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ac·ro·ceph·a·lo·syn·dac·ty·ly | \ -ˌsef-ə-(ˌ)lō-sin-ˈdak-tə-lē \
: any of several genetic syndromes (such as Apert syndrome) that are present at birth and are characterized by premature closure of the cranial sutures resulting in malformations of the skull along with facial anomalies (such as widely spaced eyes)
Acrocephalosyndactyly is also typically marked by the presence of webbed or fused fingers and toes and broad thumbs and big toes. This disorder typically arises as a spontaneous mutation in which the defective gene is not present in either parent.