IL28B polymorphism (rs12979860) associated with clearance of HCV infection in Poland: Systematic review of its prevalence in chronic hepatitis C patients and general population frequency

BackgroundA common single nucleotide polymorphism (rs12979860) of the interleukin-28B (IL28B) gene is strongly associated with spontaneous and treatment-related eradication of HCV infection. In this study we estimated rs12979860 genotypes distribution among chronic hepatitis C patients in Poland using a systematic review of published studies and compared this data with the prevalence of rs12979860 variants of IL28B in representative sample of the Southern Poland population.MethodsSystematic review on rs12979860 variant prevalence in the Polish chronic HCV subjects was performed. Additionally, age- and gender-stratified population sample was recruited from inhabitants of Kraków using a randomized municipal census data, DNA samples available for 538 individuals were genotyped using a real-time PCR method.ResultsThe frequency of homozygotes TT was from 15 to 27% and carriers of unfavorable T alleles (genotypes CT and TT) were present in 70–80% of chronic HCV subjects. In the general population, 47% individuals were CC homozygous, 42% CT heterozygous and 11% TT homozygous. The population frequency of T allele was 0.318 (95% CI: 0.291–0.347) and the variant was in Hardy–Weinberg equilibrium. Distributions of IL28B genotypes in chronic HCV patients were characterized by a departure from the genetic equilibrium and differed significantly from the random population sample.ConclusionsEvents of spontaneous viral clearance can fully explain differences between genotype distributions in general population and chronic HCV subjects and a departure from the genetic equilibrium. This is the first study estimating the prevalence of IL28B rs12979860 SNP in the Southern Poland population based on a random representative sample.