Social Impact of Genome Editing
While there has been much excitement about the potential for using genome editing to solve current challenges in agriculture and medicine, the eventual and long- term impact of this technology will require very careful consideration (Singh et al., 2016). Would correcting defects in genomes of people who have incurable diseases such as cystic fibrosis, muscular dystrophy, Parkinson’s or Huntington’s disease resulting from an accident of birth not meet with universal acclaim? Would removing the human suffering caused by vectors of otherwise unstoppable pathogens such as Zika virus not constitute obvious progress for the human species? Or do such transformations of nature exemplify the hubris of ‘playing God,’ inducing a slippery slope of ethical degeneration, leading to ‘designer babies’ with enhanced traits and the permanent alteration of human evolution as a whole (Krishan et al., 2016)? Would making corrections in the genomes of people who were previously doomed from birth not entice others to alter the genomes of their offspring as embryos, for example, to target genes that are linked to cancer or to other chronic diseases (Regalado, 2015, Benston, 2016). Is it not a short ethical jump for would-be parents to play an active role in determining their children’s appearance, intelligence and athletic abilities once the potential is proven (Sankar and Cho, 2015, Shantharam, 2016)?
As with all technological change, societies seek a balance between risk and utility through some acceptable social consensus. On the utility side of the equation, genome editing offers a quantum leap from transgenesis in potential. The same is arguably true on the risk side of the equation once gene drives are on the table. There is no way to predict confidently the downstream effects of genome editing over multiple generations. For example, off-target effects of genome editing, meaning the editing of additional unintended sites on the genome, could result in dramatic changes to an organism’s health not necessarily in the short term, but possibly in the long run, such as turning proto-oncogenes on, other essential genes off or even creating new genetic defects. While CRISPR-Cas9 can be used to modify epigenetic effects, its use may also create new conundrums with unpredictable consequences. Long-term animal studies have not yet been completed and in any event would not conclusively settle the incremental risk of genome editing in humans (Vogel, 2015). This is not pure speculation; Chinese scientists have begun experiments with editing human genomes (Liang et al 2015). Finally, might nature resist being re-ordered as organisms develop resistance to alterations made by gene drives (Callaway 2017)?
These profound ethical questions for society have less dramatic analogues in agriculture. Altering the course of evolution of both crops and pests fundamentally, for example, by inducing resistance to viruses and other pathogens that reduce yields and incomes in the field, or inducing resistance to drought in some plants and not others becomes conceivable. We could without question generate crops enhanced for disease resistance and improved nutritional content — an attractive consideration for our soon-to-be more crowded and hotter planet. Genome edited crops are simple to generate, low in cost to produce, and leave no trace of transgene backbone or selectable markers. The fact that technologies such as CRISPR-Cas9 are derived from the same bacteria which already naturally reside in the human gut makes it difficult to claim that anything ‘foreign’ has been included in the editing process. On average, only one or a few nucleotides are altered in many genome-edited crops, perhaps decisively differentiating them from ‘GMOs’ (Paul and Qi, 2016). In fact, as the first genome edited crops begin to attract public interest, there seems to be no consensus on how to classify them.
For example, non-browning mushrooms developed through genome editing technologies via the biotech company Calyxt entered the market with no serious disturbance or resistance from anti-GMO protestors (Waltz, 2016). This trait was achieved by deleting a few nucleotides from the gene that causes browning within the mushroom’s genome. No sequences of plant pests, such as viruses or bacteria that are often associated with GMOs, were included in the editing process. Waxy corn has also been given the green light by the US regulatory system for commercialization since no genetic material from a separate organism had been inserted into the plant genome (Unglesbee, 2016, Ossola, 2016). Although genome-edited crops do not invoke the same regulations as GMOs, some could argue that it is too early to tell how edited crops and livestock would impact our ecosystems and environment. If we change the genomes of pigs for example, so that they were no longer susceptible to influenza virus, would there be unintended consequences down the line for how the virus evolves, and therefore for human health? The immediate benefits with respect to disease burden seem huge, but what would be the ecological impact in the long term? If we can generate plants that are able to tolerate a spectrum of herbicides, what would be the net effect on environmental sustainability? How would we know?
These questions can be compared to many of the concerns raised with respect to genetically modified crops created with the use of existing technologies. A glance at current international policies regulating GMOs seems to be a good place to start.