Sclerostin is a glycoprotein produced by osteocytes, which is thought to play an important role in bone's adaptive response to mechanical loading, acting within the local bone microenvironment to suppress bone formation.1 The sclerostin antibody romosozumab has recently been found to increase bone mineral density (BMD) and reduce fracture risk,2, 3 establishing sclerostin as an important drug target for osteoporosis. This evidence concerns the gene SOST and osteoporosis.