Table 1.

Category of applications of HHGE and the recommendation from International Commission on the Clinical Use of Human Germline Genome Editing.

Category	Definition	Characteristics	Recommendation
A	Serious monogenic Diseases Heritability: 100%	◆ Autosomal dominant disease (one parent carries affected homozygote) ◆ Autosomal recessive disease (both parents carry affected homozygotes) ◆ X-linked recessive diseases (female parent carries affected homozygote, male parent carries affected hemizygote)	All is suitable for HHGE
B	Serious monogenic Diseases Heritability: 25–50%	◆ Autosomal dominant disease (one parent carries affected heterozygote) ◆ Autosomal recessive disease (both parents carry affected heterozygotes) ◆ X-linked dominant disease (female parent carries affected heterozygote) ◆ X-linked recessive diseases (female parent carries affected heterozygote, male parent carries affected hemizygote)	A small subset is suitable for HHGE
C	Mild monogenic diseases	Mainly affecting quality of life; Could be mitigated by medical or lifestyle interventions e.g., familial hypercholesterolemia	Unsuitable for HHGE, because the balance of risks and benefits is unknown
D	Polygenic diseases	Disease were caused by a large number of genetic variants e.g., T2DM
E	Other applications	Enhancing human ability, or obtaining new function
F	Monogenic conditions that cause infertility	Treating e infertility caused by monogenic variant in germline cell

HHGE, Heritable Human Genome Editing.