Supporting all those affected by craniosynostosis and rare carniofacial conditions.We are the leading UK charity supporting people with craniosynostosis and other rare craniofacial conditions. Craniosynostosis is a rare craniofacial condition where two or more plates of the skull prematurely fuse to each other, usually before birth. This results in the baby’s skull not growing properly and the newborn’s head shape being different at birth. The shape of the head may continue to change after birth as it grows.