Research on the ELSI and impacts of human gene editing should be conducted in tandem with the basic scientific research, as well as with any implementations of gene editing in the clinic. Appropriate resources and priority should be granted to support and promote ELSI research; it should be performed unabated, in a meaningful way and by individuals from a diverse range of disciplines (Table 2).

Table 2 Example of questions needed to be addressed for the ethical, legal, and social issues research (ELSI) of gene editing Full size table

Ongoing research, reflection and dialogue should address all ELSIFootnote 3salient to gene editing. With respect to gene editing in humans, both somatic and germ line/heritable embryonic gene editing contexts should be addressed. As stated above, we should also study the ELSI of gene editing in non-human and non experimental/model organisms, including issues surrounding the potential (legal and logistical related to implementation) confusions surrounding the use of the terms genetically modified organisms vs. the term gene-edited organisms.

Somatic gene editing

Although somatic gene editing is not free from ethical, legal and social implications—it is, in many respects, similar to more traditional 'gene therapy' approaches in humans—it has been suggested that in many cases, the use of somatic gene editing does not challenge existing ethical, legal and social frameworks as much as heritable gene editing. However, as with any new experimental therapeutic, the unknowns still outweigh what is known and issues of risk assessment and safety, risk/benefit calculation, patient monitoring (potentially for long periods), reimbursement, equity in access to new therapies and the potential for the unjustified draining of resources from more pressing (albeit less novel) therapies, particular protection for vulnerable populations (e.g., fetuses, children (lacking competencies)), and informed consent remain important to study further [26].

Furthermore, as with any new (disruptive) technology or application, there often remains a gap to be filled between the setting of abstract principles or guidelines and how to apply these in practice. Indeed, important questions and uncertainties surrounding somatic gene editing both in research and in the clinic remain, including, but not limited to: do the established (national and international) legal and regulatory frameworks (e.g., Regulation (EC) no. 1394/2007 on advanced therapy medicinal products) need further shaping/revisions to appropriately address somatic gene editing (including not just issues with the products per se but also for issues related to potential health tourism)? And if so, how would this best be accomplished? Do present clinical trial principles and protocols suffice? How exactly will trials in somatic gene editing be conducted and evaluated? Do we need particular protection or status for patients in such trials? What procedures will be instilled for patients receiving such treatments (e.g., consent, genetic counselling, follow-up monitoring)? Furthermore, to what extent will commercial companies be able to, or be allowed to offer, potentially upon consumer request, treatments based on techniques where so much uncertainty regarding harms remains? Importantly, which health-care professionals will be involved in the provision of somatic gene therapy and the care of patients who undergo such treatments? Who will decide on roles and responsibilities in this novel context? And, based on what criteria will the eligible diseases/populations to be treated be chosen? Indeed, these questions can also all be applied to the context of heritable gene editing, which is discussed below.

Germ line/heritable gene editing

With respect to germ line or heritable gene editing in humans, the ELSI are more challenging than for somatic gene editing, yet they are not all new per se either. Some of these previously discussed concerns include, but are not limited to: issues addressing sanctity of human life, and respect for human dignity, the moral status of the human embryo, individual autonomy, respect and protection for vulnerable persons, respect for cultural and biological diversity and pluralism, disability rights, protection of future generations, equitable access to new technologies and health care, the potential reduction of human genetic variation, stakeholder roles and responsibilities in decision making, as well as how to conduct 'globally responsible' science [16, 2, 11, 18]. Discussions and debates over some of these topics have been held numerous times in the last three decades, especially within the context of in vitro fertilization, transgenic animals, cloning, pre-implantation genetic diagnosis (PGD), research with stem cells and induced pluripotent stem cells, as well as related to the large scope of discussion around 'enhancement' [13]. Although it is important to identify and reflect on more general ELSI linked with heritable gene editing and these different contexts, it is also vital to reflect on the ELSI that may be (more) specific to this novel approach. For example, would the fact that for the first time a human (scientist or clinician) would be directly editing the nuclear DNA of another human in a heritable way cause some form of segregation of types of humans? Creators and the created? [27] Clearly, we need time for additional reflection and discussion on such topics. Distinguishing the ELSI between different yet related contexts will allow for a deeper understanding of the issues and the rationale behind their (un)acceptability by different stakeholders.

A major contextual difference in the current discussions regarding germ line/heritable gene editing is that we have never been so close to having the technology to perform it in humans in a potentially safe and effective manner. Hence, as we move closer to this technical possibility and as we work out the scientific issues of efficiency and safety, the discussions orient themselves increasingly towards the ELSI regarding whether or not we want to even use heritable gene editing in a laboratory or clinical setting, and if so, how we want it to be used, by whom and based on which criteria? This includes, but is not limited to the following questions: should gene editing of human germ line cells, gametes and embryos be allowed in basic research—for the further understanding of human biology (e.g., human development) and without the intention of being used for creating modified human life? Some jurisdictions, such as the UK, have already answered this question, and are allowing this technique in the research setting in human cells in vitro (they will not be placed in a human body, the research will only involve studying the human embryos outside of the body) whereby researchers need to apply for permission to conduct such research. Some believe that allowing this will inevitably lead to the technology being used in the clinic (the so-called 'slippery slope' argument). This, then, brings us to the question at the centre of the debate: should gene editing of germ line cells, gametes or embryos or any other cell that results in a heritable alteration be allowed in humans in a clinical setting? Germane to this issue is another vital question: what, if any, principles or reasoning would justify the use of hereditary gene editing in humans in a clinical context given the current ban on such techniques in many jurisdictions? The new EU clinical trial Regulation (536/2014 Art 90 al.2.) does not allow germ line modification in humans. Should there be leeway for reconsidering this ban in the future in view of the possible benefits of therapeutic germ line gene editing? Should we first understand the risks and benefits of somatic gene editing before even seriously considering heritable gene editing? If we consider that it could be used in some situations, should we only consider using germ line gene editing in the clinic if there are absolutely no other alternatives? Should already established and potentially saferFootnote 4 reproductive alternatives, like PGD, be the approaches of choice before even considering germ line gene editing? If we do entertain its use, what, if any criteria, will be safe enough according to different stakeholders (scientists, ethicists, clinicians, policy makers, patients, general public) for it to be legitimate to consider using gene editing for reproductive use? Who will set this safety threshold and based on what risk/benefit calculations? Furthermore, if ever allowed, should heritable human gene editing be permitted only for specific medical purposes with a particular high chance of developing a disease (e.g., only when parents have a-near-100% risk of having a child affected with a serious disorder), and if so, would it matter if the risk is not 100%, but (much) lower? In addition, how can we, or should we define/demarcate medical reasons from enhancement? And, as was posed above for the use in somatic cells, for what medical conditions will gene editing be considered appropriate for use? What will the criteria be and who will decide?

Taking a step back and looking at the issues from a more general perspective, such ELSI research and reflection will need to address, among others, questions that fall under the following themes:

the balance of risks and benefits for individual patients and also for the larger community and ecosystem as a whole;

the ethical, governance and legislative frameworks;

the motivations and interests 'pushing' gene editing to be used;

the roles and responsibilities of different stakeholders in ensuring the ethically acceptable use of gene editing, including making sure that every stakeholder voice is heard;

the commercial presence, influence, and impact on (the use of) gene editing;

the rationale behind the allocation of resources for health care and research and if and which kind of shift might be expected with the new technologies on the rise.

Additional overarching issues relating to ELSI include the need to take a historical perspective and consider previous attempts to deal with genetic technologies and what or how we can learn from these; the need to consider how group actors could or should accept a shared global responsibility when it comes to the governance of gene editing; the potential eugenic tendencies related to new technologies used to eliminate disease phenotypes; the responsibility of current society for future generations; the way different stakeholders may perceive and desire to eliminate (genetic) risk and/or uncertainty by using new technologies such as gene editing; and the potential role(s) different stakeholders, including 'experts', may inadvertently play in propagating a false sense of control over human health.

Although the human context is where much of the attention currently resides, and is indeed, the focus of this article, as mentioned above, we also stress that many concerns and ELSI also stem from the use of gene editing in non-human organisms (plants, insects and microorganisms), the study of which, could inform the human context. More importantly, given that the use of gene editing in these organisms is currently taking place in laboratories and, if released, some of these gene-edited organisms could have a large impact on the environment and society [2], the ELSI of gene editing in non-human organisms should also be seriously addressed. In this respect, the current debates over definitions and whether plants and non-human animals in which gene editing is performed are considered (legally) genetically modified organisms (GMOs) are particularly important to consider; indeed, this legal stance may be a misleading way to describe the scientific differences in practice. Moreover, the manipulation of definitions may also be used to circumvent the negative press and opinions surrounding GMOs in Europe. Last, but not least, the use of gene editing for the creation of biologic weapons is a possibility that must be discussed and adequately managed [2].

In order to ensure that the appropriate ELSI research is conducted to answer these myriad questions, ELSI researchers must ensure adequate understanding of scientific facts and possibilities of gene editing, ensure appropriate use of robust methods [29] to answer specific ELSI questions, as well as learn from previous research on related themes such as (traditional) gene therapy, reproductive technologies, and GMOs. Furthermore, funding will have to be prioritized for ELSI research. National and European funding agencies should ensure that ELSI funding is given in certain proportion to how much gene editing research is being conducted in the laboratory and (pre) clinical domain. In practice, this will mean ensuring that there are adequate review panels for stand-alone ELSI grants, which do not usually fall within any one traditional academic field (e.g., philosophy, law or social sciences). The requirement of including ELSI work packages within science grants may also be useful if such work packages are conducted by ELSI experts (and this is verified by the funding agencies), that they are given enough budget to conduct research and not only offer services, and that the ELSI work package is not co-opted by the science agenda. Spending money on ELSI research has already allowed for the information to be used in more applied ways. Among others, ELSI research has contributed to helping individual researchers understand what kind of research they are (not) allowed to do in certain countries or regions; helped to design appropriate consent forms for research and clinic; and has helped inform policy decisions.

As ELSI are identified, studied and discussed, it will be of utmost importance to communicate these with as many publics as relevant and possible in a clear and comprehensive way so that the largest number of different stakeholders can understand and engage in a discussion about these issues. With respect to engaging non-academic and non-expert audiences in meaningful dialogue, the challenges are greater. Yet, as this is a vital element of conducting science and preparing clinical applications in a responsible manner and stretches beyond the academic focus of ELSI we propose to distinguish a third domain dedicated to such stakeholder engagement, education and dialogue (SEED) described below.