Sclerostin (SOST) is a negative regulator of bone growth that acts through inhibition of Wnt signalling and bone formation []. Mutations in the SOST gene have been linked to several bone diseases, such as sclerosteosis 1 (SOST1)3 [], van Buchem disease (VBCH) []and craniodiaphyseal dysplasia autosomal dominant (CDD) [].
This sclerostin family consists of sclerostin and sclerostin domain-containing protein 1. Sclerostin (SOST) is thought to suppress bone formation. Mutations of the SOST gene lead to sclerosteosis, a progressive sclerosing bone dysplasia with an autosomal recessive mode of inheritance. Radiologically, it is characterised by a generalised hyperostosis and sclerosis leading to a markedly thickened and sclerotic skull, with mandible, ribs, clavicles and all long bones also being affected. Due to narrowing of the foramina of the cranial nerves, facial nerve palsy, hearing loss and atrophy of the optic nerves can occur. Sclerosteosis is clinically and radiologically very similar to van Buchem disease, mainly differentiated by hand malformations and a large stature in sclerosteosis patients []. Sclerostin domain-containing protein 1, also known as USAG1, is a bone morphogenetic protein antagonist [].
