, and TT genotypes in chronic hepatitis C patients was 38%, 48.8%, and 13.2% and in healthy individuals was 43.7%, 48.6%, and 7.7%. Also, the frequency of IL28B rs8099917 TT, GT, and GG genotypes in chronic hepatitis C patients was 58.3%, 37.1%, and 4.6% and in healthy individuals was 64.1%, 32.4% and 3.5%. The differences in the distribution of IL28B rs12979860 and rs8099917 genotypes between patients with chronic hepatitis C and healthy individuals were not statistically significant. When we compared the distribution of IL28B genotypes between the healthy group and the HCV infected patients by HCV genotype, we found 9.8% higher frequency of rs12979860 CC genotype in the healthy individuals than HCV genotype 1 infected patients (P = 0.03) however there was no significant difference in the distribution of rs12979860 genotypes between the healthy and HCV genotype 3 infected groups (P = 0.46). CONCLUSIONS: It seems that the impact of IL28B polymorphism on the spontaneous clearance of HCV genotype 1 is more prominent than HCV genotype 3 which results in the observation of higher rs12979860 C allele frequency in chronic hepatitis C patients with HCV genotype 3 than HCV genotype 1.