Human embryo editing: Who wants which genetic changes to be allowed?

International Society for Stem Cell Research (ISSCR) · Research without implantation

ISSCR places genetic alteration of human embryos in its reviewable Category 2: it can proceed after specialized scientific and ethics approval, while edited embryos may not be used for reproduction.

Preclinical research that entails modifying the nuclear genomes of gametes, zygotes, and human embryos may be permissible under a rigorous specialized oversight process.

International Society for Stem Cell Research (ISSCR) · Severe single-gene disease

ISSCR says reproductive embryo editing is premature today. If technical and safety barriers are resolved, first uses should be case-by-case and concentrated where mortality or morbidity is severe and prospective parents lack reasonable alternatives.

International Society for Stem Cell Research (ISSCR) · Broader disease-risk reduction

For initial clinical use, ISSCR points to severe disease, a favorable harm-benefit balance and lack of reasonable alternatives. That boundary excludes common or medically manageable risk reduction from the initial-use category defined here.

International Society for Stem Cell Research (ISSCR) · Non-medical enhancement

ISSCR confines the contemplated first-in-human pathway to serious disease contexts with strong medical need and no reasonable alternatives; non-medical trait enhancement therefore falls outside this initial reproductive-use boundary.

International Commission on the Clinical Use of Human Germline Genome Editing · Severe single-gene disease

If a country decides to permit heritable editing, the Commission says initial uses should be limited to serious monogenic diseases, correction to a common non-disease sequence, and families with no or exceptionally poor alternatives, after demanding safety evidence.

the use of HHGE is limited to serious monogenic diseases

International Commission on the Clinical Use of Human Germline Genome Editing · Broader disease-risk reduction

The Commission states that its responsible initial translational pathway is limited to serious monogenic disease. Other classes of use require separate future evaluation before any threshold to permission is crossed.

International Commission on the Clinical Use of Human Germline Genome Editing · Non-medical enhancement

The Commission’s initial pathway is expressly limited to serious monogenic disease. Moving to any new class of use would require a separate international evaluation and a newly justified translational pathway.

Medical Ethics Subcommittee of China’s National Science and Technology Ethics Committee · Research without implantation

China’s ethics guidance sets conditions for genome-editing research involving germ cells, fertilized eggs and in-vitro human embryos, while strictly prohibiting use of edited material for pregnancy or reproduction.

严禁将编辑后的生殖细胞、受精卵或人胚用于妊娠及生育。

Medical Ethics Subcommittee of China’s National Science and Technology Ethics Committee · Severe single-gene disease

The guidance says all germline clinical research is currently irresponsible and not permitted. It allows future consideration only after benefits, risks and alternatives are understood, safety and efficacy are resolved, broad consensus exists and strict supervision is in place.

Medical Ethics Subcommittee of China’s National Science and Technology Ethics Committee · Broader disease-risk reduction

The guidance restricts clinical genome-editing research to medical treatment or prevention and says germline trials are not currently allowed. It does not specify whether future eligibility would extend from severe monogenic disease to common or polygenic risk reduction.

Medical Ethics Subcommittee of China’s National Science and Technology Ethics Committee · Non-medical enhancement

The guidance says clinical genome-editing research must be limited to treatment or prevention and prohibits non-medical genetic changes; it also warns that permanent genetic enhancement may harm dignity and worsen inequality.

Nuffield Council on Bioethics · Severe single-gene disease

Nuffield’s framework allows heritable editing only after broad public debate, safety research, social-risk assessment and strict case-by-case regulation, and its joint statement says serious hereditary disease can be morally permissible.

Nuffield Council on Bioethics · Broader disease-risk reduction

Nuffield does not classify uses as acceptable or unacceptable solely by category. Broader medical uses remain conditionally assessable case by case, provided future-person welfare and social-justice principles are met alongside safety and governance requirements.

Nuffield Council on Bioethics · Non-medical enhancement

Unlike CCNE, Nuffield rejects a fixed categorical therapy-versus-enhancement boundary. A use could only be considered through case-by-case assessment of future-person welfare, disadvantage, discrimination, social division, safety and public legitimacy.

Comité Consultatif National d’Éthique (CCNE) · Severe single-gene disease

The joint statement of the French, German and UK ethics councils says all three can conceive morally permissible cases and identify prevention of serious hereditary disorders as such a possible use, subject to prior safety, societal debate and governance.

Comité Consultatif National d’Éthique (CCNE) · Non-medical enhancement

The joint statement distinguishes CCNE from the other councils by recording its categorical ethical opposition to enhancement applications of heritable genome editing.

the CCNE expresses a complete ethical opposition to ‘enhancement’ applications.

Center for Genetics and Society · Research without implantation

CGS has repeatedly called on scientists to avoid research designed to refine heritable reproductive editing and criticizes recent embryo-editing work for pushing toward engineered births. Its cited statements do not resolve its position on all basic non-reproductive editing.

refrain from research aimed at refining gene editing for use in human reproduction

Center for Genetics and Society · Severe single-gene disease

CGS argues that heritable editing remains unsafe and unnecessary because alternatives such as embryo screening exist, and calls for stronger prohibitions rather than a clinical pathway for disease correction.

heritable human genome editing is unnecessary

Center for Genetics and Society · Broader disease-risk reduction

Because CGS opposes heritable reproductive genome editing as unnecessary and socially dangerous, its rejection applies beyond severe single-gene disease to broader medical risk reduction as well.

Center for Genetics and Society · Non-medical enhancement

CGS argues for prohibiting human germline modification and warns that a disease-treatment boundary is difficult to maintain against enhancement and other attempts to control traits of future generations.

Cathy Tie · Research without implantation

Tie argues against delaying embryo-editing research and says Origin is developing base- and prime-editing approaches using research-donated embryos or embryonic stem-cell models while she acknowledges the technology is not ready for patients.

Cathy Tie · Severe single-gene disease

Tie argues that germline editing should move toward new clinical and regulatory pathways for inherited disease; Origin’s stated ethical focus is on well-characterized severe diseases that cause suffering.

Cathy Tie · Broader disease-risk reduction

Tie says Origin’s ethics position is to focus on diseases that are well characterized, severe and cause suffering, excluding broader common or manageable risk reduction from the company’s current clinical boundary.

Cathy Tie · Non-medical enhancement

In her September 2026 position, Tie supports disease prevention as reproductive choice but draws a line against using the technology for non-medical trait enhancement such as intelligence.

Lucas Harrington · Research without implantation

Harrington founded Preventive to determine through preclinical work whether gene editing can safely prevent severe genetic disease, with clinical applications considered only after extensive safety research.

conduct thorough preclinical research evaluating safety before considering any clinical applications

Lucas Harrington · Severe single-gene disease

Preventive’s stated focus is severe genetic disease in families with limited or no alternatives. Harrington says the company will not advance to human clinical use unless extensive research establishes safety.

Lucas Harrington · Broader disease-risk reduction

Preventive defines its present research mission around severe genetic disease and limited alternatives. The announcement does not say whether Harrington would support or reject broader disease-risk editing if the technology later became safe.

I. Glenn Cohen · Research without implantation

In an April 2026 debate, Cohen and Cathy Tie agreed that embryo editing is not inherently unethical and that laboratory research on embryos can be ethically justified.

I. Glenn Cohen · Severe single-gene disease

Cohen agreed that if clinical use becomes ethical, it should start with serious diseases associated with a single gene. His support remains conditional on unresolved safety, governance and ethical requirements.

I. Glenn Cohen · Broader disease-risk reduction

Cohen explicitly asks when, if ever, it would be appropriate to move from debilitating, life-shortening initial targets to other diseases. He does not supply a general yes-or-no rule.

When, if ever, would it be appropriate to move from that small number of targets to other diseases?

I. Glenn Cohen · Non-medical enhancement

Cohen distinguishes optimization from avoiding serious disease and asks whether enhancement uses could ever be appropriate, leaving the categorical answer open.

Julian Savulescu · Severe single-gene disease

Savulescu and co-authors argue that when preimplantation selection cannot produce an unaffected embryo and the alternative is severe suffering or early death, the expected benefits can justify heritable editing under stringent safeguards.

heritable editing is permissible, and the duty of beneficence toward future persons may require it.

Julian Savulescu · Broader disease-risk reduction

The 2026 analysis separates polygenic risk reduction from catastrophic monogenic disease and concludes that insufficient predictive validity and poorly understood pleiotropic effects make clinical use premature.

current scientific uncertainty makes clinical application premature

Julian Savulescu · Non-medical enhancement

The analysis describes the case for enhancement as weaker still, citing positional benefits and social-stratification risks, and argues that governance should prohibit uses unsupported by evidence.

For enhancement, the case is weaker still.

Cheyenne Ziegler · Severe single-gene disease

After IVF to avoid a Charcot-Marie-Tooth variant, Ziegler and her partner kept affected embryos in hope that correction becomes possible. Her statement is a personal preference in a serious inherited-disease context, not a general regulatory proposal.

If the choices are to discard or to give a new technology a chance, I would lean toward giving new technology a chance