Congenital metabolic disease: tyrosinemia Metabolism consists of the different processes and reactions catalyzed by enzymes that the body uses to produce energy. 1 Proteins, carbohydrates, fats and amino acids are used to produce the sugars and acids needed to fuel the body with the components needed to sustain life. 1 The body can then store this energy in tissues, mainly in the liver and muscles, or it can store it in the form of body fat. This body fat can then serve as a reserve or can be used directly when needed. Metabolic disorders occur when atypical chemical reactions occur that prevent life processes from producing normally necessary products. 2 They can also occur by preventing the body from controlling a normal level of a certain chemical, which in turn can negatively affect a person's liver, muscles, and heart. 2 The metabolic disorder that will be examined in this article is tyrosinemia. Tyrosinemia is a metabolic disorder characterized by increased levels of the amino acid tyrosine in the blood. 3 This is due to the deficiency of a specific enzyme that is part of the multi-step process of tyrosine degradation. This leads to a buildup of the amino acid which subsequently wreaks havoc on the body's organs. 3 There are three main types of tyrosinemia: tyrosinemia type I, tyrosinemia type II and tyrosinemia type III3. Each type is different in symptoms, severity, and the defective enzyme. The amino acid involved in this disorder is tyrosine. Tyrosine is one of the most insoluble amino acids4. It comes from two sources, diet and the hydroxylation of phenylalanine. 4 Tyrosine degradation is a catabolic pathway. Catabolic pathways are used to break down larger substances… half of paper… 21/2014)2. http://www.mayoclinic.org/diseases-conditions/inherited-metabolic-disorders/basics/definition/con-20036708 (accessed 04/21/2014)3. http://emedicine.medscape.com/article/949816 Overview#a0104 (accessed 04/21/2014)4. Fernandes, J. Saudubray, J. van den Berghe, G. Congenital metabolic diseases, 4th ed. Germany, Springer Medizin Verlag Heidelberg 2000, 2006; pp 234-240.5. https://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/aacarbon.htm (accessed 04/21/2014)6. http://www.ncbi.nlm.nih.gov/books/NBK1515/ (accessed 04/21/2014)7. http://www.pnas.org/content/96/21/11928/F1.large.jpg (Figure 1.) (accessed 04/22/2014)8. van Spronsen, F.J. Thomasse, Y. Smit GP. Leonard, J. Clayton, PT, Fidler, V. Berger, R. Heymans, H. Hereditary tyrosinemia type I: a new clinical classification with difference in prognosis on dietary treatment. Hepatology. 1994, 20, 1187–1191.