Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive liver disease now targeted by new pharmacotherapies, including the thyroid hormone receptor beta (THR-β) agonist resmetirom, glucagon-like peptide-1 (GLP-1) receptor agonists (semaglutide, liraglutide), and the dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptor agonist tirzepatide. The gene discussed is THRB; the disease is metabolic dysfunction-associated steatohepatitis.