Axenfeld-Rieger syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Axenfeld-Rieger syndrome is primarily an eye disorder, although it can also affect other parts of the body. This condition is characterized by abnormalities of the front part of the eye, an area known as the anterior segment. For example, the colored part of the eye (the iris), may be thin or poorly developed. The iris normally has a single central hole, called the pupil, through which light enters the eye. People with Axenfeld-Rieger syndrome often have a pupil that is off-center (corectopia) or extra holes in the iris that can look like multiple pupils (polycoria). This condition can also cause abnormalities of the cornea, which is the clear front covering of the eye.

About half of affected individuals develop glaucoma, a serious condition that increases pressure inside the eye. When glaucoma occurs with Axenfeld-Rieger syndrome, it most often develops in late childhood or adolescence, although it can occur as early as infancy. Glaucoma can cause vision loss or blindness.

The signs and symptoms of Axenfeld-Rieger syndrome can also affect other parts of the body. Many affected individuals have distinctive facial features such as widely spaced eyes (hypertelorism); a flattened mid-face with a broad, flat nasal bridge; and a prominent forehead. The condition is also associated with dental abnormalities including unusually small teeth (microdontia) or fewer than normal teeth (oligodontia). Some people with Axenfeld-Rieger syndrome have extra folds of skin around their belly button (redundant periumbilical skin). Other, less common features can include heart defects, the opening of the urethra on the underside of the penis (hypospadias), narrowing of the anus (anal stenosis), and abnormalities of the pituitary gland that can result in slow growth.

Researchers have described at least three types of Axenfeld-Rieger syndrome. The types, which are numbered 1 through 3, are distinguished by their genetic cause.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Axenfeld-Rieger syndrome results from mutations in at least two known genes, PITX2 and FOXC1. PITX2 gene mutations cause type 1, and FOXC1 gene mutations cause type 3. The gene associated with type 2 is likely located on chromosome 13, but it has not been identified. The proteins produced from the PITX2 and FOXC1 genes are transcription factors, which means they attach (bind) to DNA and help control the activity of other genes. These transcription factors are active before birth in the developing eye and in other parts of the body. They appear to play important roles in embryonic development, particularly in the formation of structures in the anterior segment of the eye.

Mutations in either the PITX2 or FOXC1 gene disrupt the activity of other genes that are needed for normal development. Impaired regulation of these genes leads to problems in the formation of the anterior segment of the eye and other parts of the body. These developmental abnormalities underlie the characteristic features of Axenfeld-Rieger syndrome. Affected individuals with PITX2 gene mutations are more likely than those with FOXC1 gene mutations to have abnormalities affecting parts of the body other than the eye.

Some people with Axenfeld-Rieger syndrome do not have identified mutations in the PITX2 or FOXC1 genes. In these individuals, the cause of the condition is unknown. Other as-yet-unidentified genes may also cause Axenfeld-Rieger syndrome.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Axenfeld-Rieger syndrome has an estimated prevalence of 1 in 200,000 people.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormal anterior chamber morphology · Very frequent (99-80%)

Abnormality of the anterior chamber, which is the space in the eye that is behind the cornea and in front of the iris.

Aplasia/Hypoplasia of the iris · Very frequent (99-80%)

Absence or underdevelopment of the iris.

Posterior embryotoxon · Very frequent (99-80%)

A posterior embryotoxon is the presence of a prominent and anteriorly displaced line of Schwalbe.

Abnormal cardiovascular system morphology · Frequent (79-30%)

Any structural anomaly of the heart and blood vessels.

Everted lower lip vermilion · Frequent (79-30%)

An abnormal configuration of the lower lip such that it is turned outward i.e., everted, with the Inner aspect of the lower lip vermilion (normally opposing the teeth) being visible in a frontal view.

Glaucoma · Frequent (79-30%)

Glaucoma refers loss of retinal ganglion cells in a characteristic pattern of optic neuropathy usually associated with increased intraocular pressure.

Hearing impairment · Frequent (79-30%)

A decreased magnitude of the sensory perception of sound.

Midface retrusion · Frequent (79-30%)

Posterior positions and/or vertical shortening of the infraorbital and perialar regions, or increased concavity of the face and/or reduced nasolabial angle.

Other findings in the same source

From: Orphanet

Additional reported features include Abnormality of the hypothalamus-pituitary axis (Occasional (29-5%)); Anal stenosis (Occasional (29-5%)); Depressed nasal bridge (Occasional (29-5%)); Growth delay (Occasional (29-5%)); Hypertelorism (Occasional (29-5%)); Hypodontia (Occasional (29-5%)); Hypoplasia of the maxilla (Occasional (29-5%)); Hypospadias (Occasional (29-5%)); Microdontia (Occasional (29-5%)); Prominent forehead (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Axenfeld-Rieger syndrome is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Axenfeld-Rieger syndrome. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.