Apert syndrome is a form of acrocephalosyndactyly, a congenital disorder characterized by malformations of the skull, face, hands and feet. It is classified as a branchial arch syndrome, affecting the first branchial (or pharyngeal) arch, the precursor of the maxilla and mandible. Disturbances in the development of the branchial arches in fetal development create lasting and widespread effects.
In 1906, Eugène Apert, a French physician, described nine people sharing similar attributes and characteristics. Linguistically, “acro” is Greek for “peak”, referring to the “peaked” head that is common in the syndrome. “Cephalo”, also from Greek, is a combining form meaning “head”. “Syndactyly” refers to webbing of fingers and toes. In embryology, the hands and feet have selective cells that die, called selective cell death or apoptosis, causing separation of the digits. In the case of acrocephalosyndactyly, selective cell death does not occur and skin, and rarely bone, between the fingers and toes fuses. The cranial bones are affected as well, similar to Crouzon syndrome and Pfeiffer syndrome. Craniosynostosis occurs when the fetal skull and facial bones fuse too soon in utero, disrupting normal bone growth. Fusion of different sutures leads to different patterns of growth on the skull. Examples include: trigonocephaly (fusion of the metopic suture), brachycephaly (fusion of the coronal suture and lambdoid suture bilaterally), dolichocephaly (fusion of the sagittal suture), plagiocephaly (fusion of coronal and lambdoidal sutures unilaterally), and oxycephaly or turricephaly (fusion of coronal and lambdoid sutures).
Results of postmortem studies suggest that skletal deficiencies in the Apert face results from reduced growth of the cranial base , which leads to premature fusion of the midline sutures from the occiput to the anterior nasal septum . Results of some studies suggest that synostosis of the sphenoid bone to the adjacent vomer may be a factor. Apert first described the syndrome as a combination of multiple physical findings, including severe cranial vault deformities , syndactylism, mental retardation , and blindness. It is known that the craniofacial skletal abnormality of Apert syndrome is complex and includes fusion of the coronal sutures and abnormal formation or fusion of the anterior cranial base and midface sutures. In addition , the syndrome is characterised by four limb symmetric complex syndactylies of the hands and feet. Fusion or malformation of other joint including the elbows and shoulders , offen occurs.