What is Pierre Robin Syndrome?

Pierre Robin sequence or syndrome is an abnormality that affects the face and head.

Despite newborn screening tests, not all abnormalities can be avoided. One such abnormality that affects at least one in 14,000 individuals is known as Pierre Robin syndrome. However, this condition can be treated. Learn more about what causes this abnormality, how it is treated and diagnosed.

 

What Is Pierre Robin Syndrome?

Pierre Robin sequence or syndrome is an abnormality that affects the face and head. It is characterized by a small lower jaw (micrognathia), an obstruction of the airway, and a tongue that’s abnormally positioned (glossoptosis). Some babies born with this abnormality also manifest a cleft palate, which is an opening in the mouth’s roof. This is due to glossoptosis and micrognathia that affect palate formation and development prior to birth.

The features that affect individuals with Pierre Robin sequence can cause further health problems, such as difficulty eating and breathing. Babies affected may fail to grow and gain weight normally.

In other cases, the Pierre Robin sequence is part of another syndrome affecting other tissues and organs. This may be campomelic dysplasia or Stickler syndrome. For instances such as these, they are called syndromic. However, if the Pierre Robin sequence occurs on its own, it is called nonsyndromic. Around 40 percent of cases that are affected by this condition is nonsyndromic.

 

Causes

The most common cause of this abnormality is linked to genetic defects. This is particularly in genetic changes in the SOX9 gene which is in charge of providing instructions when it comes to the production of protein. This, in turn, plays an important part in the formation of organs and tissues during development of the embryo.

Moreover, the SOX9 protein helps regulate gene activity, specifically the genes that develop the mandible and the skeleton as a whole. Changes that occur in the SOX9 gene is linked with nonsyndromic cases of Pierre Robin sequence.

Non-genetic factors are speculated as causes for this abnormality such as the condition of the mother during pregnancy. Other causes have also been linked to this sequence which includes the following:

  • Oligohydramnios: low volume of the amniotic fluid
  • Myotonia: the weakness of the facial muscles
  • Disease of the Connective Tissues

 

Symptoms

Pierre Robin sequence may manifest symptoms that vary from one individual to the next. The Human Phenotype Ontology (HPO) collects information regarding symptoms related to this abnormality.

  • Abnormality of the Pharynx
  • Cleft Palate
  • Glossoptosis
  • Micrognathia
  • Obstruction of the Upper Airway
  • Respiratory Distress, Specifically in Infants

Due to the abnormalities in the oral cavity, there can be more severe issues problems as choking and less gain weight than what is expected. Also, children who have this abnormality are more at risk of getting acid reflux.

Other manifestations of this abnormality include lung and cardiovascular conditions like pulmonary hypertension and heart murmurs. There is also a reduction in the opening located between the right ventricle of the heart and the lung artery. This is called pulmonary stenosis.

Common anomalies that also manifest in individuals with this condition affect the musculoskeletal system. This includes anomalies in the vertebral column, feet, legs, and arm. Teeth defects are also noted along with an inflamed middle ear, also known as otitis media.

 

Diagnosis

For patients suspected to have this abnormality, a complete assessment of the airway is done. For an anomaly of the larynx and trachea, a tracheostomy is also required. Once it has been diagnosed, doctors do a polysomnogram, which is a sleep study. This determines the degree of obstruction in the airways.

 

Treatment

For each patient, the treatment varies and is focused on their needs. Modifications to feeding and breathing are done to prevent the risk of choking. This involves surgery. For surgery, this includes the following:

  1. Tongue-Lip Adhesion

In this procedure, the underside of the tongue’s tip is sutured to the lower lip. This helps the tongue move forward and stay in this position. If the procedure proves successful, then the sutures are removed in six months.

  1. Distraction Osteogenesis

A device, external or internal, is placed on the mandible. A posterior cut is made. With the help of the device, the jaw moves forward and moves the tongue along as well. This helps remove the obstruction in the airway.

For mild cases of this sequence, treatment is focused on the proper positioning of the child. A child is positioned face-down or on the side to let the tongue move away from the back of the throat.

 

Related Disorders

Symptoms that manifest in individuals with this abnormality is similar to other disorders. Some of these disorders include the following:

  1. Stickler Syndrome

This is a connective tissue disorder that is quite rare. It affects the joints, skeleton, ears, and eyes. Some of its symptoms include a detached retina, hearing loss, nearsightedness, and joint pain. Individuals with this disorder may also manifest micrognathia, cleft palate, and glossoptosis.

  1. Chromosome 22q11.2 Deletion Syndrome

It is also known as a velocardiofacial syndrome. This disorder is because of a tiny portion that is missing from chromosome 22. Moreover, this disorder is linked to numerous health problems, such as:

  • Congenital Heart Disease
  • Abnormalities of the Palate
  • Immune System Dysfunction
  • Hypocalcemia
  • Endocrine Abnormalities
  • Gastrointestinal Disorders
  • Hearing Loss
  • Seizures
  • Skeletal Abnormalities
  1. Treacher Collins Syndrome

This is another genetic disorder that is quite rare. It is quite notable because of the abnormality of the face and head. Unlike Pierre Robin sequence, micrognathia is more pronounced in Treacher Collins. There is also a malformation of the eyes and hearing loss.

Other disorders not detailed but similar to Pierre Robin include the following:

  • Chromosome 11
  • Campopeli Dysplasia
  • Cerebro-costo-mandibular Syndrome
  • Catel Manzke Syndrome
  • CHARGE Syndrome
  • Partial Trisomy 11q
  • Trisomy 18 Syndrome

The isolated or nonsyndromic cases of Pierre Robin syndrome is not a condition that’s lifelong. A child’s jaw may grow to its normal size. Some studies and research have shown that the jaws of those affected have indeed grown normally by the time school begins. For parents worried that this condition may affect their other future child, there is a 99 percent chance that it is unlikely to happen.

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