Pfeiffer syndrome

Pfeiffer syndrome is a rare genetic disorder characterized by the premature fusion of certain bones of the skull (craniosynostosis), which prevents further growth of the skull and affects the shape of the head and face. It is named after Rudolf Arthur Pfeiffer (1931-) who, in 1964, described a list of features that included a coronal synostosis, turribachycephaly (high prominent forehead) and maxillary hypoplasia (eyes with a bulging appearance due to small underlying cheek bones). Pfeiffer syndrome affects about 1 in 100,000 births.

Genetics
Pfeiffer syndrome is strongly associated with mutations of Fibroblast growth factor receptor 1 and 2. These receptors are important for normal bone development.

Presentation
Many of the characteristic facial features that Pfeiffer described in Pfeiffer syndrome result from the premature fusion of the skull bones. The head is unable to grow normally, which leads to eyes that appear to bulge (proptosis) and are wide-set (hypertelorism), an underdeveloped upper jaw, and a beaked nose. About 50 percent of children with Pfeiffer syndrome have hearing loss (see hearing loss with craniofacial syndromes), and dental problems are also common. Broad thumbs and toes are extra-cranial features of this syndrome.

Classification
Pfeiffer syndrome is divided into three subtypes.
 * Type 1 or "classic" Pfeiffer syndrome has symptoms as described above. Most individuals with type 1 have normal intelligence and a normal life span.
 * Types 2 and 3 are more severe forms of Pfeiffer syndrome, often involving problems with the nervous system. Type 2 is distinguished from type 3 by more extensive fusion of bones in the skull, leading to a "cloverleaf" shaped head.