SOST and sclerosteosis: The marked prognathism displayed by our patient 2 resembles that observed in sclerosteosis (OMIM 269500), van Buchem disease (OMIM 239100), or craniodiaphyseal dysplasia (OMIM 122860), the most severe and lethal form of craniotubular dysplasia, which are all caused by SOST deficiency (Kim et al., 2011).