Tyrosinemia Type 1

Tyrosinemia type 1 is a genetic disorder characterized by elevated blood levels of the amino acid tyrosine, a building block of most proteins. This condition is caused by a shortage of the enzyme fumarylacetoacetate hydrolase, one of the enzymes required for the multi-step process that breaks down tyrosine. This enzyme shortage is caused by mutations in the FAH gene. Symptoms usually appear in the first few months of life and include failure to thrive, diarrhea, vomiting, jaundice, cabbage-like odor, and increased tendency to bleed (particularly nosebleeds). Tyrosinemia type I can lead to liver and kidney failure, softening and weakening of the bones, problems affecting the nervous system, and an increased risk of liver cancer. This condition is inherited in an autosomal recessive manner. Treatment should be started as soon as the condition is diagnosed and includes a diet restricted in tyrosine and phenylalanine along with nitisinone, a medication that blocks the second step in the tyrosine degradation pathway.