Craniofrontonasal syndrome is a rare condition characterized by the premature closure of certain bones of the skull (craniosynostosis) during development, which affects the shape of the head and face. The condition is named for the areas of the body that are typically affected: the skull (cranio-), face (fronto-), and nose (nasal).
In people with craniofrontonasal syndrome, the skull bones along , which is the growth line that goes over the head from ear to ear, closes early. These changes can result in an abnormally shaped head and distinctive facial features. The size and shape of facial structures may differ between the right and left sides of the face (facial asymmetry) in individuals with craniofrontonasal syndrome. Affected individuals may also have wide-set eyes (), eyes that do not point in the same direction (strabismus), involuntary eye movements (nystagmus), , a , an upper lip that points outward (called a tented lip), or with or without . Some affected individuals have brain abnormalities, such as absent or underdeveloped tissue connecting the left and right halves of the brain (agenesis or dysgenesis of ). However, intelligence is usually unaffected in people with this condition. Females with craniofrontonasal syndrome typically have more severe signs and symptoms than affected males, who often have hypertelorism and rarely, cleft lip.
Other common features of craniofrontonasal syndrome include extra folds of skin on the neck (), ridged nails, unusual curving of the fingers or toes (), extra fingers () or fingers that are fused together (), low-set breasts, a sunken chest (pectus excavatum), a spine that curves to the side (), or narrow and sloped shoulders with reduced range of motion. People with this condition may also have eyebrows that grow together in the middle (), with a low hairline in the back, or wiry hair.