Genetic variation in interleukin 28B and correlation with chronic hepatitis B virus infection in Saudi Arabian patients

Background & Aims: Several genome-wide association studies have shown that genetic variations in the chromosomal region containing interleukin-28B (IL28B) gene are associated with response to treatment in hepatitis C virus (HCV) infection. This study was conducted to examine the role of genetic variations in IL28B on disease progression in Saudi Arabian patients chronically infected with hepatitis B virus (HBV). Methods: The study included 1128 subjects divided into four categories; 304 clearance subjects, 518 inactive carriers, 212 active carriers and 94 cirrhosis/HCC. Results: Three single nucleotide polymorphisms (SNPs), rs12979860 (OR = 1.307; 95% CI 1.046-1.634, chi(2) = 5.57 and P = 0.0183), rs12980275 (OR = 0.642; CI 0.517-0.798, chi(2) = 16.17 and P = 0.0001) and rs8105790 (OR = 0.746; CI 0.592-0.941, chi(2) = 6.12 and P = 0.0133), were found to be strongly associated with HBV clearance. The frequency of the G allele of rs12980275 and the C allele of rs8105790 were found to be more in clearance group than in patients and could contribute to protection against the disease. On the other hand, only rs12979860 showed significant difference in distribution when inactive group was compared to other groups (OR = 1.285; CI 1.030-1.603, chi(2) = 4.95, P = 0.0261). No significant association was evident for any of the variants when active carriers were compared to cirrhosis/HCC patients. Haplotype analysis showed that a combination of A-T-T-G of rs12980275, rs8105790, rs8099917, and rs7248668, respectively, was associated with clearance of the virus (frequency = 67.5% and P = 0.015). Conclusion: genetic variations in IL28B gene region may influence the clearance of HBV infection.