Is human genetic modification ethical?
Genetic engineering has long been a controversial topic. It can be traced back to 1953 when the double-helix structure of DNA was discovered and 1958 when DNA was first synthesized in a test tube. The next milestone is the creation of rDNA (Recombinant DNA) in 1972. rDNA is DNA that is created through a combination of elements of multiple DNA from different organisms, allowing researchers to take desirable traits from different organisms and eliminate unwanted drawbacks.
In 1981, the first transgenic animal was created when Ohio University Professor Thomas Wagner and his team transferred a gene from a rabbit into the mouse genome using DNA microinjection. This process involves using very small bore glass needles to inject DNA into a cell. This marked the first genetic modification of an animal to have more desirable traits.
There are 3 main genome editing technologies: clustered regularly interspaced short palindromic repeats (CRISPR), which is used in CRISPR-associated protein 9 (Cas9), transcription activator-like effector nucleases (TALENs), and zinc finger nucleases (ZFNs). While all three have their uses in genetic editing, Cas9 technology is the newest of the three methods and has been at the forefront of recent embryo gene editing.
Cas9 technology uses the immune system of bacteria to edit genes. CRISPR is a bacteria’s immune system and works similarly to the human immune system. It recognizes foreign invaders, takes a piece of the invader’s genome, and inserts it into the bacterium’s DNA. From that sequence, CRISPR creates a new sequence that helps find the invader via DNA sequence complementarity, where A binds to T and C binds to G.
CRISPR works in gene editing by transcribing a guide sequence into short RNA sequences that directs the system to matching parts of DNA. When this matching portion is found, Cas-9 – an enzyme produced by the system – binds to the DNA and cuts it, shutting off the targeted portion and causing it to no longer be expressed. This can be modified to activate gene function and cause previously deactivated genetic sequences to be expressed, and can therefore be used to target and modify mutations in DNA to treat genetic disease.
In November 2018, it was reported that two twin girls in China had been born with modified genes to make them HIV immune. Their genetic modification was the result of an experiment conducted by Chinese biophysicist He Jiankui with couples where the males were HIV carriers. Using CRISPR technology, Jiankui disabled the CCR5 gene that enables the HIV infection. However, Chinese government regulations banned research on human in vitro embryos after the 14th day of existence, in line with the regulations of many countries.
There are many advantages of embryo editing, such as preventing a child from being born with genetic diseases like cystic fibrosis or Huntington’s disease. Better screening and treatments can help people with cystic fibrosis live well into their 50s. This is expected to increase with developments in healthcare. However, for diseases like Huntington’s disease, which causes nerve cells in the brain to decay over time, there are no effective treatments to prevent the physical and mental decline caused by the disease. Therefore, genetic engineering of embryos may be the only way to prevent this disease.
On the other hand, embryo editing could lead to many ethical concerns, such as the creation of designer babies – babies that are genetically modified to have desirable traits through genetic editing. This could theoretically be accomplished using CRISPR technology to cut out and express genes that change the characteristics of the baby.
The future of embryonic editing is still shrouded in mystery because of how new the technology is. There are few guidelines and continued debate over how it should be handled and whether it should even be used.
It is clear that this technology will face many restrictions and challenges before it becomes mainstream. Sheila Jasanoff, founder of the Science, Technology, and Society program at HKS, has called for a global observatory in order to address gene editing and other emerging technologies.
Sources: Synthego, ScienceDirect, National Center for Biotechnology Information, Cleveland Clinic, Mayo Clinic, The Guardian, StanfordReport, BROAD Institute, The Harvard Gazette
