Pierre Robin Syndrome (PRS)

Synonyms

Pierre Robin malformation
Pierre Robin sequence
Pierre Robin anomaly
Pierre Robin anomalad
Syndrome de Pierre Robin (French)

Medical history

Pierre Robin (1867–1950) was a French stomatologist (dentist). He was professor at the School of Stomatology in France. From 1914, he was editor-in-chief of the Revue de Stomatologie. According to some reports Robin died in 1947. 

The PRS was described by Pierre Robin in 1923. PRS is named after him.

Introduction

PRS is a congenital condition of facial abnormalities in humans. PRS is a sequence, i.e. a chain of certain developmental malformations, one entailing the next. The three salient features are, an incomplete roof of the mouth (cleft palate), micrognathia (a small jaw) and glossoptosis (obstruction of the trachea, caused by backwards displacement of the tongue base). 

Epidemiology

PRS has an incidence ranging from 1 in 8500 to 1 in 14,000.

Clinical definition

PRS is a particular disease that combines three facial abnormalities that are the consequence of each other:

1. posterior median cleft palate,
2. a retrognathia (chin back)
3. glossoptosis (tendency of the tongue to fall backward into the throat).
4. Infants have feeding difficulties, respiratory, or cardiac function 
5. The PRS may be associated with other syndromes, it is called PRS associated.

Signs and symptoms

PRS is characterized by:

1. an unusually small mandible (micrognathia), 
2. posterior displacement or retraction of the tongue (glossoptosis  or vertical tongue), and 
3. upper obstruction of trachea (airway obstruction). 
4. Incomplete closure of the roof of the mouth (cleft palate) is present in the majority of patients, and is commonly U-shaped.

Causes and associated conditions

PRS may occur in isolation, but it is often part of an underlying disorder. The most common is Stickler Syndrome. Others causing PRS, according to Dr. Robert J. Sphrintzen Ph.D. of the Center for Craniofacial Disorders Montefiore Medical Center, are Velocardiofacial syndrome, Fetal Alcohol Syndrome and Treacher Collins Syndrome. For more disorders associated with PRS, see Dr. Sphrintzen's article entitled The Implications of the Diagnosis of Robin Sequence.

Research disciplines involved

Cellular biology, molecular biology, embryology, developmental biology, genetics, clinical outcomes, and epidemiology.

Genetic research and genetic causes of PRS

Refer to publication by Prof. Véronique Abadie in Nature Genetics.
http://www.nature.com/ng/journal/v41/n3/abs/ng.329.html

1. PRS is isolated sporadically in most cases. However, about 10-15% of cases are familial and autosomal dominant transmission.
2. A genetic cause to PRS was recently identified. PRS may be caused by genetic anomalies at chromosomes 2, 11, or 17.

Research was focused on mutations of the non-coding sequences, which is at a considerable distance from a gene involved in the developmental anomaly.

Gene locus 17q24 and SOX9 gene

Researchers from Inserm U781 - University Paris Descartes, Necker to E.M. Hospital have demonstrated for the first time the role of highly conserved between species and very far from a developmental gene, SOX9 noncoding sequences that they control developmental anomaly. 

After mapping this gene locus in a vast desert (2.5 megabases) on chromosome 17q24, their study focused on the SOX9 gene. It is a good candidate to explain this rare disease because it is the only gene present within this region and is particularly involved in the development of the jaw. However, it was found that its sequence is not altered in people with this syndrome, which is why researchers are interested in the non-coding elements present upstream and downstream of this gene.

The SOX9 gene has been implicated. Researchers have demonstrated the existence of genomic alterations leading to abnormal expression of this gene at the specific craniofacial tissue. This discovery was published in Nature Genetics.

No gene is known for isolated Pierre Robin. In syndromic forms, the situation is variable depending on the case.

This is one of the first examples of non-coding regulatory mutation of highly conserved sequences in the human genome, located at great distance from the gene on which they act.

Diagnosis

The syndrome is generally diagnosed clinically shortly after birth. The infant usually has respiratory difficulty, especially when supine. The cleft palate is often U-shaped and wider than in cleft palate that is not associated with this syndrome.

Prognosis

Hospital USM (HUSM) experiences with PRS:

1. One baby survived to age 1 year in ICU, and then died. She's the 8th out of 9 siblings. She had cleft palate or "sumbing dalam mulut".
2. Another patient is now 9 years old. However, mental capacity deteriorated and has forced the child to quit school.

Medical monitoring

The level of monitoring required will depend on medical severity and at the paramedical level:

1. Pediatric
2. ENT 
3. Speech therapy
4. Ophthalmology (the retina folds over itself  - leading to blindness)
5. Maxillofacial and orthodontic (some are born with teeth on a small gum)
6. Physiotherapy
7. Psychomotor
8. Cognitive
9. Genetic counseling.

The nature of monitoring makes it necessary to have a multidisciplinary team that is better able to deal with the diversity of challenges. This team is also accustomed to dealing with PRS.

External links and networks

Wikipedia - Pierre Robin syndrome
http://en.wikipedia.org/wiki/Pierre_Robin_syndrome

Pierre Robin Network based in Illinois, USA

http://www.pierrerobin.org/

Springboard Pierre Robin syndrome based in Paris, France (French)

http://www.tremplin-spr.org/

Necker Hospital for Sick Children in Paris

Center for Rare Diseases

Seattle Children's Hospital

https://www.facebook.com/seattlechildrens

Pierre Robin in Seattle Children's Hospital

http://www.seattlechildrens.org/medical-conditions/chromosomal-genetic-conditions/pierre/#

Genetics research in France

http://www.tremplin-spr.org/genetique.php