Pierre Robin Sequence Foundation

PIERRE ROBIN SEQUENCE / SYNDROME (PRS)
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.

HOW COMMON IS THIS CONDITION?
PRS is rather uncommon. Frequency estimates range 12.4 per 100 000 live births (German case study), based on how strictly the condition is defined. In contrast, cleft lip and/or palate occurs once in every 700 live births.

WHAT CAUSES THIS CONDITION?
The basic cause appears to be the failure of the lower jaw to develop normally before birth. At about 7-10 weeks into a pregnancy, the lower jaw grows rapidly, allowing the tongue to descend from between the two halves of the palate. If, for some reason, the lower jaw does not grow properly, the tongue can prevent the palate from closing, resulting in a cleft palate. The small or displaced lower jaw also causes the tongue to be positioned at the back of the mouth, possibly causing breathing difficulty at birth. This “sequencing” of events is the reason why the condition has been classified as a deformation sequence. For some patients, these physical characteristics may result from another syndrome or chromosomal condition. The most common is Stickler Syndrome.

SYMPTOMS
Cleft soft palate
High-arched palate
Jaw that is very small with small (receding) chin
Jaw that is far back in the throat
Repeated ear infections
Small opening in the roof of the mouth
Tongue that is large compared to the jaw