In patients with hepatocellular carcinoma, miR-122 and SIRT6 negatively regulate each other and miR-122 over-expression or down-regulation leads to a decrease or induction of SIRT6 protein levels, respectively, and the SIRT6-miR-122 correlation may serve as a biomarker for liver cancer prognosis [139]. The gene discussed is SIRT6; the disease is liver cancer.