APA Dictionary of Psychology

an inherited disorder marked by premature fusion of the cranial bones, causing a skull deformity (see craniosynostosis syndrome). Individuals also have facial deformities with protruding, widely spaced eyes (which often show signs of strabismus), large thumbs, and large great toes. Some affected individuals have below average intelligence. The syndrome is inherited as a dominant trait (see acrocephalosyndactyly). Also called acrocephalosyndactyly Type V. [Emil Pfeiffer (1846–1921), German physician]