LDLR and familial hyperaldosteronism: More recent studies have identified a natural LDLR inhibitor, proprotein convertase subtilisin kexin type 9 (PCSK9), which regulates the LDLR secretory pathway by stimulating degradation of LDLRs.[22] Mutations in the PCSK9 gene impair LDLR endocytosis in FH.[23,24] Hepatic PCSK9 expression is regulated by insulin and SREBP-1C.[25]