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Axenfeld-Rieger syndrome
This rare inherited disorder can lead to issues with vision due to glaucoma and may involve unique facial and dental features. It primarily affects eye development during pregnancy and often has an autosomal dominant inheritance pattern.
Overview
Axenfeld-Rieger syndrome (ARS) is a rare genetic disorder that primarily affects the development of the front part of the eye, known as the anterior segment. Individuals with ARS often have distinctive eye features, but the condition can also affect other parts of the body, such as the teeth, skeleton, and umbilical area [PMID:33671239]. The severity of these features can vary significantly among affected individuals, even within the same family [PMID:19363073].
Problems in the anterior segment of the eye can increase the risk of developing glaucoma, a condition characterised by increased pressure inside the eye that can damage the optic nerve and lead to vision loss if not managed. ARS is generally considered a developmental disorder, meaning the affected body parts did not form correctly during foetal development.
While ARS is a rare condition, it is important for affected individuals to receive comprehensive medical care to monitor for potential complications, particularly those affecting vision. Early diagnosis and ongoing management can help to preserve vision and address other associated health concerns.
Symptoms & clinical features
The symptoms of Axenfeld-Rieger syndrome vary, but key features often involve the eyes. These can include an unusually prominent white ring at the edge of the iris (posterior embryotoxon), a displaced pupil (corectopia), or multiple pupils (polycoria) [PMID:19363073]. The iris itself, the coloured part of the eye, can appear underdeveloped, with strands of tissue stretching across the pupil.
Beyond the eye, individuals with ARS may have distinct facial features, such as a prominent forehead, widely spaced eyes (hypertelorism), and a flattened mid-face. Dental anomalies are common and can include smaller-than-average teeth (microdontia) or fewer teeth than usual (oligodontia or hypodontia). Some individuals may also have an umbilical hernia or excess skin around the navel [PMID:33671239]. Skeletal abnormalities, particularly affecting the hands or feet, are less common but have been reported.
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Affected organs
Axenfeld-Rieger syndrome primarily impacts the eyes, specifically the anterior segment. This includes structures like the iris, cornea, and drainage angle of the eye. Disruptions in the development of these structures significantly increase the risk of glaucoma, which can lead to damage of the optic nerve and permanent vision loss if untreated.
Other affected body systems can include the dental system, leading to abnormalities in tooth number, size, and shape. The musculoskeletal system may show minor hand or foot differences, though these are less frequent. The umbilical region can also be affected, with some individuals presenting with an umbilical hernia or redundant periumbilical skin.
Risks & severity
The severity of Axenfeld-Rieger syndrome is highly variable, ranging from mild ocular features to more widespread developmental issues. The most significant and common complication is the development of glaucoma, which affects approximately 50% of individuals with ARS. Glaucoma typically develops in childhood or early adulthood, and its timely detection and management are crucial for preserving vision.
While the primary risks are ocular and relate to potential vision loss from glaucoma, other features like dental anomalies or umbilical variations are generally not life-threatening but can influence quality of life. The condition is rare, and its exact prevalence is not well established. The genetic changes associated with ARS are typically present from birth, leading to developmental issues manifesting at various stages.
Genetic causes
Axenfeld-Rieger syndrome is primarily caused by pathogenic variants, also known as mutations, in either the FOXC1 or PITX2 genes. These genes provide instructions for making proteins that act as transcription factors. Transcription factors are crucial for controlling the activity of other genes, playing a vital role in foetal development.
FOXC1 (forkhead box C1) and PITX2 (paired like homeodomain 2) are particularly important for the normal development of ocular structures, especially the anterior segment of the eye, and other tissues like teeth and the umbilical area. When a pathogenic variant occurs in one of these genes, the protein produced may not function correctly or may be produced in insufficient amounts. This disruption to normal gene regulation during development leads to the characteristic features of ARS.
Around 40-50% of individuals diagnosed with ARS have an identifiable pathogenic variant in either FOXC1 or PITX2. In some cases, no genetic cause is identified, suggesting other genes may also be involved, or current genetic testing methods may not detect all possible variants.
- FOXC1 forkhead box C1
- PITX2 paired like homeodomain 2
Inheritance pattern
Axenfeld-Rieger syndrome is inherited in an autosomal dominant pattern. This means that only one copy of the altered gene in each cell is sufficient to cause the condition. An affected individual has a 50% chance of passing on the pathogenic variant, and therefore the condition, to each of their children, regardless of the child's sex.
In many cases, an individual with ARS inherits the pathogenic variant from an affected parent. However, some cases arise from a new, or de novo, pathogenic variant in the gene, where there is no family history of the condition. In such instances, the variant occurs for the first time in that individual. Even if a variant occurs de novo, the affected individual then has a 50% chance of passing it to their offspring.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
Diagnosis & testing
Diagnosing Axenfeld-Rieger syndrome typically involves a comprehensive eye examination by an ophthalmologist, who can identify the characteristic anterior segment abnormalities. Other clinical features such as dental anomalies or umbilical changes may also contribute to the diagnosis. If ARS is suspected, a referral to a clinical genetics service is typical.
Confirmation of the diagnosis is usually achieved through genetic testing. This testing looks for pathogenic variants in the FOXC1 and PITX2 genes. Genetic testing for ARS is available within the NHS Genomic Medicine Service (GMS) pathways. Relevant R-codes for genetic testing for inherited eye disorders, which would include ARS, can be found on the NHS England National Genomic Test Directory. A genetic counsellor can explain the testing process, interpretation of results, and implications for family members.
Management & lifestyle
Management for individuals with Axenfeld-Rieger syndrome focuses on monitoring and treating the associated symptoms, particularly glaucoma. Regular eye examinations are essential to detect and manage glaucoma early, often starting in childhood. Treatment for glaucoma may involve eye drops to reduce intraocular pressure, laser therapy, or surgery.
Other clinical features like dental anomalies can be managed by a dentist or orthodontist. If an umbilical hernia is present and causes problems, it may require surgical intervention. Individuals with ARS are typically managed by a multidisciplinary team, potentially including ophthalmologists, geneticists, paediatricians, and dentists. Genetic counselling is an important part of the care pathway to provide information about the condition, its inheritance pattern, and implications for family planning.
UK care pathway
In the UK, individuals suspected of having Axenfeld-Rieger syndrome are typically referred to clinical genetics services for assessment and genetic testing. This testing is often performed through the NHS Genomic Medicine Service (GMS) pathways, following the National Genomic Test Directory. Genetic counsellors play a crucial role in providing support and information regarding the genetic diagnosis, inheritance, and family implications. Referrals for specialist ophthalmology care for management of glaucoma and other eye features are a key part of the care pathway.
Frequently asked questions
What is the main concern with Axenfeld-Rieger syndrome?
The most significant concern with Axenfeld-Rieger syndrome is the increased risk of developing glaucoma, a condition that can damage the optic nerve and lead to vision loss if not effectively managed. Regular eye check-ups are vital for early detection.
Can Axenfeld-Rieger syndrome be passed down to children?
Yes, Axenfeld-Rieger syndrome is inherited in an autosomal dominant pattern. This means an affected individual has a 50% chance of passing the condition to each of their children. Genetic counselling can provide more personalised information.
Are the dental problems in Axenfeld-Rieger syndrome serious?
Dental problems, such as missing or smaller teeth, are common in ARS, but they are generally not life-threatening. They can be managed by a dentist or orthodontist to address cosmetic or functional concerns.
How is Axenfeld-Rieger syndrome diagnosed?
Diagnosis typically involves an eye examination to identify characteristic features, followed by genetic testing to look for pathogenic changes in the FOXC1 or PITX2 genes. A referral to a clinical genetics service is common in the UK.
Is there a cure for Axenfeld-Rieger syndrome?
Currently, there is no cure for Axenfeld-Rieger syndrome itself, as it is a developmental condition. However, the associated symptoms, particularly glaucoma, can be managed effectively through ophthalmological treatment to preserve vision.
References
- Seifi M, Walter MA. Axenfeld-Rieger syndrome. Clinical genetics. 2018. PMID: 28972279
- Reis LM, Maheshwari M, Capasso J. Axenfeld-Rieger syndrome: more than meets the eye. Journal of medical genetics. 2023. PMID: 35882526
- Tripathy K, Salini B. Axenfeld-Rieger Syndrome. 2026. PMID: 30860739
- Moshirfar M, Hastings J, Ronquillo Y. Megalocornea. 2026. PMID: 32119261
- Higgins RC, Bingcang CM, Dowdall JR. Axenfeld-Rieger Syndrome and Possible Airway Complications. Ear, nose, & throat journal. 2024. PMID: 38321760
- Rao A, Padhy D, Sarangi S. Unclassified Axenfeld-Rieger Syndrome: A CASE SERIES and Review of Literature. Seminars in ophthalmology. 2018. PMID: 27929720
- Valikodath N, Johns JA, Godown J. Cardiac anomalies in Axenfeld-Rieger syndrome. Cardiology in the young. 2023. PMID: 36543336
- Arte S, Pöyhönen M, Myllymäki E. Craniofacial and dental features of Axenfeld-Rieger syndrome patients with PITX2 mutations. Orthodontics & craniofacial research. 2023. PMID: 36620911