IFNG and infection: A higher risk of infection and the frequency of the TGF-β1 -509C/T polymorphism genotype were linked to HCV infection. In the control and HCV groups, plasma levels of IFN-γ were higher in TT genotype carriers. The HCV group and TT genotype carriers had the highest TGF-β1 levels. TGF-β1 levels were higher in those with cirrhosis.