CRISPR gene editing questions answered by leading scientist

Alex Hughes speaks to Edze Westra, a researcher at Exeter Penryn Campus about the use of CRISPR gene editing and its benefits in treatment and design. (Questions by Alex Hughes and Jordan Healey)


CRISPR gene editing has become a topic of much controversy and discussion in recent years. The experimental technology could allow us to manipulate DNA to change genetics and even cure illnesses such as cancer or create specifically designed children.

With such a powerful technology, many scientists are arguing that this form of technology should be treated with extreme ethical consideration and that the line between curing diseases and designing heightened humans is only a small one.

With this issue in mind, I spoke to Edze Westra, a senior research fellow at Exeter Penryn Campus and specialist in gene editing, about CRISPR, its benefits and its risks.

Edze Westra

How does the CRISPR-CAS 9 system work in order to treat diseases like cancer?

CRISPR-Cas9 allows for precision genome editing. One can re-program immune cells to recognise cancers, and put these immune cells back into the patient to help cure the disease.

(see this article:)

How does the body react to having genes altered? Are there any
dangerous short term or long term side effects? Since the technology
is relatively new, how can we be sure it’s safe?

The main purpose of editing genes would be to invoke a strong reaction. For example, repair of a gene that carries a mutation that disrupts its ability to carry out a key function  – say production of a hormone – would deliver a strong effect on the patient. One of the risks is that other genetic loci are affected. This so-called off-target activity of CRISPR-Cas9 has been the focus of a lot of research over the past years, and the rates of off-target events have been greatly reduced. That said, there is always a risk, which one needs to carefully weigh against the predicted benefits of the treatment. In the future, as genome sequencing becomes increasingly cheap and easy, one could theoretically check whether any off-target effects occurred.

We have already seen human trials for gene editing take place in
China, however, the ethical questions raised about ‘designer babies’
(and other potential misuses of the tech) have led to concern amongst
many people. What can the scientific community do to ensure that this
technology isn’t exploited?

A scientific panel chaired by Prof Hynes (MIT) has recommended against using the technology for enhancement therapy. Having these regulations in place is key to limit abuse. It is important to note that a lot of characteristics will be incredibly hard to edit into genomes, as we often do not know the genetic basis. Take for example intelligence, which is a complex trait that involves many genes and interactions between them of which we still know very little.  Altering such a complex trait would be far beyond what is currently possible. My personal view is therefore that the expected benefits of this technology greatly outweigh the potential downsides, particularly as proper regulations to avoid such abuse are already in place, and technical knowledge to manipulate traits of interests is lacking.

Besides treating cancer CRISPR has many other potential uses such as
modifying plants produced for food. Can these also be achieved in the
next 20 years despite political and media objections? 

I would imagine that this technology will be commonly used for editing plant genomes, simply because (in my view) this technique would allow far more control over the traits of crops, which makes it easier, safer and cheaper compared to existing techniques. Note that classical plant breeding also aims to change the DNA in order to generate crops with particular traits of interest. Sometimes this process is aided by the use of radiation or chemicals. To me, using CRISPR-Cas9 seems to be a far safer and more desirable alternative. However, the public opinion will play an important role in the direction this technology will take, and it will therefore be key to have this debate now. How this needs to be regulated depends, in my view on whether foreign genes are introduced or whether existing genes are edited.

Can the use of CRISPR tech be funded sufficiently in order to achieve
these ambitious end goals?

I am confident enough funding will be flowing into research on these applied aspects of CRISPR-Cas9, which will help to deliver life-changing technologies.

Do you feel that the positives of CRISPR outweigh the worries that
people have around it?

Yes; CRISPR-Cas9 technology has the capacity to limit, suppress or even eliminate a wide range of diseases. Recent work has shown how CRISPR-Cas9 systems can be used to prevent malaria transmission, which affects many millions of people. Other research has shown how CRISPR-Cas9 can contribute to curing cancers, edit genes that cause genetic diseases, such as Huntington’s disease, or edit genes in human cells in order to resist infection by HIV. On top of that CRISPR-Cas9 can be used to improve crops, and replace expensive breeding programmes. Others would like to use CRISPR-Cas9 to improve resilience of endangered species, or even to revive species that went extinct. This is a truly revolutionary technology, and the downsides would need to be enormous if they were to outweigh the benefits. In my view, the benefits are far greater.

realistically, how far into the future is this treatment?

It is of course hard to estimate how quickly this technology will start to be used in clinics and elsewhere, and it depends on the precise application how long this will take. Some crops have already been edited with CRISPR-Cas9 (see, and trials for using CRISPR-Cas9 to treat cancer are in progress (see link above and links therein). I think many of the benefits of CRISPR-Cas9 will already start to crystallise over the next decade, but for some applications, the time span will be longer.

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