Tyrosinemia Type 1 is an inherited metabolic disorder in which the body lacks an enzyme called fumarylacetoacetate hydrolase (FAH). This enzyme is important in breaking down the amino acid tyrosine. A deficiency of FAH results in increased levels of tyrosine in blood and several different tissues and organs. There are several types of tyrosinemia, but type 1 is the most severe. Symptoms begin during the first few months of life and include failure to thrive, diarrhea, vomiting, yellowing of the skin and eyes (jaundice), an enlarged liver, and an unusual odor described as boiled cabbage smell. The kidneys, central nervous system, lungs, and bones can also be affected. If not recognized or treated promptly, tyrosinemia type 1 is usually fatal before age 10. However, with treatment and a low-tyrosine diet, approximately 90% of affected individuals will live to adulthood and experience a fairly normal life. Tyrosinemia Type 1 is caused by pathogenic variants in the FAH gene.