Furthermore, this study contains an additional case series, which provides further evidence to justify the use of plasma sPD-1 as a marker of immunity for chronic hepatitis B. Because the availability of detailed information on viral and clinical features, including viral load updated at multiple time points, we could evaluate and exclude important confounding variables, as well as comprehensively examine the effect of sPD-1 on the key steps towards HCC. The gene discussed is HOXD13; the disease is chronic hepatitis B virus infection.