An etiological evaluation was negative for viral infection [HBsAg, IgM HBc antibody, anti-hepatitis C virus (HCV) antibody, IgM-anti-hepatitis A virus (HAV) antibody, IgM anti-hepatitis E virus (HEV) antibody], autoimmune hepatitis [anti-nuclear antibody (ANA), anti-smooth muscle antibody (SMA), anti LKM1 antibody], Wilson disease (normal ceruloplasmin and no Kayser-Fleischer ring). Here, CD40LG is linked to viral infectious disease.