Pierre Robin (pronounced “Roban”) Sequence or Syndrome (PRS) is a condition present at birth, in which the infant has a smaller-than-normal lower jaw (micrognathia) or set back from the upper jaw (retrognathia), a tongue that falls back in the throat and obstructs the airway (glossoptosis), and difficulty breathing. Most infants, but not all, will also have incomplete closure of the roof of the mouth (cleft palate), and is commonly U-shaped.