Fibrosis Progression in HCV Carriers with Mild Hepatitis Who Possess the High-Repetition Variant of the DRD4 Gene, a Genetic Marker for Binge-Drinking and Risk-Seeking Behavior: A Longitudinal Study

Background: Alcohol is a major determinant of the outcome of chronic hepatitis C virus (HCV) infection, but self-reported drinking habits lack reliability. We hypothesized that carriage of high-repetition variants (HRV) of the variable number of tandem repeats (VNTR) in exon III of the dopamine receptor D₄ gene, linked to binge-drinking and risk-seeking behavior, might be a proxy measure of alcohol consumption, and aimed to verify whether it may affect histologic outcome. Methods: A cohort of HCV patients with normal or near-normal aminotransferases (N = 128) underwent a liver biopsy as part of diagnostic work-up. None admitted to exceed low-risk alcohol consumption; most (90/128, 70%) described themselves as teetotalers. They received advice on abstaining from alcohol, but not antiviral treatment. After a median follow-up period of 10 years, all underwent a second liver biopsy. HRV allele frequencies were compared with those of a group of healthy blood donors (N = 128) and related to liver histology. Results: HRV allele frequencies were 0.19 in patients and 0.16 in controls (p = 0.182). In the subgroup of patients who admittedly had consumed alcohol, 20/38 (53%) carried HRV, in comparison with 27/90 patients (30%) who had denied to consume alcohol (p = 0.026 by Fisher's exact test). Carriage of HRV was associated with higher histologic grade (p = 0.002) and stage (p = 0.009) at the final biopsy. At multivariate analysis, among a set of variables also including viral genotype, viral load, body mass index, gender, and history of alcohol consumption, only age (OR = 1.06, 95% CI 1.02 to 1.11) and HRV (OR = 3.13, 95% CI 1.28 to 7.68) were independent predictors of significant fibrosis at the end of follow-up. Conclusions: The link between HRV carriage and histologic outcome in a subgroup of HCV patients at low risk of progression underlines the need for intense scrutiny of alcohol habits in hepatitis C.