BACKGROUND AND OBJECTIVE: Infection with hepatitis B virus is a major cause of chronic liver diseases and variations within cytokine genes may affect the host immune response to hepatitis B infection. This study was designed to investigate whether IL-20 rs1400986 C/T single nucleotide polymorphism is involved in the progression of chronic hepatitis B infection.

METHODS: In this case-control study a total of 150 chronic hepatitis B patients (Anti-HBc Ab positive and HBsAg positive for more than 6 months) and 146 healthy subjects (Anti-HBc Ab and HBsAg negative) among people who were referred to Tehran Taleghani hospital during 2003 to 2005, were examined for differences in genotype and allele frequencies in this case-control study. Polymerase Chain Reaction- Restriction Fragment length Polymorphism (PCR-RFLP) method was applied for analyzing the polymorphism site.

FINDINGS: Genotypes Frequency in patients group were CC 32.0% and TT 4.0% in comparison to CT 28.1% and TT 2.7% in control group; however no statistically significant difference was observed in the frequency of IL-20 gene polymorphism (rs1400986) between chronically infected patients and healthy controls for neither allele (P=0.549) nor genotype (p=0.599) frequencies.

CONCLUSION: No association was detected between rs1400986 single nucleotide polymorphism within IL-20 gene and chronic hepatitis B infection; thus, this polymorphism appears to have no influence on susceptibility to chronic hepatitis B.