NGGT006 Gene Therapy for Homozygous Familial Hypercholesterolemia

Inclusion Criteria: * Voluntarily sign informed consent form; * Male or female, 12 ≤ age ≤ 55 years (first patient≥ 18 years), diagnosed as homozygous familial hypercholesterolemia with genetic confirmation of two mutant alleles of the LDL receptor (LDLR) gene; * AAV8 neutralizing antibodies can be negative or reduced to negative levels through methods such as plasma exchange. * Untreated LDL-C ≥10 mmol/L (386mg/ dL) or treated LDL-C ≥7 mmol/L (270mg/ dL) together with cutaneous or tendon xanthoma before age 18 years; * Had been on stable medication for ≥30 days if receiving lipid-lowering therapy (or ≥60 days if receiving alirocumab or evolocumab) prior to screening and not scheduled for addition of new drugs or dose adjustments during the study; * Agreed to follow a low-fat diet and comply with all study procedures; * Agreed to maintain a similar exercise volume and intensity to baseline during the study period; * Agreed to maintain good lifestyle habits; * No history of alcohol abuse or alcohol dependence (diagnosed as F10 in ICD-10 code); * No sexual activity for 14 days prior to administration and negative serum pregnancy test in female participants; * Participants of childbearing potential agreed to use highly effective contraception for at least 365 days from administration of NGGT006; * No plan of stent implantation within 3 months. Exclusion Criteria: * Positive for hepatitis B surface antigen, hepatitis C, human immunodeficiency virus (HIV) or syphilis test; * Clinically significant abnormalities in liver function test: alanine aminotransferase (ALT) ≥2 × upper limit of normal (ULN) and/or aspartate aminotransferase (AST) ≥2 × ULN; * Baseline blood pressure ≥160/100 mmHg (1 repeat measurement is allowed); * Uncontrolled myocardial infarction or heart failure, or had surgery plan within 1 year; * Diabetes diagnosed within 3 months or with poor control (HbA1c ≥9%); * Acute or chronic kidney failure; * Hemoglobin (Hb) ≥120g/L (male), Hb ≥110 (female); * Abnormal platelet counts or morphology; * History or laboratory tests suggestive of thrombosis; * Had contraindications to glucocorticoid (e.g., epilepsy, severe schizophrenia, active peptic ulcer); * Life expectancy less than 1 year; * With malignant tumors; * Liver fibrosis or liver cancer; * Previous gene therapy treatment; * Hypersensitivity to AAV or cortisone or immunosuppressants (sirolimus, rituximab, tacrolimus); * Participation in any other clinical trial within 3 months; * History of stent implantation within 1 month or myocardial infarction within 3 months; * Breastfeeding females; * Any other condition that may not be appropriate for the study in the opinion of the Investigator.