The possible influence of this mechanism on the development of osteoporosis in haemophilia is suggested by the studies of Chirstforidis et al. [36], which showed a decrease in the level of osteoprotegerin (OPG) and an increase in the soluble activator of the nuclear ligand receptor factor κB (sRANK-L) compared to the control group. The gene discussed is TNFRSF11B; the disease is hemophilia.