In 2012 the successful development of the gene editing method called CRISPR-Cas9 changed the scientific community. Since its invention, not a day goes by without a new “breakthrough” using this technology. Scientist and patients became frustrated over the lack of progress in finding new cures for genetically inherited diseases. Earlier methods were less precise, very expensive and took a long period to generate some results; time that many patients do not have. Now with the appearance of CRISPR-Cas9 method gene editing can be accomplished much easier and results available within days, not months or years.
Many genetic diseases are caused by mutations in our genes. Our genes are made of the building blocks called amino acids Adenine (A), Cytosine (C), Guanine (G) and Tyrosine (T). The whole book we call our genome, the totality of our genes, is written with just four letters, A, C, G, and T. Our DNA, the double-stranded helix that hosts our genes, contains about 6 billion of these amino acids, arranged in a very specific order. Proteins that our body needs on a daily base are encoded by a very specific linear arrangement and combination of the amino acids. Let’s hear it explained by the co-inventor of CRISPR/Cas9, Dr. Jennifer Douda at University of California, Berkeley:
Now you know what CRISPR/Cas9 can do. It is a very powerful tool.
Recently, the news reported about the use of CRISPR/Cas9 by Dr. He Jianku in China. Dr. He claims that using this technique, he removed the gene responsible for HIV infection in humans and made the two babies immune to HIV. The editing was done when the babies were embryos.
The news of Dr. He’s work was the nightmare Dr. Douda: “I’ve mentally prepared myself for the day when I open my inbox or answer my phone and realize that somebody’s going to be announcing the first crispr baby.”
First of all, this kind of gene editing is prohibited in the US, Europe, and many other countries.
Second, CRISPR technology is not as straightforward as one might think. Yes, it is a great tool, but it also has some problems. While in most cases it can correct the mutations, CRISPR can also introduce unwanted mutations in other genes, the so-called off-target effects.
There were previous gene editing experiments. One of them was by , Dr. Huang from China who edited the gene that causes thalassemia. Dr. Mitalipov at Oregon Health Science University modified the gene that causes hypertrophic cardiomyopathy. While these two scientist edited an existing gene, Dr. He completely deleted an existing gene in all cells of the babies’ body. Moreover, Dr. He’s deletion was incomplete, and only one of the embryos had “complete” immunity against HIV, while the other baby is only 50% immune and still can catch HIV.
The gene deleted by Dr. He is called CCR5. Now, while the deletion of this gene might make at least one of the babies completely immune against certain types of HIV, other versions of the HIV virus, and there are several, can still infect these patients through another protein called CXCR4. The deletion of CCR5 might also introduce other infection potentials, making these patients more susceptible to West Nile Virus, influenza, and Japanese encephalitis. These are the facts we know so far. However, the scary part is what we do not know, and it might be a lot.
The babies born with Dr. He’s gene deletion will have to live with the lifelong worry about developing other, so far unknown complications due to the inherent off-target-effects of CRISPR. Also, they might still be susceptible to HIV infection through so far unknown mechanism.
The babies parents were HIV positive. Dr. He justifies his illegal editing with his desire to give the babies of HIV positive parents a healthy future without HIV infection. It might be an honorable goal if there were no other methods of preventing the infection of the babies by a HIV positive mom during birth. Every day, healthy babies are born to HIV positive moms without getting infected. Hence, Dr. He’s reckless experiment was unnecessary.
In 2015, at an international summit, scientist from all over the world, including China, agreed that gene editing with CRISPR/Cas9 requires first a conses in the society before using it to customize humans. We as a society have to answer the question about WHY and WHEN we should use CRISPR technology for gene editing. We must discuss all the potential benefits and risks of this methods and be aware of that we don’t know all the off-target-effects of it, before we arrive at a societal consent about the application of CRISPR. In doing so, we must educate ourselves about the genetic origins of different diseases. Diseases such as Huntington’s Disease caused by mutations in a single gene might be a good target for CRISPR. However, many other inherited diseases, such as Diabetes, Alzheimers disease and many forms of cancers are caused by hundreds or thousands of mutation, which all need to be CRISPR’ed, with greatly increasing amount of off-target-effects.
The main controversy about CRISPR is not about medical treatment options using this method but about designing humans by manipulating their genes. The dystopian vision includes ready-to-order designed humans , gene manipulated individuals to be born as soldiers immune to fear and pain and edited traits such as improved intelligence or endurance, to name a few.
The society is rightfully afraid of humans created a-la-carte in unscrupulous laboratories or companies, with little or no oversight.
Moreover, while contemplating this issue, we must be aware that we do not only change the gene in one individual but also the future generations procreated by this individual. CRISPR editing has the potential of altering the natural course of human heredity.
We don’t blow up randomly nuclear bombs just because we can. Until we have a better understanding and an agreement in the worldwide society about the use of CRISPR should not be justified by “because we can.” Before trying to play God, we should all try to be good.
Categories: Neuroscience, Stem cells, UnScience
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