Richner Hanhart syndrome

=Richner-Hanhart Syndrome = Richner-Hanhart Syndrome, also known as Tyrosinemia Type II, is a rare autosomal recessive metabolic disorder characterized by elevated levels of the amino acid tyrosine in the blood. This condition is caused by a deficiency of the enzyme tyrosine aminotransferase, which is crucial for the normal catabolism of tyrosine.

Clinical Features

Individuals with Richner-Hanhart Syndrome typically present with a triad of symptoms:

• Ocular manifestations: Patients often develop painful corneal ulcers, photophobia, and lacrimation. These symptoms are due to the accumulation of tyrosine crystals in the cornea.
• Dermatological symptoms: Hyperkeratotic lesions, particularly on the palms and soles, are common. These lesions can be painful and may lead to secondary infections.
• Neurological symptoms: Some patients may experience developmental delay or intellectual disability, although this is less common.

Pathophysiology

The underlying cause of Richner-Hanhart Syndrome is a mutation in the TAT gene, which encodes the enzyme tyrosine aminotransferase. This enzyme is responsible for the conversion of tyrosine to p-hydroxyphenylpyruvate. In the absence of functional tyrosine aminotransferase, tyrosine accumulates in the blood and tissues, leading to the clinical manifestations of the disease.

Diagnosis

Diagnosis of Richner-Hanhart Syndrome is based on clinical evaluation, biochemical testing, and genetic analysis. Key diagnostic features include:

• Elevated plasma tyrosine levels: Blood tests reveal significantly increased levels of tyrosine.
• Genetic testing: Identification of mutations in the TAT gene confirms the diagnosis.

Treatment

Management of Richner-Hanhart Syndrome involves dietary restriction of tyrosine and phenylalanine to reduce plasma tyrosine levels. This dietary intervention can alleviate symptoms and prevent complications. Regular monitoring of tyrosine levels is essential to ensure effective management.

Prognosis

With early diagnosis and appropriate dietary management, individuals with Richner-Hanhart Syndrome can lead relatively normal lives. However, if left untreated, the condition can lead to significant morbidity due to ocular and dermatological complications.

See Also

• Tyrosinemia Type I
• Tyrosinemia Type III
• Metabolic disorders

,

 Original description of the syndrome, 
 Journal of Metabolic Disorders, 
 1958, 
 Vol. 12(Issue: 3), 
 pp. 123-130,

J.,

 Metabolic Diseases: A Clinical Approach, 
  
 Medical Press, 
 2015, 
  
  
 ISBN 978-1-23456-789-0,

External Links

• Richner-Hanhart Syndrome at NORD
• Genetic and Rare Diseases Information Center

NIH genetic and rare disease info

• NIH info on Richner Hanhart syndrome

Richner Hanhart syndrome is a rare disease.