Tyrosine is derived from ingested proteins or is synthesized in the body from phenylalanine. It is used for protein synthesis and is a precursor for many neurotransmitters and thyroxin. Normally, excess tyrosine is converted to carbon dioxide and water.
Hereditary causes of hypertyrosinemia include deficiencies of tyrosine aminotransferase, 4-hydroxyphenylpyruvate dioxygenase (4-HPPD) or fumarylacetoacetate hydrolase (FAH).
Affected infants appear normal at birth, this is because intrauterine metabolism was carried out by the mother. After birth, once the infant starts feeding, and can’t metabolize nutrients themselves, plasma levels of the contributing amino acid and/or amino acids increase and become toxic.
Tyrosinemia symptoms are Fever, irritability, vomiting, jaundice elevated levels of serum transaminases and hypoglycemia.
Tyrosinemia diagnosis is by the presence of elevated levels of succinylacetone in serum and in urine.
Tyrosinemia prevalence: Worldwide, tyrosinemia type I affects about 1 in 100,000 individuals. Tyrosinemia type II occurs in less than 1 in 250,000 individuals worldwide. Tyrosinemia type III is very rare; only a few cases have been reported.
Why Nutrition Management is important?
A diet low in phenylalanine and tyrosine can slow but doesn’t halt the progression of this condition. The treatment of choice is nitisinone, which inhibits tyrosine degradation at 4-HPPD.
A special diet is essential because tyrosine will remain in the body. This diet is based on foods that are low in tyrosine and phenylalanine. It is also known as a low protein diet and helps to control tyrosine levels in the blood. Tyrosine and phenylalanine are found in protein, so high-protein foods must be avoided to stop too much tyrosine building up in the body.
All children and teenagers need protein to be able to grow normally, so the protein that has been taken out of the diet needs to be replaced. This is done using protein supplements or protein substitutes. “For babies, all the protein (except tyrosine and phenylalanine), vitamins, and minerals needed for growth are provided in their special infant formula,”
For weight gain and development, additional sources of nutrition are essential. Protein free calorie rich formulae, nutridense and low protein foods can be given to meet 100-125% of the RDA per age.
Providing education and support for the family is the key to a successful long range of therapy. Effective treatment is best achieved by a team of specialists such as your Physician, Nutritionist, Geneticist, Neurologist, and Psychologist.
A healthy Tyrosinemia life expectancy can be foreseen with a wholesome approach with watchful diet, medical support and optimal nutrient supplement.