For example, in mouse models of Twist1+/− craniosynostosis, the earliest detectable defect is the aberrant expression of Notch2, which is a marker of osteogenesis, and it is abnormally expressed in non-osteogenic suture mesenchymal regions in Twist1+/− mouse embryos at E12.5 (Yen et al., 2010). The gene discussed is TWIST1; the disease is craniosynostosis.