Based on morphological and immunophenotypical traits, HCAs are categorized into five main subtypes: inflammatory HCA, β-catenin mutant HCA, sonic hedgehog HCA, hepatocyte nuclear factor-1 alpha (HNF-1α) inactivated HCA (H-HCA), and unclassified HCA. The gene discussed is HNF1A; the disease is hepatocellular adenoma.