Studies on TAQ1 polymorphism in the 3'untranslated region of IL-12P40 gene in HCV patients infected predominantly with genotype 3

Abstract

Host immunity plays an important role in viral persistence and progression of liver disease in HCV infected patients. IL-12 induces production of IFN-γ, a potent antiviral agent. IL-12 comprises two subunits; IL-p35 and IL-12p40, which are encoded by two different genes located on chromosome 3 and 5, respectively. Single nucleotide polymorphism at A1188C in the 3'UTR of IL-12p40 gene is associated with immune mediated diseases. Association of IL-12p40 A1188C polymorphism with the outcome of HCV infection was investigated in this study. Two hundred and fifty three histologically proven chronic hepatitis C patients (43±13 years, male:female: 185:68) and 380 matched controls were included. Genotyping was performed by RFLP and confirmed by direct sequencing. To assess correlation of immune gene polymorphism with severity of HCV-related liver disease, patients were divided into those with fibrosis score of < or=2 (mild) or > 2 (severe), and histological activity index (HAI) of=5 (mild) or >5 (severe). The distribution of A/A, A/C or C/C alleles in the controls was comparable to the patients. The distribution of C/C allele was significantly more common in patients with mild as compared to severe fibrosis (23.7% vs. 6.25%, P=0.004). No significant difference was observed for any of the genetic markers with HAI or with normal or raised alanine aminotransferase (ALT). These results show that the C/C allele of IL-12p40 gene could render genetic protection against development of severe liver disease in patients infected with HCV.