This is part four in the series for Metabolic Disease Awareness Week. It focuses on Tyrosinaemia which is another inborn error of metabolism (metabolic disease) caused by a deficiency in fumaryl-acetoacetate hydrolase.
There are 3 types of this disorder:
- Tyrosinaemia Type I
- Tyrosinaemia Type II (Richner-Hanhart syndrome)
- Tyrosinaemia Type III.
Tyrosinaemia Type I is caused by a shortage of the enzyme: fumarylacetoacetate hydrolase. It has an incidence of approximately 1:100,000. The symptoms will appear in the first few months of life. These include:
- Failure to trive.
- Lethargy.
- Diarrhoea.
- Jaundice.
- Bleeding.
- Liver failure.
- Kidney failure.
Treatment is nutritional based, with a diet requiring a low phenylalanine and tyrosine: this generally means a low protein diet, with no fish, meat eggs or nuts. There is also the drug Nitisinone (NTBC) available.
Tyrosinaemia Type II is caused by a shortage of the enzyme: tyrosine aminotransferase. It has an incidence of approximately 1:250,000. The symptoms will appear in early childhood. These include:
- Corneal erosions and ulcers (resulting in sensitivity to light and pain to the eyes).
- Poor mental development.
- Palm and sole erosions.
Treatment again is nutritional based, and is similar to type I with a diet requiring a low phenylalanine and tyrosine.
Tyrosinaemia Type III is caused by a shortage of the enzyme: 4-hydroxyphenylpyruvate dioxygenase. It is very rare. The symptoms will appear in early childhood. These include:
- Seizures.
- Poor mental development.
- Loss of balance and coordination
It is another disorder that is inherited in a autosomal recessive manner. This means that the parents of the affected child carry a genetic trait that cause Tyrosinamemia.