Tyrosinemia type I (MIM# 276700; TYRSN1, TYR I) is an inborn error of tyrosine metabolism caused by pathogenic variants in fumarylacetoacetate hydrolase (FAH; MIM# 613871, EC 3.7.1.2), the final enzyme in the tyrosine degradation cascade [Grompe, 2001]. This evidence concerns the gene FAH and Tyrosinemia type 1.