Will gene editing become a part of everyday medicine?
Gene editing holds the key to preventing or treating debilitating genetic diseases, giving hope to millions of people around the world. Yet the same technology could unlock the path to designing our future children, enhancing their genome by selecting desirable traits such as height, eye color, and intelligence.
While gene editing has been used in laboratory experiments on individual cells and in animal studies for decades, 2015 saw the first report of modified human embryos.
The number of published studies now stands at eight, with the latest research having investigated how a certain gene affects development in the early embryo and how to fix a genetic defect that causes a blood disorder.
The fact that gene editing is possible in human embryos has opened a Pandora's box of ethical issues.
So, who is in favor of gene editing? Do geneticists feel differently about this issue? And are we likely to see the technology in mainstream medicine any time soon?
What is gene editing?
Gene editing is the modification of DNA sequences in living cells. What that means in reality is that researchers can either add mutations or substitute genes in cells or organisms.
While this concept is not new, a real breakthrough came 5 years ago when several scientists saw the potential of a system called CRISPR/Cas9 to edit the human genome.
CRISPR/Cas9 allows us to target specific locations in the genome with much more precision than previous techniques. This process allows a faulty gene to be replaced with a non-faulty copy, making this technology attractive to those looking to cure genetic diseases.
The technology is not foolproof, however. Scientists have been modifying genes for decades, but there are always trade-offs. We have yet to develop a technique that works 100 percent and doesn't lead to unwanted and uncontrollable mutations in other locations in the genome.
In a laboratory experiment, these so-called off-target effects are not the end of the world. But when it comes to gene editing in humans, this is a major stumbling block.
Here, the ethical debate around gene editing really gets off the ground.
When gene editing is used in embryos — or earlier, on the sperm or egg of carriers of genetic mutations — it is called germline gene editing. The big issue here is that it affects both the individual receiving the treatment and their future children.
This is a potential game-changer as it implies that we may be able to change the genetic makeup of entire generations on a permanent basis.
Who is in favor of gene editing?
Dietram Scheufele — a professor of science communication at the University of Wisconsin-Madison — and colleagues surveyed 1,600 members of the general public about their attitudes toward gene editing. The results revealed that 65 percent of respondents thought that germline editing was acceptable for therapeutic purposes.
When it came to enhancement, only 26 percent said that it was acceptable and 51 percent said that it was unacceptable. Interestingly, attitudes were linked to religious beliefs and the person's level of knowledge of gene editing.
"Among those reporting low religious guidance," explains Prof. Scheufele, "a large majority (75 percent) express at least some support for treatment applications, and a substantial proportion (45 percent) do so for enhancement applications."
He adds, "By contrast, for those reporting a relatively high level of religious guidance in their daily lives, corresponding levels of support are markedly lower (50 percent express support for treatment; 28 percent express support for enhancement)."
Among individuals with high levels of technical understanding of the process of gene editing, 76 percent showed at least some support of therapeutic gene editing, while 41 percent showed support for enhancement.
But how do the views of the general public align with those of genetics professionals? Well, Alyssa Armsby and professor of genetics Kelly E. Ormond — both of whom are from Stanford University in California — surveyed 500 members of 10 genetics societies across the globe to find out.
What do professionals think?
Armsby says that "there is a need for an ongoing international conversation about genome editing, but very little data on how people trained in genetics view the technology. As the ones who do the research and work with patients and families, they're an important group of stakeholders."
In total, 31.9 percent of respondents were in favor of research into germline editing using viable embryos. This sentiment was more particularly pronounced in respondents under the age of 40, those with fewer than 10 years experience, and those who classed themselves as less religious.
The survey results also revealed that 77.8 percent of respondents supported the hypothetical use of germline gene editing for therapeutic purposes. For conditions arising during childhood or adolescence, 73.5 percent were in favor of using the technology, while 78.2 percent said that they supported germline editing in cases where a disease would be fatal in childhood.
On the subject of using gene editing for the purpose of enhancement, just 8.6 percent of genetics professionals spoke out in favor.
"I was most surprised, personally," Prof. Ormond told Medical News Today, "by the fact that nearly [a third] of our study respondents were supportive of starting clinical research on germline genome editing already (doing the research and attempting a pregnancy without intent to move forward to a liveborn baby)."
This finding is in stark contrast to a policy statement that the ASHG published earlier this year, she added.
Professional organizations urge caution
According to the statement — of which Prof. Ormand is one of the lead authors — germline gene editing throws up a list of ethical issues that need to be considered.
The possibility of introducing unwanted mutations or DNA damage is a definite risk, and unwanted side effects cannot be predicted or controlled at the moment.
The authors further explain:
"Eugenics refers to both the selection of positive traits (positive eugenics) and the removal of diseases or traits viewed negatively (negative eugenics). Eugenics in either form is concerning because it could be used to reinforce prejudice and narrow definitions of normalcy in our societies."
"This is particularly true when there is the potential for 'enhancement' that goes beyond the treatment of medical disorders," they add.
While prenatal testing already allows parents to choose to abort fetuses carrying certain disease traits in many places across the globe, gene editing could create an expectation that parents should actively select the best traits for their children.
The authors take it even further by speculating how this may affect society as a whole. "Unequal access and cultural differences affecting uptake," they say, "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 artefact of class, geographic location, and culture," they caution.
Therefore, the ASHG conclude that at present, it is unethical to perform germline gene editing that would lead to the birth of an individual. But research into the safety and efficacy of gene editing techniques, as well as into the effects of gene editing, should continue, providing such research adheres to local laws and policies.
In Europe, this is echoed by a panel of experts who urge the formation of a European Steering Committee to "assess the potential benefits and drawbacks of genome editing."
They stress the need "to be proactive to prevent this technology from being hijacked by those with extremist views and to avoid misleading public expectation with overinflated promises."
But is the public's perception really so different from that of researchers on the frontline of scientific discovery?
Working together to safeguard the future
Prof. Ormond told MNT that "a lot of things are similar — both groups feel that some forms of gene editing are acceptable, and they seem to differentiate based on treating medical conditions as compared to treatments that would be 'enhancements,' as well as based on medical severity."
"I do think there are some gaps [...]," she continued, "but clearly knowledge and levels of religiosity impact the public's views. We need to educate both professionals and the public so that they have a realistic sense of what gene editing can and cannot do. Measuring attitudes is difficult to do when people don't understand a technology."
While advances such as CRISPR/Cas9 may have brought the possibility of gene editing one step closer, many diseases and traits are underpinned by complex genetic interactions. Even a seemingly simple trait such as eye color is governed by a collection of different genes.
To decide what role gene editing will play in our future, scientific and medical professionals must work hand-in-hand with members of the general public. As the authors of the ASHG position statement conclude:
"Ultimately, these debates and engagements will inform the frameworks to enable ethical uses of the technology while prohibiting unethical ones."