CRISPR/Cas 9 is a gene editing technology that has changed biomedical research because it allows scientists to more rapidly and accurately “cut and paste” genes into DNA. CRISPR, which stands for Clustered Regularly Interspaced Short Palindromic Repeats, can find a specific DNA code and make a precision cut to break it apart when used in conjunction with a protein Cas9 . Because scientists can tune CRISPR to target any genetic sequence, genes can be added, deleted, or replaced with new genes, resulting in a new genetic sequence [1].
CRISPR essentially gives scientists the ability to control and modify DNA – the fundamental code of life. There is no question that CRISPR is a powerful tool for gene editing in the future and has great potential to lead to amazing advancements in many fields, including prevention and treatment of human diseases. Jennifer Doudna, PhD, who is lauded as the developer of CRISPR described it as a “a tool that scientists and clinicians around the world are using to understand our genetics, the genetics of all living things, and — most importantly — to intervene in genetic disease.” [2].
In theory, CRISPR could let us edit any genetic mutation to cure any disease with a genetic origin. The potential for CRISPR to treat genetic disorders is undeniably exciting. There are endless applications for genetic manipulation that will be beneficial for public health. For example, scientists at Washington University in St. Louis used CRISPR-Cas 9 gene editing to convert stem cells into working beta cells that reversed diabetes [3]. Scientists at University of Texas Southwestern Medical Center developed a CRISPR gene editing technique that could potentially correct the mutations that cause Duchenne muscular dystrophy [4]. And most recently, Columbia University in New York used an experimental CRISPR gene editing treatment in a patient with sickle cell disease, which has showed promising results as the patient has not had a single crisis since the treatment [2].
However, our society must be mindful that this gene editing technology comes with serious ethical implications when it is performed on germ cells – the egg and sperm which eventually give rise to all the cells in the body. These germ cells inevitably shape the traits the child will have and the characteristics that will be passed down to future generations.
In 2018, a Chinese scientist, He Jiankui, reportedly used CRISPR gene editing technology in human embryos to make twin girls immune to HIV infection, the virus that causes AIDS. This was accomplished by deleting the CCR5 gene from the girls’ DNA. However, deleting the CCR5 gene may have also improved the girls’ intelligence as there is a link between CCR5 and cognition. Studies have revealed that removing this gene in mice has made mice more intelligent and improved memory [5].
While this sounds like a positive collateral benefit, it caused quite an uproar in the scientific ethical community which largely objected to using genetic manipulations to enhance intelligence. However, up until this time, the scientific community still has not developed a consensus or regulations for the use of gene editing. Currently, and possibly dangerously, the uses of gene editing fall within the discretion of the researchers and their respective institutions. Our society needs clear consensus and guidelines on the use of genome editing for the future. If we allow gene editing to go on unchecked, there is real potential that this will result in inequity.
Some people may argue that many advancements in medicine have been “by accident” and that those incidental side effects have been accepted and even embraced by our healthcare system. For example, finasteride, a medication used to treat a prostate disorder, had an accidental side effect of promoting hair growth in male pattern baldness. This accident turned into a whole new drug, Propecia, targeted just for hair growth (6). Botox was initially used as a treatment for strabismus, a cross-eyed condition, but has become much more well known for its wrinkle reducing effects on aging skin [7].
However, there is a big difference between the use of Botox and Propecia for enhancement of a single patient exercising a personal choice, and those gene editing modifications of base cells of the unborn for the purpose of creating beneficial traits which will be passed down from generation to generation. While Botox and Propecia may be used to enhance one particular individual, CRISPR genetics has the potential to enhance the traits of multiple generations. Also “[t]here is a major distinction between somatic cell editing, which is the altering of often disease-causing genes that are not involved in reproduction, and germline editing, which changes inheritable traits”. [4]. At first blush, it may not seem like multi-general enhancements are a bad thing. But when we focus on who will actually have access to CRISPR editing, it becomes clearer that multi-generational enhancements will result in additional societal inequities.
As CRISPR is still in the experimental stages, it will likely cost a fortune. This begs the question of who will have access to these advanced gene therapies. In a society where the underprivileged already struggle with health equality and accessibility, CRISPR technology creates another avenue which places humanity at a crossroads. If we allow for altering of genetic traits, only the wealthy will have access to this technology. Where only the wealthy can afford gene editing, we may be heading towards a future where the wealthy will be able to make their children genetically superior. Genetically superior children could be smarter, more attractive, or could have perfect pitch giving them access to better jobs, celebrity status and more wealth. This will explode our already rising income inequality and the existing health disparities between the rich and poor.
At the present time, there is no general agreement on the acceptable uses of CRISPR. Moving forward, there needs to be limits on using CRISPR for manipulating inheritable traits, like height, intelligence, or appearance. The responsible thing is for our scientific community to come up with clear governance and oversight before gene editing technologies become the proverbial genie out of the bottle.
References:
M. Redman, A. King, C. Watson, D. King, “What is CRISPR/Cas9?”, Arch Dis Child Educ Pract Ed, 2016 August; 101(4)213-215. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4975809/
B. Balch, “The future of CRISPR is now” (December 2, 2021). https://www.aamc.org/news-insights/future-crispr-now.
A. Liu, “Reversing diabetes with CRISPR and patient derived stem cells” (April 22, 2020), https://www.fiercebiotech.com/research/reversing-diabetes-by-applying-crispr-to-patient-derived-stem-cells (
“New CRISPR method efficiently corrects Duchenne muscular dystrophy defect in heart tissue” (February 6, 2018). https://www.sciencedaily.com/releases/2018/02/180206121017.htm.
A. Regalalad, “China’s CRISPR twins might have had their brains inadvertently enhanced” (February 21, 2019). https://www.technologyreview.com/2019/02/21/137309/the-crispr-twins-had-their-brains-altered/
N. Saleh, “5 Weird but beneficial side effects of common drugs” (April 28, 2021). https://www.verywellhealth.com/beneficial-side-effects-of-common-drugs-4078471
E. Langer, “Alan Scott, researcher who pioneered medical uses of Botox, dies at 89” (December 21, 2021). https://www.washingtonpost.com/obituaries/2021/12/21/botox-doctor-alan-scott-dead/