Axenfeld-Rieger Syndrome, Type 1

Alternative Names

  • Rieger Syndrome, Type 1
  • RIEG1
  • RIEG
  • RGS
  • Iridogoniodysgenesis with Somatic Anomalies
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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

Congenital malformations of eye, ear, face and neck

OMIM Number

180500

Mode of Inheritance

Autosomal dominant

Gene Map Locus

4q25

Description

Rieger Syndrome is a rare genetic disorder characterized by dental, ocular, and craniofacial abnormalities. Ocular abnormalities include glaucoma, posterior embryotoxon, prominent Schwalbe ring, iris hypoplasia, iridocorneal adhesion, and other corneal defects. Dental anomalies seen in this condition include hypodontia or partial adontia, with maxillary incisors and second premolars being the teeth most commonly missing, conical shaped teeth, delayed eruption, and shortened roots. Other features include broad flat nasal root, prognathism, short stature, myotonic dystrophy, brachydactyly, polydactyly, anal stenosis, and mental deficiency. It is believed that the condition results from a developmental arrest of specific anterior segment tissue originating from neural crest cells, sometime in the third trimester. Interestingly, most clinicians believe that anterior chamber cleavage syndromes, such as Axenfeld's anomaly, iridiogoniodysgenesis syndrome, Rieger anomaly, and Rieger syndrome, are all a continuum of a single developmental disorder.

Rieger syndrome needs very basic management. Contact lenses may be fitted in patients who require them. The most important complication to be aware of is the risk of developing secondary glaucoma. All patients therefore, need monitoring throughout their life.

Usually, Reiger syndrome is inherited in an autosomal dominant manner. However, autosomal recessive and/or sporadic transmission has also been noted. Recent research on the genetic basis of the condition has identified at least three different loci to be linked to it. The first of these, on chromosome 4q25, has been identified to harbor the PITX2 (Pituitary Homeobox 2) gene. This gene plays a critical role in the intermediate steps controlling left-right asymmetry in the eye and brain tissue, and it is clear to see how mutations in it could lead to phenotypic effects noted in Rieger Syndrome. The FKHL7 gene, located on chromosome 6p25 and a locus on 13q14 are other regions associated with Rieger syndrome.

Epidemiology in the Arab World

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Other Reports

Libya

Gaballah and Raghyan (2001) reported a typical example of Rieger syndrome in a 19-year old Libyan patient who presented with a requirement for replacing his missing lower front teeth. Upon examination, he was found to be below the accepted values for height and weight for his age, and had protruding periumbilical folds. He was also found to have features typical of Rieger syndrome with regards to ocular (small eyes, urkus juvenile, micro cornea, convergent squint, and myopic astigmatism), craniofacial (wide nasal bridge, maxillary and mandibular hypoplasia, and underdevelopment of anterior and posterior cranial bases), and dental (hypodontia, microdontia, retained primary teeth, shape variation, and an anterior open-bite) anomalies. He was managed with appropriate dental treatment and referred to ophthalmological care.

[Gaballah KY, Raghyan V. Rieger's Syndrome. Qatar Med J. 2001; 10(2):69-71.]

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