Chemokine Receptor CCR5 Gene Polymorphism and Clinical Outcomes in Individuals with Chronic Hepatitis C and Shistosoma Mansoni Infection

Chemokine receptor CCR5 is a receptor for proinflammatory chemokines which plays key roles in host responses, especially to viruses. The 32-bp deletion mutation in the CCR5 coding region (CCR5?32) abolishes the receptor from the cell surface, and in homozygous individuals there is no functional CCR5. Homozygosity for this deletion (CCR5?32/?32) is found in 1% of Caucasians, who are protected against HIV infection, whereas the heterozygous state (CCR5?32/WT) is found in 10% of Caucasians, who show slower HIV progression. A number of studies of Hepatitis C Virus (HCV) infection have explored the association between the CCR5Δ32 mutation and HCV susceptibility and severity in people with and without schistosomiasis. Discrepant results have been reported, with positive, negative, or zero effects of the CCR5Δ32 mutation on liver fibrosis or inflammation, response to treatment, or spontaneous viral clearance in patients with HCV infection. This article summarizes the findings of these studies and discusses their limitations and discrepancies. Much work remains to be done to fully elucidate the association between the CCR5?32 mutation and HCV outcomes, and to identify the mechanisms of this association in different groups of patients groups in different localities. A generalizable association between the CCR5?32 mutation and HCV disease would provide new insights for the development of therapeutic options.