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CRISPR: Should we allow human genome editing?

Figure 1 Editing the genome[1]

Hello and welcome to my next blog post.

In this post I shall be discussing the opinions surrounding genome editing technology of CRISPR/Cas9 (figure 1). The National Academies of Science has declared genome editing a better name than gene editing as sometimes the editing may be in the parts of the genome that regulate rather than code for genes. There are arguments for and against CRISPR but first some background…

How does it work?

Figure 2 CRISPR publications[4]

CRISPR stands for Clustered Regularly Interspaced Palindromic Repeats and is a way of making targeted changes to the genome. It is being used more and more (figure 2) and the video below[3] gives a short overview.


What stage are we at?

CRISPR works really well compared to the old methods of TALENs and zinc finger nucleases[5]. In December 2015 a summit on human gene-editing came to this conclusion (figure 3):

CRISPR committee
Figure 3 CRISPR summit conclusion[6]
Since then the UK has become the first country to formally approve CRISPR[7]. Dr Niakan at the Crick Institute has been licensed by the Human Fertilisation and Embryology Authority but edited embryos cannot be implanted. They are going to be looking at what genes are needed for a healthy baby to develop to better understand why miscarriages occur[5].

It has been widely used in crops including wheat and commercialisation is coming ever closer[5]. As this happens we must think about unintended consequences. For example, regulation may not be equal in all countries and some may take advantage of this to begin human trials before others. The National Academies of Science reported in February 2017 that trials may start after much more research[8] but also followed this thought with the example of genetic tourism. If it can be done then it may not be long before it is done in less strictly controlled countries. The US has a 2016 law that prevents the use of research with edited human embryos with a heritable change[2]. It is likely that there will be a lot of money in it for those that are the first to successfully make life changing differences by removing genetic defects so this is a serious issue.



Many scientists are strongly for CRISPR because it will make a huge difference to research. The main benefits of CRISPR are:

It is fast, it is precise and it is inexpensive so nearly anyone can do it.

Figure 4 The editing of the genome[1]
Specific areas of the genome (figure 4) (and multiple ones) can be targeted and it takes months rather than years as previous gene editing techniques did[4]. The CRISPR/Cas9 system does not use any foreign DNA so there are no transgenes involved and there are fewer unintended mutants[5]. Further possible uses for CRISPR include:

  • Xenotransplantation (transplants from non-humans e.g. pigs) as they could be edited to prevent rejection.
  • Improved models for human disease could speed up drug development
  • Novel ways to fight disease such as removing breeding in mosquitoes that spread malaria and Zika virus[4]

Editas Medicine plans to use it to treat Leber congenital amaurosis (LCA10), a rare eye disease which may lead to blindness. CRISPR also holds promise for those undergoing cancer treatment. Several groups hope to use it to boost the function of T-cells so that the body is better at recognising and removing cancerous cells[1].

These examples show only some of the uses for CRISPR. I believe that CRISPR has incredible potential. The opportunities offered by it are revolutionising science and allowing scientists to do experiments that would have been impossible 10 years ago. If regulated and controlled correctly it will be able to make some truly amazing changes to people’s lives. So why are people against it?


Against CRISPR

The problem with genome editing is that the possibilities are almost endless which raises many questions about safety. One of the biggest fears that people voice about it is that it could be used for enhancement e.g. designer humans. The ability to choose the traits for your child would most likely be centred around the rich which would lead to greater inequality than the world already exists with. People worry that we could see a return to the eugenics ideas of the 1940s[9]. The National Academies of Science published a report which concluded that editing “beyond levels considered typical of adequate health” should not be permitted[2].

There is a lot of opposition and public opinion will be a massive hurdle. There are worries that it will cause cancer and other negative health impacts through inaccurate editing or genetic complications. Doctors can already screen for many diseases in pre-implantation screening so some argue CRISPR is unecessary[9]. There are already protests over GM food so protests over editing in humans is likely to be much greater[10].

Naturally, the possibility of making changes to the germline leads to controversy with CRISPR. It is hard to know what making these changes would do in the future and as with any new technologies what the consequences might be. I can see why people are against these changes as you are making changes to someone in the future who has had no say in the matter which is unethical. More research is needed before editing to the germline in humans should even be considered for clinical trials.


Patent debate

Figure 5 Feng Zhang and Jennifer Doudna[12]
The commercial potential is huge and there has been a patent argument for the CRISPR system and who invented it as a gene editing technique first. On one side was Professor Doudna’s team at the University of California (who first did it in test tubes) and on the other is Feng Zhang team from the Broad Institute (who first did it in human cells)[4] (figure 5). A court ruled in February 2017 in favour of the Broad Institute however it is thought that this will only affect who gets the financial rewards and will not stop scientists from using the technology[10].

You can read more about how this debate came about here and about the court result here.

In conclusion, CRISPR/Cas9 is making and will continue to make it possible to speed up investigations into many genetic defects that cause all sorts of disease and which would previously have taken much longer to discover. As with any genetic engineering, there was always going to be controversy and ethical questions. I think that as long as it is regulated carefully and checked for safety, it can be used but only to improve life and not for aesthetic reasons. A further international summit to discuss genome editing is being organised in China for later this year[8].



[1] McFarling U.L, 2017. Stat.

[2] Begley S., 2017. No red line against CRISPR’ing early embryos, experts rule. Stats News.

[3] Video courtesy of Sputnik Animation, the Broad Institute of MIT and Harvard, Justin Knight and pond5

[4] Groenholm A., 2016. On Genome Editing and Patent Battles – Exploring the CRISPR World. Med Engine.

[5] Gallager J., 2016. Scientists get ‘gene editing’ go-ahead. BBC News Health.

[6] National Academy News, 2015. On human gene-editing: International summit statement. National Academies of Sciences, Engineering and Medicine.

[7] Walsh F., 2016. Gene editing technique could transform future. BBC News Health.

[8] Kaiser J., 2017. U.S. panel gives yellow light to human embryo editing. Science News.

[9] Lewis T., 2015. There are really good reasons why we should — and shouldn’t — genetically engineer human embryos. UK Business Insider.


[11] Cohen J., 2017. Round one of CRISPR patent legal battle goes to the Broad Institute. Science News. DOI: 10.1126/science.aal0770.

[12] Begley S., 2017. Stat.

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