Apert syndrome, also known as acrocephalosyndactyly type I (ACS1), is a rare genetic disorder that is apparent at birth (congenital). The disorder is character-ized by distinctive malformations of the head that lead to distinctive facial features. In addition, the hands and/or feet may be webbed (syndactyly) and in some cases, mental retardation may also be present.
Among babies born with Apert syndrome, the fibrous joints between bones of the skull (sutures) close prematurely (craniosynostosis). The pressure of continued brain growth distorts various bones of the skull and the face. The skull is forced into one of several characteristic shapes. Often the head appears abnormally pointed at the top (acrocephaly). The distortion of the skull plates create changes in the facial bones leading to characteristic facial abnormalities, such as widely spaced eyes (ocular hypertelorism), abnormal protrusion of the eyes (exophthalmos), underdevelopment of midfacial regions (midface hypoplasia), and/or a narrow roof of the mouth (palate).
Malformations of the hands and feet may include unusually broad thumbs and great toes, short fingers, and/or partial to complete fusion (syndactyly) of certain fingers and toes (digits). Most commonly, there is complete fusion of bones within the second to the fourth fingers and the presence of a single common nail ("mitten-like" syndactyly).
In almost all instances, Apert syndrome results from new genetic changes (mutations) that appear to occur randomly for unknown reasons (sporadically). In rare cases, the disorder may be inherited as an autosomal dominant trait.