Osteoporosis is mainly caused by the upregulation of the receptor activator of the nuclear factor kappa (RANK)-RANK ligand (RANKL)-osteoprotegerin system, increased inflammatory cytokines, and inhibited bone formation by accumulated bilirubin and sclerostin and decreased insulin-like growth factor-1 in liver disease. The gene discussed is TNFRSF11B; the disease is osteoporosis.