Additionally, Pcsk9−/− mice showed an increase in liver lipid accumulation and CD36 expression, and when subjected to HFD, these mice developed severe liver steatosis and fibrosis.109,185 This ground-breaking research suggested that PCSK9 could degrade CD36 through interaction with its extracellular loop and mediation of its internalization. The gene discussed is PCSK9; the disease is fatty liver disease.