A<unk>  (also termed<unk> -vaulted<unk>  is where the<unk>  is unusually<unk>  and narrow. It is usually a congenital developmental feature that results from the failure of the<unk> l shelves to fuse correctly in development, the same phenomenon that leads to cleft<unk> . It may occur in isolation or in association with a number of conditions. It may also be an acquired condition caused by chronic thumb-sucking. A<unk>  may result in a narrowed airway and sleep disordered breathing. Examples of conditions which may be associated with a<unk>  include: * Allergic rhinitis * Apert syndrome * Crouzon syndrome * Down syndrome * Ehlers-Danlos Syndrome * Fragile X syndrome * Incontinentia pigmenti * Marfan syndrome * Treacher Collins syndrome * Upper Airway Resistance Syndrome
High-arched palate
Hemifacial microsomia
Hypodontia
Maxillary hypoplasia
Low-set ears
Anodontia
Shovel-shaped incisors
Webbed neck