• 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.