Feb. 14, 2017




With Stringent Oversight, Heritable Germline Editing Clinical Trials Could One Day Be Permitted for Serious Conditions; Non-Heritable Clinical Trials Should Be Limited to Treating or Preventing Disease or Disability at This Time


WASHINGTON – Clinical trials for genome editing of the human germline – adding, removing, or replacing DNA base pairs in gametes or early embryos – could be permitted in the future, but only for serious conditions under stringent oversight, says a new report from the National Academy of Sciences and the National Academy of Medicine.  The report outlines several criteria that should be met before allowing germline editing clinical trials to go forward.  Genome editing has already entered clinical trials for non-heritable applications, but should be allowed only for treating or preventing diseases or disabilities at this time.


Genome editing is not new.  But new powerful, precise, and less costly genome editing tools, such as CRISPR/Cas9, have led to an explosion of new research opportunities and potential clinical applications, both heritable and non-heritable, to address a wide range of human health issues.  Recognizing the promise and the concerns related to this technology, NAS and NAM appointed a study committee of international experts to examine the scientific, ethical, and governance issues surrounding human genome editing.


Human genome editing is already widely used in basic research and is in the early stages of development and trials for clinical applications that involve non-heritable (somatic) cells.  These therapies affect only the patient, not any offspring, and should continue for treatment and prevention of disease and disability, using the existing ethical norms and regulatory framework for development of gene therapy.  Oversight authorities should evaluate safety and efficacy of proposed somatic applications in the context of the risks and benefits of intended use.


However, there is significant public concern about the prospect of using these same techniques for so-called “enhancement” of human traits and capacities such as physical strength, or even for uses that are not possible, such as improving intelligence.  The report recommends that genome editing for enhancement should not be allowed at this time, and that broad public input and discussion should be solicited before allowing clinical trials for somatic genome editing for any purpose other than treating or preventing disease or disability. 


“Human genome editing holds tremendous promise for understanding, treating, or preventing many devastating genetic diseases, and for improving treatment of many other illnesses,” said Alta Charo, co-chair of the study committee and Sheldon B. Lubar Distinguished Chair and Warren P. Knowles Professor of Law and Bioethics, University of Wisconsin-Madison.  “However, genome editing to enhance traits or abilities beyond ordinary health raises concerns about whether the benefits can outweigh the risks, and about fairness if available only to some people." 


Germline genome editing, in contrast, is contentious because genetic changes would be inherited by the next generation.  Many view germline editing as crossing an “ethically inviolable” line, the report says.  Concerns raised include spiritual objections to interfering with human reproduction to speculation about effects on social attitudes toward people with disabilities to possible risks to the health and safety of future children.  But germline genome editing could provide some parents who are carriers of genetic diseases with their best or most acceptable option for having genetically related children who are born free of these diseases. 


Heritable germline editing is not ready to be tried in humans.  Much more research is needed before it could meet the appropriate risk and benefit standards for clinical trials.  The technology is advancing very rapidly, though, making heritable genome editing of early embryos, eggs, sperm, or precursor cells in the foreseeable future “a realistic possibility that deserves serious consideration,” the report says.  Although heritable germline genome editing trials must be approached with caution, the committee said, caution does not mean prohibition.


At present, heritable germline editing is not permissible in the United States, due to an ongoing prohibition on the U.S. Food and Drug Administration's ability to use federal funds to review “research in which a human embryo is intentionally created or modified to include a heritable genetic modification.”  A number of other countries have signed an international convention that prohibits germline modification.


If current restrictions are removed, and for countries where germline editing would already be permitted, the committee recommended stringent criteria that would need to be met before going forward with clinical trials.  They include: (1) absence of reasonable alternatives; (2) restriction to editing genes that have been convincingly demonstrated to cause or strongly predispose to a serious disease or condition; (3) credible pre-clinical and/or clinical data on risks and potential health benefits; (4) ongoing, rigorous oversight during clinical trials; (5) comprehensive plans for long-term multigenerational follow-up; (6) continued reassessment of both health and societal benefits and risks, with wide-ranging, ongoing input from the public; and (7) reliable oversight mechanisms to prevent extension to uses other than preventing a serious disease or condition.


Policymaking surrounding human genome editing applications should incorporate public participation, and funding of genome editing research should include support to study the socio-political, ethical, and legal aspects and evaluate efforts to build public communication and engagement on these issues.


The report recommends a set of overarching principles that should be used by any nation in governing human genome editing research or applications:



“Genome editing research is very much an international endeavor, and all nations should ensure that any potential clinical applications reflect societal values and be subject to appropriate oversight and regulation,” said committee co-chair Richard Hynes, Howard Hughes Medical Institute Investigator and Daniel K. Ludwig Professor for Cancer Research, Massachusetts Institute of Technology.  “These overarching principles and the responsibilities that flow from them should be reflected in each nation’s scientific community and regulatory processes.

Such international coordination would enhance consistency of regulation.”


The study was funded by the Defense Advanced Research Projects Agency, the Greenwall Foundation, the John D. and Catherine T. MacArthur Foundation, U.S. Department of Health and Human Services, U.S. Food and Drug Administration, and the Wellcome Trust, with additional support from the National Academies’ Presidents’ Circle Fund and the National Academy of Sciences W.K. Kellogg Foundation Fund.  The National Academy of Sciences and the National Academy of Medicine are private, nonprofit institutions that, along with the National Academy of Engineering, provide independent, objective analysis and advice to the nation to solve complex problems and inform public policy decisions related to science, technology, and medicine.  The Academies operate under an 1863 congressional charter to the National Academy of Sciences, signed by President Lincoln.  For more information, visit www.national-academies.org.


Copies of Human Genome Editing: Science, Ethics, and Governance are available at www.nap.edu or by calling 202-334-3313 or 1-800-624-6242.  Reporters may obtain a copy from the Office of News and Public Information (contacts listed above).



Molly Galvin, Senior Media Officer

Rebecca Ray, Media Assistant

Office of News and Public Information

202-334-2138; e-mail news@nas.edu


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Committee on Human Gene Editing: Scientific, Medical, and Ethical Considerations

Alta Charo1 (co-chair)

Sheldon B. Lubar Distinguished Chair and Warren P. Knowles Professor of Law and Bioethics

University of Wisconsin



Richard O. Hynes1,2 (co-chair)


Howard Hughes Medical Institute, and

Daniel K. Ludwig Professor for Cancer Research

Massachusetts Institute of Technology



David W. Beier

Managing Director

Bay City Capital

San Francisco


Ellen Wright Clayton1

Craig Weaver Professor of Pediatrics, and

Professor of Law

Vanderbilt University

Nashville, Tenn.


Barry S. Coller1,2

David Rockefeller Professor of Medicine,

Physician in Chief, and


Allen and Frances Adler Laboratory of Blood and Vascular Biology

Rockefeller University

New York City


John H. Evans


University of California

San Diego


Juan Carlos Izpisua Belmonte


Gene Expression Laboratory

Salk Institute for Biological Studies

La Jolla, Calif.


Rudolf Jaenisch1,2

Professor of Biology

Massachusetts Institute of Technology



Jeffrey Kahn1

Andreas C. Dracopoulos Director

Johns Hopkins Berman Institute of Bioethics

Johns Hopkins University



Ephrat Levy-Lahad


Fuld Family Department of Medical Genetics

Shaare Zedek Medical Center

Faculty of Medicine

Hebrew University of Jerusalem



Robin Lovell-Badge

Senior Group Leader

Laboratory of Stem Cell Biology and Developmental Genetics

The Francis Crick Institute



Gary Marchant

Regents’ Professor of Law

Arizona State University



Jennifer Merchant

University Professor

Université de Paris II (Panthéon-Assas)

Issy-les-Moulineaux, France


Luigi Naldini

Professor of Cell and Tissue Biology and of Gene and Cell Therapy

San Raffaele University, and


San Raffaele Telethon Institute for Gene Therapy



Duanqing Pei

Professor and Director General

Guangzhou Institute of Biomedicine and Health

Chinese Academy of Sciences

Guangzhou, China


Matthew Porteus

Associate Professor of Pediatrics

Stanford School of Medicine

Stanford, Calif.


Janet Rossant2

Senior Scientist and Chief of Research Emeritus

Hospital for Sick Children

University of Toronto



Dietram A. Scheufele

John E. Ross Professor in Science Communication and Vilas Distinguished Achievement Professor

University of Wisconsin



Ismail Serageldin2

Founding Director

Bibliotheca Alexandrina

Alexandria, Egypt


Sharon Terry

President and CEO

Genetic Alliance

Washington, D.C.


Jonathan Weissman2


Department of Cellular and Molecular Pharmacology

University of California

San Francisco


Keith R. Yamamoto1,2

Vice Chancellor for Science Policy and Strategy

University of California

San Francisco




Katie Bowman

Study Director


1Member, National Academy of Medicine

2Member, National Academy of Sciences