Not only are there people with SNPs that promote hypo-PCSK9, and so 'familial hypercholesterolemia', but there are also people with SNPs that promote hyper-PCSK9, and so very low levels of LDL (not zero - having very efficient scavenging reduces "dwell time" but does not block production).

My first thought was how do people survive without cholesterol - something necessary for cellular processes, hormone creation, etc. It turns out that bringing LDL to a very low level only reduces overall cholesterol by... (10%? - sorry can't find the study right now) - these people are quite healthy and have very reduced risk for arteriosclerosis. There are plenty of other mechanisms of transport, notably RBCs — and cells produce their own cholesterol.

It's worth remembering that there are many different SNPs associated with familial arteriosclerosis - low PSCK9 is just one of them.

BTW/FWIW Berberine, like Metformin is a very mild ECT inhibitor, but unlike Metformin, it's also a mild PCSK9 inhibitor. Worth a try if you've got high LDL that statins cannot bring down (and don't start me on statins... :-)