It is usually a congenital developmental feature that results from the failure of the palatal shelves to fuse correctly in development, the same phenomenon that leads to cleft palate.
[1] 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 high-arched palate may result in a narrowed airway and sleep disordered breathing.
[2] Examples of conditions which may be associated with a high-arched palate include: