Alexander Marshall discusses the benefits and concerns of genetically modifying embryo DNA to help families plagued by deadly diseases
The 21st century may, for the first time, see a generation of genetically modified human beings, but are we prepared? Earlier this year, Dr Shoukhrat Mitalipov, from The Oregon Health and Science University, made headlines as the first US researcher to alter the DNA of a human embryo to remove a disease-causing gene.
The gene, known as MYBPC3, causes the heart tissue to thicken, leading to a condition linked with sudden death in young adults. Dr Mitalipov corrected the gene using the DNA editing technique CRISPR. While he made worldwide headlines, many would fail to realise he was not the first to accomplish such a feat. Instead, he has merely achieved a far higher success rate than his Chinese counterparts.
While Mitalipov’s research has achieved success that others have not, many researchers across the globe are striving to achieve advancements in genetically modified embryos. Although these efforts aim to eradicate disease, and offer a new lease of life in predisposed individuals, it is probably naïve to assume that these large-scale efforts to develop techniques for editing embryos are purely for scientific research, or that the tight regulations some countries have in place will be globally enforced. So, what could this mean for research and, ultimately, society?
Firstly, let us look at the effect on research. Currently, embryos may only be used for up to 14 days, long before the development of tissues and the nervous system. However, there is a push by some to increase this time frame to allow researchers to better understand the processes which occur in early embryo development, furthering regenerative medicine and cancer research. Naturally, many are wary of raising this limit, yet the developing heart only begins to beat at week 5, and abortions can occur in the UK up to week 24. So, where do we draw the line? Despite the great therapeutic potential of CRISPR, the long-term health of a genetically modified human embryo is unknown.
Even if the science of gene modification is viable, what benefits these treatments could really provide is unclear. Many argue that it could change lives. While true, often you would need to be aware of the risk before conception, and many conditions are far more complex than one faulty gene. As DNA changes using CRISPR would require validation before embryos are implanted, would we also be introducing more complications than necessary? Instead, diseases that are almost certainly caused by one gene could be detected with better pre-implantation checks, and would alleviate the need for genetic modification. Pre-implantation screening checks DNA before implanting IVF-derived embryos, to ensure only healthy embryos are chosen, and is already in use for various conditions.
The considerations discussed so far have not even taken into account the safety of CRISPR itself. Many have reported that unintended alterations in DNA are rare with CRISPR. However, there are some who suggest a much higher occurance rate. CRISPR has only been in extensive use since 2013, and is still an incredibly new tool to the scientific community, so caution has to be taken when translating this technology to humans.
Lastly, while there are concerns for the safety of the embryo itself, some feel the greatest risk is the effect of genetic modification on society. On a population scale, it is important to understand that genetic diversity makes a stronger species, as it allows a group to adapt to an altering environment. Even mutations which can be detrimental in ordinary life can be beneficial in some extreme situations. A prime example of this is sickle cell anaemia, where one copy of the mutant gene confers a protection from malaria in African populations, whereas two copies lead to severe health complications. Although the genetic variation within a population is also reduced by using pre-implantation screening, the alternative, to allow people to suffer with terrible diseases, is inconceivable.
Even though genetically modified embryos may be highly desirable, the long-term impact of this path may lead us into a dark place and, while it may sound like a dystopian future, could ultimately have a detrimental impact on future generations. Government bodies could try to regulate genetic modification, though individuals who desire gene therapy will find ways to undertake this: privileged individuals have a history of circumventing the law, allowing them to request traits or physical attributes to give their child an extra biological advantage over others.
Overall, while an incredible feat of science has been achieved, there are still concerns regarding the long-term consequences of exercising such power. Altering embryonic DNA, and therefore the DNA of future generations, is game-changing, and is a conversation we should all be involved in.
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