Hereditary tyrosinemia type 1 (HT1) is caused by deficiency of the final enzyme in Phe/Tyr catabolism pathway, fumarylacetoacetate hydrolase (FAH), and is characterized by progressive liver diseases with increased risk for HCC (Weinberg et al, 1976; Van Spronsen et al, 1994). The gene discussed is FAH; the disease is liver disorder.