Richner-Hanhart Syndrome: What It Is and How It Is Treated

Written by Medicover Team and Medically Reviewed by Dr Mamta Vadhel , Ophthalmology

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1. Causes 2. Find a Doctor 3. Diagnosis 4. Treatment 5. FAQs

Richner-Hanhart syndrome is a rare inherited metabolic disorder that affects the body's ability to break down the amino acid tyrosine. It is also known as tyrosinemia type II or oculocutaneous tyrosinemia.

The condition is caused by a deficiency of the enzyme tyrosine aminotransferase, which leads to abnormally high levels of tyrosine in the blood and tissues. Richner-Hanhart syndrome mainly affects the eyes and skin and may also cause developmental or intellectual problems in some individuals.

What Are the Symptoms of Richner-Hanhart Syndrome?

Symptoms of Richner-Hanhart syndrome most commonly affect the eyes and skin. Signs may begin during infancy or childhood, although the age of onset and severity can vary.

Eye Symptoms

Eye Pain: Severe pain may occur because of inflammation and damage to the cornea.
Eye Redness: The eyes may appear persistently red and irritated.
Sensitivity to Light: Abnormal sensitivity to bright light, known as photophobia, is common.
Excessive Tearing: The eyes may produce more tears than usual.
Corneal Lesions: Painful corneal inflammation, erosions or ulcers can develop.
Vision Problems: Untreated corneal damage may interfere with vision.

Skin Symptoms

Palmoplantar Hyperkeratosis: Thickened areas of skin can develop on the palms of the hands and soles of the feet.
Painful Skin Lesions: Thickened plaques may become painful, especially on pressure-bearing areas.
Cracking of the Skin: Severe thickening may lead to painful cracks or fissures.
Walking Difficulties: Painful lesions on the soles may make standing and walking uncomfortable.

Developmental and Neurological Symptoms

Intellectual Disability: Some affected individuals may have intellectual impairment.
Developmental Delay: Developmental milestones may be delayed in some children.
Learning Difficulties: Problems with learning or cognitive development may occur.

What Causes Richner-Hanhart Syndrome?

Richner-Hanhart syndrome is caused by genetic changes that affect the body's ability to break down tyrosine. Tyrosine is an amino acid obtained from protein-containing foods and produced during the breakdown of another amino acid called phenylalanine.

TAT Gene Mutations: Disease-causing changes in the TAT gene are responsible for Richner-Hanhart syndrome.
Tyrosine Aminotransferase Deficiency: TAT gene mutations reduce or prevent the activity of the enzyme tyrosine aminotransferase.
Tyrosine Accumulation: Without enough functional enzyme, tyrosine builds up in the blood and tissues.
Tissue Damage: High tyrosine levels can damage the cornea and contribute to painful skin lesions.

How Is Richner-Hanhart Syndrome Inherited?

Richner-Hanhart syndrome follows an autosomal recessive inheritance pattern. An affected individual usually inherits one altered copy of the TAT gene from each parent.

Parents who carry one altered gene copy usually do not have symptoms.
When both parents are carriers, each pregnancy has a risk of producing an affected child.
Genetic counselling can help families understand inheritance and recurrence risks.

When to See a Doctor for Richner-Hanhart Syndrome?

Medical evaluation by a Metabolic Specialist or Ophthalmologist is recommended when a child develops unexplained painful eye redness, severe light sensitivity, excessive tearing, corneal problems, or thickened skin on the palms and soles. Early diagnosis and dietary treatment can help prevent complications.

You should see a doctor if you have:

Persistent eye pain, redness or sensitivity to light
Painful thickened skin on the palms or soles
Developmental or learning difficulties with eye or skin symptoms

Get medical help immediately if:

Severe eye pain or sudden vision changes develop
A child cannot open the eyes because of pain or light sensitivity
Corneal ulcers or severe eye inflammation are suspected

These could be signs of a serious complication like corneal damage, which needs urgent care.

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How Is Richner-Hanhart Syndrome Diagnosed?

Diagnosis is based on characteristic eye and skin symptoms, elevated tyrosine levels and genetic or enzyme testing. Early diagnosis is important because appropriate dietary treatment can reduce tyrosine levels and improve symptoms.

Blood Tests

Blood tests can detect abnormally high levels of tyrosine. Elevated blood tyrosine in a person with characteristic eye or skin findings can strongly suggest tyrosinemia type II.

Urine Tests

Urine testing may identify increased levels of tyrosine and related metabolites produced when tyrosine metabolism is disrupted.

Eye Examination

An ophthalmologist can examine the cornea for inflammation, erosions, ulcers and other abnormalities associated with high tyrosine levels.

Skin Examination

A dermatologist may assess thickened, painful or cracked skin lesions on the palms and soles.

Genetic Testing

Molecular genetic testing can identify disease-causing changes in the TAT gene and help confirm the diagnosis.

Newborn Screening

In some settings, elevated tyrosine may be detected through newborn screening. However, additional testing is required because high tyrosine levels can occur for several reasons.

How Is Richner-Hanhart Syndrome Treated?

Treatment focuses on reducing tyrosine levels in the body. Early and consistent treatment can improve eye and skin symptoms and may help reduce the risk of long-term complications.

Low-Tyrosine and Low-Phenylalanine Diet

A specialised diet restricting tyrosine and phenylalanine is the main treatment.
Protein intake must be carefully managed under medical supervision.
Special medical formulas may be recommended to provide adequate nutrition while limiting these amino acids.

Regular Nutritional Monitoring

Blood tyrosine levels should be checked regularly.
Growth and nutritional status should be monitored, especially in children.
A metabolic dietitian can adjust the diet according to age, growth and blood test results.

Ophthalmologic Care

Regular eye examinations can help monitor corneal damage.
Eye treatments may be used to relieve symptoms and protect the cornea while tyrosine levels are brought under control.
Severe eye pain or corneal ulcers require prompt specialist care.

Skin Care

Skin specialists may recommend treatments to soften thickened skin and reduce discomfort.
Protecting pressure-bearing areas of the hands and feet may help reduce pain.
Skin lesions often improve when blood tyrosine levels are effectively controlled.

Developmental Support

Children with developmental or learning difficulties may benefit from early intervention.
Speech, occupational or educational support can be provided according to individual needs.

Genetic Counselling

Genetic counselling can help families understand the autosomal recessive inheritance pattern.
Carrier testing and reproductive options may be discussed when appropriate.

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What Are the Risk Factors for Richner-Hanhart Syndrome?

Richner-Hanhart syndrome is a genetic disorder, so its main risk factors relate to inheritance rather than lifestyle or environmental exposure.

Carrier Parents: The risk is increased when both parents carry a disease-causing change in the TAT gene.
Family History: Having an affected family member may increase the likelihood of carrying the altered gene.
Consanguinity: Biological relationship between parents can increase the chance that both carry the same rare recessive genetic change.

What Are the Complications of Richner-Hanhart Syndrome?

Without appropriate treatment, persistently high tyrosine levels can cause ongoing damage to the eyes and skin and may contribute to developmental problems.

Severe corneal inflammation
Corneal ulcers and scarring
Vision impairment
Painful palm and sole lesions
Difficulty walking because of foot pain
Developmental or learning difficulties

Can Richner-Hanhart Syndrome Be Prevented?

Richner-Hanhart syndrome cannot be prevented because it is an inherited genetic disorder. However, early diagnosis and lifelong management of tyrosine levels can help prevent or reduce many complications.