Pierre Robin Sequence

What is Pierre Robin sequence?

Pierre Robin sequence is a condition present at the time of birth that affects the infant’s mouth and jaw structure. The baby has an abnormally small lower jaw (micrognathia), a tongue placed further back in the mouth (glossoptosis), and an opening in the roof of the mouth (cleft palate). This combination can lead to breathing and eating problems in early life. The condition is called a sequence because one of its features, underdevelopment of the lower jaw, sets off a sequence of events before birth that cause the other symptoms. Pierre Robin sequence can occur on its own (isolated Pierre Robin sequence) or it can be associated with a variety of other signs and symptoms, which would classify it as syndromic. Isolated Pierre Robin sequence affects about 1 in 8,500 to 14,000 people. It affects males and females equally.

What are the symptoms of Pierre Robin sequence?

The symptoms of Pierre Robin sequence include the following:

• Trouble breathing
• Respiratory distress
• Feeding problems in early life
• Failure to grow and gain weight at a normal rate
• Repeated ear infections
• Sleep disorders, such as obstructive sleep apnea
• Benign heart murmur
• Pulmonary hypertension (high blood pressure in the arteries of the lungs)
• Pulmonary stenosis (Narrowing of the opening between the lung artery and heart’s right ventricle)
• Anomalies in the musculoskeletal system
• Eye defects

What causes Pierre Robin sequence?

The exact cause of Pierre Robin sequence is unknown. However, studies show that a genetic cause of some cases is the change in DNA near the SOX9 gene. It is likely that changes in other genes are also involved, but they have yet to be identified. The SOX9 gene contains instructions for making a protein called protein SOX9, which plays an important role in forming many tissues and organs during embryonic development. The protein also regulates the activity of other genes that are important for developing the skeleton, including the jaw. The genetic changes near the SOX9 gene involved with Pierre Robin sequence are thought to disrupt regions of DNA called enhancers, which normally regulate the activity of the SOX9 gene. These alterations lower the gene’s activity, which means protein SOX9 can’t control the genes essential for normal development of the lower jaw. This leads to the micrognathia, or the very small lower jaw, that then leads to the other symptoms of the condition. Some doctors believe that nongenetic factors, such as conditions during pregnancy that restrict growth of the jaw, might cause some cases.

How is Pierre Robin sequence diagnosed?

Pierre Robin sequence can be diagnosed using the following procedures:

• Before birth, using ultrasounds
• Physical examimations
• Close observation of breathing

What are the treatments for Pierre Robin sequence?

Pierre Robin sequence treatment includes, but is not limited to:

• Intubation to assist with breathing
• Surgery to assist with breathing
• Feeding modifications to prevent choking
• Surgery to close the palate
• Speech therapy
• Genetic counseling

Where can I find out more about Pierre Robin sequence?

• National Organization for Rare Disorders (NORD)
• NIH
• Genetics and Rare Diseases Information Center
• Medline Plus