PCSK9 and familial hypercholesterolemia: The common treatment for ameliorating hypercholesterolemia includes drugs of statins, ezetimibe, proprotein convertase subtilisin/kexin type 9 (PCSK9), and peroxisome proliferatively activated receptor (PPARα) inhibitors, achieving a good effect; however, its side-effects (e.g., diarrhea, memory dysfunction, and diabetes risk) should not be neglected [12,13].