Pfeiffer syndrome is caused by mutations in two genes known as FGFR1 and FGFR2 - where the initials stand for fibroblast growth factor receptor. Each of these genes codes for a protein that is a member of the fibroblast growth factor receptor family.
The proteins have many roles in the body including cell signalling, and during embryogenesis they signal immature cells to form bone cells. However, if the genes are mutated the protein function is altered and the signalling is protracted which causes the bones cells to mature earlier than they would otherwise. This also promotes the premature fusion of skull bones.
There are three subtypes of Pfeiffer syndrome - types 1,2, and 3. Individuals with type 1 tend to have normal intelligence and enjoy a normal lifespan.
Types 2 and 3 are more severe forms of the disease and the premature fusion of skull bones can limit brain growth which can lead to delayed development and neurological problems.