SOX9 and orofaciodigital syndrome: Mouse models for OFD, as well as mutants that have similar phenotypes to OFD (Fuz−/−), have expanded areas of facial cartilage (as determined by increased expression of Sox9 and Col2a1, and Alcian Blue staining), concordant with increased levels of Ffg8 expression (Tabler et al., 2013; Zhang et al., 2011).