About Tyrosinaemia (TYR)
Tyrosinaemia (TYR) is an inherited inborn error of metabolism resulting from a deficiency of different enzymes depending on the condition type, the enzymes catalyse the breakdown of tyrosine. Loss of enzyme activity in TYR Type I results in damages to the liver and kidneys and brain. In the case of Tyrosinaemia Type II, the deficiency in the relevant enzyme leads to the accumulation of tyrosine crystals in the eyes causing painful inflammation.
Major Signs and Symptoms
In the so-called acute form of the disease, abnormalities appear in the first month of life. Babies may show:
- poor weight gain
- enlarged liver and spleen
- distended abdomen
- swelling of the legs
- increased tendency to bleeding, particularly nose bleeds.
- Jaundice may or may not be prominent.
Despite vigorous therapy, death from hepatic failure frequently occurs between three and nine months of age unless a liver transplantation is performed.
Some children have a more chronic form of tyrosinemia with
- a gradual onset and less severe clinical features.
- enlargement of the liver and spleen are prominent
- the abdomen is distended with fluid
- weight gain may be poor
- vomiting and diarrhea occur frequently.
Affected patients usually develop cirrhosis and its complications. These children also require liver transplantation.
Incidence and Prevalence
Worldwide, tyrosinemia type I affects about 1 in 100,000 individuals.
Nutritional products provide necessary protein equivalents in the diets of individuals with TYR. Therapy should ideally be life-long in order to maximise disease control and minimise long-term adverse consequences.
Medical food should be consumed throughout the day and divided into at least 3 servings as more frequent consumption is associated with better phenylalanine and tyrosine tolerance and improved plasma tyrosine concentrations.
Importance of Compliance
Therapy should ideally be life-long in order to maximise disease control and minimise long-term adverse consequences, though adherence to therapy recommendations often diminishes with age emphasising the need to provide a range of supplements to provide variety in treatment options for individuals with TYR of all ages. Importantly, improvements in behaviour and functioning have been documented in previously untreated individuals with the condition who have been placed on diet therapy, demonstrating the importance of a range of nutritional product options for individuals, including those who may go ‘off diet’ for a period and later return to dietary therapy.
Providing additional, palatable therapy options is likely to enhance adherence to therapy, supporting the need for new formulations such as TYR Easy Shake & Go.
TYR Easy Shake & Go will be available from orpharma in the next 3 months.
Australian Department of Health and Ageing and National Health and Medical Research Council (2006). “Nutrient reference values for australia and new zealand including recommended dietary intakes.” Commonwealth of Australia.
Barnby E. Tyrosinemia type 1: an overview of nursing care. Pediatr Nurs. 2014 Mar-Apr;40(2):61-8, 90.
Genetics home reference. https://ghr.nlm.nih.gov/condition/tyrosinemia. Accessed 06 Apr 2016
Human Genetics Society of Australia. The Low Protein Handbook for Tyrosinemia. https://www.hgsa.org.au/documents/item/49. accessed 6 April 2016.
Malik S, NiMhurchadha S, Jackson C, Eliasson L, Weinman J, Roche S, Walter J. Treatment Adherence in Type 1 Hereditary Tyrosinaemia (HT1): A Mixed-Method Investigation into the Beliefs, Attitudes and Behaviour of Adolescent Patients, Their Families and Their Health-Care Team. JIMD Rep. 2015;18:13-22.
Orphanet: Tyrosinemia 2. http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Expert=28378. Accessed 06 Apr 2016