Further, premature ossification in fam20b mutants provided a new etiology for Raine syndrome, a human disease resulting from mutations in FAM20C. Also known as osteosclerotic bone dysplasia, Raine syndrome patients have craniofacial defects such as low nasal bridge and midfacial hypoplasia indicative of defects in growth at synchondroses, as well as short and overossified long bones in newborns (Figure 5C). The gene discussed is FAM20C; the disease is lethal osteosclerotic bone dysplasia.