Author: Teodora Botin
Teo is a junior in high school at the Gheorghe Lazar National College, Romania, and has very ambitious goals. She loves to have fun with her friends and hopes she will become a cardiothoracic surgeon.
Imagine a future in which parents can create children with their desired characteristics, selecting the child’s height, eye colour, and hair colour as they please. In this futuristic world, farmers can grow drought-resistant plants, and cancer would be a sad memory of the past. Sounds like a summary of a sci-fi movie, but some of this is already happening!
Modifying genotypes and phenotypes is done through CRISPR, which stands for Clustered Regularly Interspaced Short Palindromic Repeats. CRISPR-Cas9 is a type of genome editing technology. In essence, it is a series of short repetitive DNA sequences with “spacers” placed between them. Bacteria use these genetic sequences to “remember” each specific virus that attacks them.
Before discussing the pros and cons of these predictions, how does CRISPR work? It’s important to remember that from the smallest single-celled organism to the largest creatures on earth, every living thing is defined by its genes. The DNA in our genes act as a guide for our cells. The DNA instructs the cells how to make proteins and dictates what those proteins will do within the body. Thus, if we can control our DNA, we can control how our body looks and acts! Essentially, four structural units called bases are joined in exact sequences, which tell the cell how to behave and represent the foundation of each of our traits.
Natural CRISPR uses two main components. The first component is short fragments of repetitive DNA called “clusters regularly interspersed with repeated palindromic sequences,” or more simply, CRISPRs. The next is Cas or “CRISPR-associated proteins” that cleave DNA like molecular scissors. When a virus invades the bacterium, Cas proteins remove a segment of viral DNA to stick to the CRISPR region of the bacterium, capturing a chemical image of the infection. These viral codes are then copied into short pieces of RNA, having many roles in our cells, but in the case of CRISPR, RNA binds to a special protein called Cas9. The resulting complexes behave like antibodies, which block free genetic material and try to bind to the virus. If the virus returns, this complex will recognize it immediately, and Cas9 will quickly destroy the viral DNA. Many bacteria have this type of defense mechanism.
But in 2012, scientists discovered how to “hijack” CRISPR to target not only viral DNA, but any DNA in almost every organism. Industries can use CRISPR as a tool: it can create new drug therapies for human diseases, help farmers grow pathogen-resistant plants, create new species of plants and animals – and even bring back those that have gone extinct.
Although there are many pros, people remain skeptical about genetic editing. We could change mosquitoes to stop transmitting malaria, we could create plants that produce bigger and tastier fruits, but we do not know the long-term effects. These genetic changes are passed on to offspring and as we do not have complete and long-term tests, the side effects will remain unknown for quite a while. In addition, there are issues related to ethics. Given the permanent nature of the change in a person’s genome, the FDA (Food and Drug Administration) is cautiously approaching CRISPR. Some scientists have even proposed a moratorium on research until more information is found about the potential impact on people.
Several experiments have been started in China, USA, Europe, including the CRISPR Therapeutics study which focused on a blood disorder known as beta-thalassemia, resulting in abnormal red blood cell production. Together with Vertex Pharmaceuticals in Boston, CRISPR Therapeutics officially began the first clinical trial of beta-thalassemia therapy in September 2018.
Although fairly innovative, this research was not the first to use CRISPR to manipulate human genetic material. In August 2017, a team led by biologist Shoukhrat Mitalipov of Oregon Health and Science University received private funding to use CRISPR-Cas9 to target a mutation in viable human embryos that causes thickening of the heart muscles. 72% of the modified embryos returned to the laboratory without mutation (higher than the usual 50% chance of inheritance).
Some critics argue that genetic editing of embryos is unethical, even if the edited embryos are not intended for transfer and implantation. This type of testing does not currently receive federal funding, but is based on funding from private donors.
However, one thing is for sure; CRISPR is an innovation and will represent the future of medicine, food, agriculture and biotechnology. The landscape of genetic editing could look completely different in 100, 50 or even 10 years. After all, CRISPR is the cheapest and fastest form of genetic editing. From farmers to researchers, this new technology will have a major impact on our society.
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How CRISPR lets you edit DNA – Andrea M. Henle. (2019, January 24). YouTube. https://www.youtube.com/watch?v=6tw_JVz_IEc
Robinson, E. (2017, August 2). Study in Nature demonstrates method for repairing genes in human embryos that prevents inherited diseases. OHSU News. https://news.ohsu.edu/2017/08/02/study-in-nature-demonstrates-method-for-repairing-genes-in-human-embryos-that-prevents-inherited-diseases
What is CRISPR? (2016, February 18). YouTube. https://www.youtube.com/watch?v=MnYppmstxIs
What is CRISPR? (2020). New Scientist. https://www.newscientist.com/definition/what-is-crispr/
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