Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Craniosynostosis ?
    ### Response:
    Craniosynostosis is a birth defect of the skull characterized by the premature closure of one or more of the fibrous joints between the bones of the skull (called the cranial sutures) before brain growth is complete. Closure of a single suture is most common.
    