CYBA and chronic hepatitis C virus infection: Thus, given the important contribution of the NADPH oxidase system to the oxidative stress induced by HCV infection, the aim of the present study was to evaluate association of two single nucleotide polymorphisms (SNPs) in the genes encoding NOX4 and p22phox (CYBA) with metabolic and histological variables in patients with chronic hepatitis C. NOX4 rs3017887 was chosen because it was the most informative SNP (able to capture 12 out of 124 SNPs with minor allele frequency of at least 0.05) from a haplotype block comprised of four SNPs possibly associated with oxidative burden [11].