PCSK9 and triple-A syndrome: Furthermore, previous clinical studies reported that proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors can reduce AAA risk, and PCSK9 inhibitors can reduce low-density lipoprotein cholesterol (LDL) by inhibiting degradation of the LDL receptor, whereas mutations in PCSK9 aggravated AAA development in mice187.