Pfeiffer syndrome is a rare genetic disorder characterized by premature fusion of certain skull bones (craniosynostosis), and abnormally broad and medially deviated thumbs and great toes. Most affected individuals also have an abnormal midface, with protruding eyes and conductive hearing loss. Three forms of Pfeiffer syndrome are recognized, of which types II and III are the more serious.
Pfeiffer syndrome is an autosomal dominant condition associated with mutations in the fibroblast growth factor receptor-2 (FGFR2) gene and the fibroblast growth factor receptor-1 (FGFR1) gene.
Pfeiffer syndrome is now known to be a member of a group of conditions caused by mutations in the FGFR genes including Apert syndrome, Crouzon syndrome, Beare-Stevenson syndrome, FGFR2-related isolated coronal synostosis, Jackson-Weiss syndrome, Crouzon syndrome with acanthosis nigricans and Muenke syndrome. (For more information on these conditions, please see the Related Disorders section below.