SOST and sclerosteosis: The biologic importance of sclerostin in regulating bone mass in humans is highlighted by two genetic disorders associated with markedly increased bone mass: sclerosteosis and van Buchem disease.(14–17) These findings, combined with the demonstration that sclerostin-deficient mice have increased bone mass,(18) have led to the development of antisclerostin neutralizing antibodies as a novel anabolic treatment for osteoporosis.(19)