In an article published in American Journal of Human Genetics on 3 August 2017, an international group of 11 organisations with genetics expertise has issued a joint position statement, setting out 3 key positions on the question of human germline genome editing:
(1) At this time, given the nature and number of unanswered scientific, ethical, and policy questions, it is inappropriate to perform germline gene editing that culminates in human pregnancy.
(2) Currently, there is no reason to prohibit in vitro germline genome editing on human embryos and gametes, with appropriate oversight and consent from donors, to facilitate research on the possible future clinical applications of gene editing. There should be no prohibition on making public funds available to support this research.
(3) Future clinical application of human germline genome editing should not proceed unless, at a minimum, there is (a) a compelling medical rationale, (b) an evidence base that supports its clinical use, (c) an ethical justification, and (d) a transparent public process to solicit and incorporate stakeholder input.
This serendipitously timed statement comes on the heels of Shoukhrat Mitalipov and colleagues at Oregon Health and Science University’s publication of an article in Nature reporting the successful use of CRISPR/Cas9 in human embryos to correct a mutation in a gene called MYBPC3 that causes a potentially fatal heart condition known as hypertrophic cardiomyopathy. The publication of this article has drawn the attention of the wider mainstream media and reignited the public debate as to the desirability, feasibility and ethics of editing the human genome in an inheritable way.
Gene editing - putting the paper in context
Whilst debates about the ethics of gene editing (both somatic and germline) go back decades, human germline genome editing has never before been realistically possible from a technical standpoint. That has changed with the advent of the CRISPR/Cas9 system, whose efficiency and ease of use has not only opened up the field of gene editing to a far larger number of companies and laboratories than previously, but has brought the editing of specific genes in a human embryo out of the realms of fantasy into reality. The potential for such technology to improve quality of life and prevent suffering caused by debilitating genetically inherited diseases has captured the imagination of many, particularly people living with currently intractable genetic conditions, their friends and family. However, the power of the technology has also conjured up the familiar spectres of “playing God”, the uncertainty of long term effects on individuals (and what it means to be human itself), marginalisation of the disabled or “genetically inferior” and the potential for inequality to manifest itself genetically as well as socioeconomically.
Germline cell editing poses significantly more concerning ethical and regulatory issues than somatic cell editing. The latter will only result in uninheritable changes to the genome of a population of cells in the particular individual treated, whilst the former involves genetic changes that will be passed down, for better or worse, to the individual’s offspring.
In early 2015, the first study demonstrating that CRISPR/Cas9 could be used to modify genes in early-stage human embryos was published. Although the embryos employed for those experiments were not capable of developing to term, the work clearly demonstrated that genome editing with CRISPR/Cas9 in human embryos can readily be performed. That report stimulated many scientists and organisations to clarify their stance on the use of genome-editing methods. The United Kingdom and Sweden have both approved experiments for editing DNA of a human embryo but not those that involve implanting embryos. In the UK, Human Fertilisation and Embryology Authority (HFEA) has approved an application by developmental biologist Kathy Niakan, at the Francis Crick Institute in London, to use CRISPR/Cas9 in healthy human embryos. Currently, such experiments cannot be done with federal funding in the United States given a congressional prohibition on using taxpayer funds for research that destroys human embryos. Congress has also banned the U.S. Food and Drug Administration from considering a clinical trial of embryo editing. As would be expected, the safety requirements for any human clinical genome-editing application are extremely stringent.
However, earlier this year, US-based National Academy of Sciences (NAS) and the National Academy of Medicine (NAM), published a report that concluded using genome-editing technology, such as CRISPR/Cas9, to make alterations to the germline would be acceptable if the intention was to treat or prevent serious genetic disease or disorders, and the procedure was proven to be safe ( significant and, to an extent, subjective hurdles to be overcome).
The ASHG position paper
The position paper was the product of a working group established by the American Society of Human Genetics (ASHG), including representatives from the UK Association of Genetic Nurses and Counsellors, Canadian Association of Genetic Counsellors, International Genetic Epidemiology Society, and US National Society of Genetic Counsellors. These groups, as well as the American Society for Reproductive Medicine, Asia Pacific Society of Human Genetics, British Society for Genetic Medicine, Human Genetics Society of Australasia, Professional Society of Genetic Counsellors in Asia, and Southern African Society for Human Genetics, endorsed the final statement. The group, composed of a combination of research and clinical scientists, bioethicists, health services researchers, lawyers and genetic counsellors, worked together to integrate the scientific status of and socio-ethical views towards human germline genome editing.
As part of this process, the working group reviewed and summarised nine existing policy statements on gene editing and embryo research and interventions from national and international bodies, including The International Society for Stem Cell Research (2015) Statement on Human Germline Genome Modification, The Hinxton Group (2015) Statement on Genome Editing Technologies and the statement released following the International Summit on Human Gene Editing (2015) co-hosted by the National Academy of Sciences, National Academy of Medicine, Chinese Academy of Sciences and The Royal Society (UK). It was observed that differences in these policies include the very definition of what constitutes a human embryo or a reproductive cell, the nature of the policy tool adopted to promote the positions outlined, and the oversight/enforcement mechanisms for the policy. However, by and large, the majority of available statements and recommendations restrict applications from attempting to initiate a pregnancy with an embryo or reproductive cell whose germline has been altered. At the same time, many advocate for the continuation of basic research (and even preclinical research in some cases) in the area. One notable exception is the US National Institutes of Health, which refuses to fund the use of any gene-editing technologies in human embryos. Accordingly, due to the lack of public funding in the US, work such as that done by Mitalipov’s group must be privately funded.
The working group considered that ethical issues around germline genome editing largely fall into two broad categories – those arising from its potential failure and those arising from its success. Failure exposes individuals to a variety of health consequences, both known and unknown, while success could lead to societal concerns about eugenics, social justice and equal access to medical technologies.
The 11 organisations acknowledged numerous ethical issues arising from human germline genome editing, including:
- exposing individuals to potentially harmful health consequences, since the magnitude of the potential risks of off-target or unintended consequences are yet to be determined;
- the risk that if highly restrictive policies are placed on the conduct and public funding of basic research in the field, this could push research out of the public eye and public interest, underground – to private funders or overseas, to organisations and territories where it would be subject to less regulation, transparency and oversight. This could result in research not being subject to ethical and peer oversight, such as ethics board approval, data sharing, peer review and dissemination of research resources;1
- the de facto inability of future individuals who are the result of genetic editing, to consent to that editing;
- concerns around the boundaries of eugenic use of gene editing technology, which the groups acknowledged “could be used to reinforce prejudice and narrow definitions of normalcy in our societies”; and
- ensuring the gene editing technologies do not worsen existing or create new inequalities within and between societies, noting: “Unequal access and cultural differences affecting uptake could create large differences in the relative incidence of a given condition by region, ethnic group, or socioeconomic status. Genetic disease, once a universal common denominator, could instead become an artifact of class, geographic location, and culture.” A dangerous consequence of such inequality could be that “reduced incidence and reduced sense of shared risk could affect the resources available to individuals and families dealing with genetic conditions.”
Having touched on each of these issues, the group then outlined its consensus positions:
1. At this time, given the nature and number of unanswered scientific, ethical, and policy questions, it is inappropriate to perform germline gene editing that culminates in human pregnancy.
It was noted that there is not yet a high quality evidence base to support the use of germline genome editing, with unknown risk of health consequences and ethical issues still to be explored and resolved by society.
The group observed that two major categories of safety concerns are (i) the effect of unwanted or off-target mutations, and (ii) the potential unintended effects of the desired on-target base changes (edits) being made. It noted that it is reasonable to presume that any human genome-editing therapeutic application will require stringent monitoring of off-target mutation rates, but there remains no consensus on which methods would be optimal for this, or what a desirable maximum off-target mutation rate would be when these techniques are translated clinically. The working-group thus outlined its views on the minimum necessary developments that would be required (at least from a safety perspective) before germline genome editing could be used clinically:
- definitions of broadly acceptable methodologies and minimum standards for measuring off-target mutagenesis;
- consensus regarding the likely impact of, and maximum acceptable thresholds for, off-target mutations; and
- consensus regarding the types of acceptable genome edits with regard to their potential for unintended consequences.
2. Currently, there is no reason to prohibit in vitro germline genome editing on human embryos and gametes, with appropriate oversight and consent from donors, to facilitate research on the possible future clinical applications of gene editing. There should be no prohibition on making public funds available to support this research.
The group agreed that conducting basic scientific [techniques?] involving editing of human embryos and gametes can be performed ethically via compliance with applicable laws and policies, and that any study involving in vitro genome editing on human embryos and gametes should be conducted under rigorous and independent governance mechanisms, including approval by ethics review boards and meeting any other policy or regulatory requirements. Public funding for such research was seen as important in ensuring that such research is not driven overseas or underground, where it would be subject to less regulation, oversight and transparency.
3. Future clinical application of human germline genome editing should not proceed unless, at a minimum, there is (a) a compelling medical rationale, (b) an evidence base that supports its clinical use, (c) an ethical justification, and (d) a transparent public process to solicit and incorporate stakeholder input.
Even if the technical data from preclinical research reaches a stage where it supports clinical translation of human germline genome editing, the working group stresses that “many more things need to happen before translational research in human germline genome editing is considered”. The criteria identified by the group in this position cut across medical, ethical, economic and public participation issues and represent the setting of an appropriately high and comprehensive standard to be met before human germline genome editing may be applied clinically. The group acknowledges the challenges of public engagement with such technical subject matter but encourages new approaches to public engagement and engagement of broader stakeholder groups in the public discussion.
The ethical implications of altering the human germline has been the subject of intense discussion in recent years, with calls for such work to be put on hold until the process of genome editing is better understood. ASHG supports somatic genome editing and preclinical (in vitro human and animal) germline genome research but feels strongly that it is premature to consider human germline genome editing in any translational manner at this time.
The working group concludes that “Many scientific, medical, and ethical questions remain around the potential for human germline genome editing. ASHG supports somatic genome editing and preclinical (in vitro human and animal) germline genome research but feels strongly that it is premature to consider human germline genome editing in any translational manner at this time. We encourage ethical and social consideration in tandem with basic science research in the upcoming years”.
This appears a reasonable position largely in line with the recommendations from the major national and international groups surveyed by the working group. It balances the need to encourage further basic research and validation with strong awareness of the ethical and societal implications of human germline genome editing, setting a high bar before such technology should be translated to the clinic. No doubt, however, the debate will continue, particularly in respect of public funding for such work. Whether the US will maintain their stance against public funding, in the face of international competition, and potential loss of talent and investment, remains to be seen.
For more information about the science of CRISPR, its wide range of applications in life sciences and beyond, and latest developments in the field, please see Allen & Overy’s dedicated CRISPR microsite.