This is an early phase 1, open-label, single-center, dose-escalation pilot trial to evaluate the safety and efficacy of an intravenous infusion of NGGT006 in patients with refractory Hypercholesterolemia diagnosed by gene testing for familial hypercholesterolemia. NGGT006 uses adeno-associated virus (AAV) as a vector, carrying a liver specific promoter and codon optimized human LDLR gene, driving the expression of LDLR protein with normal function and promoting the clearance of low-density lipoprotein cholesterol (LDL-C).