Hereditary tyrosinemia type 1 (HT1) is caused by a deficiency in fumarylacetoacetate hydrolase (FAH) resulting in acute liver failure, neurologic crisis, HCC, and early death.1 HT1 is treated with the drug 2-(2-nitro-4-trifluoro-methylbenzyol)-1,3 cyclohexanedione (NTBC), also known as nitisinone, to inhibit the enzyme 4-hydroxyphenylpyruvate dioxygenase (Hpd), and block the buildup of downstream toxic metabolites.1 NTBC is combined with dietary restrictions of tyrosine and phenylalanine to lower tyrosine levels and prevent disease symptoms. The gene discussed is HPD; the disease is hepatocellular carcinoma.