Overexpression of SOST gene in mice leads to low bone mass as a result of reduction in osteoblast activity [29]; on the contrary, loss-of-function mutations of SOST gene lead to van Buchem disease and sclerosteosis, diseases distinguished by osteoblast hyperactivity and consequent increased bone density [54]. The gene discussed is SOST; the disease is hyperostosis corticalis generalisata.