Pierre Robin Sequence or Complex (pronounced “Roban”) is the name given to a birth condition that involves the lower jaw being either small in size (micrognathia) or set back from the upper jaw (retrognathia). As a result, the tongue tends to be displaced back towards the throat, where it can fall back and obstruct the airway (glossoptosis). Most infants, but not all, will also have a cleft palate, but none will have a cleft lip.
Over the years there have been several names given to the condition, including Pierre Robin Syndrome, Pierre Robin Triad, and Robin Anomalad. Based on the varying features and causes of the condition, either “Robin Sequence” or “Robin Complex” may be an appropriate description for a specific patient. Pierre Robin was a French physician who first reported the combination of small lower jaw, cleft palate, and tongue displacement in 1923.
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, however.
How common is this condition?
Robin Sequence/Complex is rather uncommon. Frequency estimates range from 1 in 2,000 to 30,000 births, based on how strictly the condition is defined. In contrast, cleft lip and/or palate occurs once in every 700 live births.
The exact causes of Pierre Robin sequence are unknown. It may be part of many genetic syndromes.
The lower jaw develops slowly before birth, but may grow faster during the first few years of life.
Symptoms of this condition include:
- Cleft soft palate
- High-arched palate
- Jaw that is very small with a small chin
- Jaw that is far back in the throat
- Repeated ear infections
- Small opening in the roof of the mouth, which may cause choking or liquids coming back out through the nose
- Teeth that appear when the baby is born
- Tongue that is large compared to the jaw