Periostin has been observed to play a role in the development of craniosynostosis, as it is expressed in the domain of Twist1, forming both homodimers (T/T) and heterodimers with E2A E proteins (T/E) in the cranial sutures of Twist1+/− mice, and is altered by changes in Twist1 expression, which means there must be interplay between periostin and Twist1 in the cranial suture morphogenesis of Twist1+/− mice [11]. The gene discussed is TWIST1; the disease is craniosynostosis.