The transplanted Fah+/+ cells have a natural selective advantage over native mutant Fah-/- hepatocytes in clonally expanding and replacing diseased hepatocytes when NTBC is withdrawn from recipients, preventing fibrotic lesions and the development of HCC tumors caused by the accumulation of toxic metabolites, including succinylacetone, in the liver [26,27]. This evidence concerns the gene FAH and hepatocellular carcinoma.