Carpenter syndrome, also called acrocephalo-polysyndactyly type Ⅱ, is an autosomal recessive dominant inherited disease with craniosynostosis, characterized by a combination of craniosynostosis, polysyndactyly, obesity, and other congenital malformations. CS will result in some complications including mental retardation, intracranial hypertension. To date, the majority of CS is caused by mutations in the RAB23 gene, which encodes a small GTPase of the Rab superfamily. Rab acts as an essential negative regulator of the Sonic hedgehog signaling pathway. The mutation of RAB23 in CS result in the structure and function of the protein, which probably through perturbation of signaling by hedgehog. However, the pathogenesis is not exactly clear. Some of the CS is caused by mutations in multiple EGF-like-domains (MEGF8).