 Homozygous Familial Hypercholesterolemia HoFH is a rare genetic metabolic disorder characterized by absent or severely reduced capacity to catabolize circulating LDL particles by the hepatic LDL receptor. As a consequence, HoFH subjects present abnormal total plasma cholesterol LDL-C levels, resulting in severe atherosclerosis often leading to early onset of cardiovascular disease. Early initiation of aggressive treatment for these patients is therefore essential. Unfortunately, despite existing therapies, treated LDL-C levels could remain well above acceptable levels. Thus, the functional replacement of the defective LDLR via AAV-based liver-directed gene therapy may be a viable approach to treat this disease and improve response to current lipid-lowering treatments. This first-in-humans study is intended to evaluate the safety of this gene therapy investigational product and assess preliminary evidence of efficacy using plasma LDL-C levels as a surrogate biomarker for human LDLR transgene expression. 