Tyrosinemia Type III
Description
Tyrosinemia Type III, also known as ‘Richner-Hanhart syndrome‘, is a rare genetic disorder that affects the body‘s ability to break down the amino acid tyrosine. This condition can lead to various symptoms, primarily affecting the skin, eyes, and nervous system.
Genes Involved
Genes Involved:
- Tyrosinemia Type III is caused by mutations in the HPD gene. This gene provides instructions for making the enzyme 4-hydroxyphenylpyruvate dioxygenase (4-HPPD). This enzyme is crucial for breaking down tyrosine in the body.
Recognizing the Signs and Symptoms
Recognizing the Signs and Symptoms:
- Skin problems: The most noticeable symptom is the development of thick, calloused skin on the palms of the hands and soles of the feet, often with deep cracks. These areas may also be covered in blisters and sores.
- Eye issues: Affected individuals may experience corneal clouding (opacity of the cornea), which can lead to vision problems.
- Neurological problems: Some people with Tyrosinemia Type III may experience developmental delays, seizures, and intellectual disability.
- Other symptoms: Other possible symptoms include hair loss, excessive sweating, and a distinctive body odor.
Causes
Causes:
- Tyrosinemia Type III is inherited in an autosomal recessive manner. This means that both parents must carry a copy of the mutated gene for their child to have the condition.
- If both parents carry the mutated gene, there is a 25% chance that their child will inherit the disorder.
Inheritance/recurrence risk
Inheritance or Recurrence Risk:
- Autosomal Recessive Inheritance: Tyrosinemia Type III is passed down through generations via autosomal recessive inheritance. This means that an individual must inherit two copies of the mutated gene, one from each parent, to develop the disorder.
- Recurrence Risk: If both parents are carriers of the mutated gene, there is a 25% chance with each pregnancy that their child will inherit Tyrosinemia Type III.
