Will genome editing with the new technology, CRISPR, usher in a new era of Promethean overreach? CRISPR makes altering the human genome widely available and cheap. But the fur is rising on the necks of anti-play-god bioethicists; they fear that geneticists will play god and precipitate a backlash from nature that could be disastrous to the human race. In contrast to the anti-play-god bioethicists, Ted Peters’ newly published article, “Should CRISPR Scientists Play God?” recommends that laboratory science invoke the Precautionary Principle (PP). With the PP in hand, laboratory researchers should pause at the yellow caution light. But then, with constant risk-assessment, proceed ahead.
Here is what you might want to know but really don’t need to. CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. What does this mean? In our evolutionary past, our human genomes incorporated palindromic DNA repeats from bacteria and archaea which are their adaptive method for strengthening their immune systems. The summary point to get is this: palindromic repeats of DNA base pairs provide targets for the geneticist to shoot at.
The CRISPR archer shoots at these targets with Cas9 arrows. What’s Cas9? It’s an endonuclease capable of cleaving DNA. When combined with specific RNA in a system it can either insert or delete specific genetic sequences. If Cas9 is the arrow, the CRISPR archer can fire it to a specific target on a DNA strand, cut it, insert a prescribed sequence of nucleotides, and then re-connect the DNA strand. We call this “gene editing” for short.
Here is the upshot. CRISPR/Cas9 technology can be used for highly specific and convenient gene editing, either inserting sequences in target genes, deleting genes, or turning genes off. The overwhelming scientific consensus is that this technology will usher in an age of cheap and easy genetic manipulation. If we don’t like the DNA nature has bequeathed us, we can employ CRISPR/Cas9 to edit it to our standards.
There are two important ways that CRISPR/Cas9 technology can improve human health and wellbeing. The first is somatic genome editing therapy. A patient suffering from metastatic non-small lung cancer, for example, may benefit. How might this work? We note that everyday our immune system engages cancer threats with a defense. When the defense is compromised, cancer wins. On the front line is the T cell which, like Achilles, leads the immune system into battle against cancer. This happens commonly. Right now while you’re reading this text the battle between your immune system and cancer is taking place. In persons with metastatic non-small lung cancer for whom chemotherapy and radiation have failed, however, scientists have observed that T cells are sabotaged from within by a Quisling enzyme, PD-1. By sending CRISPR/Cas9 into these T cells, clinicians are hoping to snip out the PD-1 gene and liberate the T cell. The T cell should then triumph once again in the cancer siege. By editing the genome of a living patient, this type of cancer might succumb to somatic genome editing therapy.
The second potential way in which CRISPR/Cas9 editing might contribute to human health is through germline editing. Our germ cells are found in eggs and sperm, where they are in a position to pass our DNA on through our children to many future generations. On the tip of chromosome 4, for another example, some sufferers from Huntington’s disease have a mutated gene (allele) which is responsible for untold suffering and crippling. Should a CRISPR scientist edit this gene in the germline, thereby eliminating it for this person’s descendents? Should our generation systematically eliminate this allele from the human gene pool, thereby eliminating this disease for everyone in the future?
“Whoah!” shouts the anti-play-god bioethicist. Why? Are the bioethicists heartless? Do bioethicists want to see Huntington’s patients suffer? No, that is not the reason. Their judgment is based on what we don’t know. What we don’t know is the long-term effect of such large-scale changes in the genome. Genes work with other genes and other DNA in delicate systems like Swiss watches, mutually influencing one another. To eliminate one set of gears in an old fashioned Swiss watch would cause it to self-destruct. Might this analogy apply to the human genome? We don’t know yet. Without this knowledge, clinical geneticists cannot measure the risk.
Without knowing the level of harm-benefit risk, the question arising among bioethicists is this: should we proceed to modify the germline in human beings (and plants or animals too)? On most days when such questions arise, the average bioethicist can get by with a single-word vocabulary. All he or she needs to do is pronounce the word “No,” with emphasis, and the job is done. If a bioethicist were to say, “Yes” too often, he or she would be shunned by colleagues as having sold out to the industry.
The PP to the rescue. Peters relies on the so-called Wingspread version of the Precautionary Principle as it was formulated at the 1992 United Nations Conference on Environment and Development: “When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. In this context the proponent of the process or product, rather than the public, should bear the burden of proof.” Although the PP applied originally to ecological ethics, it might apply equally well to gene editing.
Here’s what I recommend: “Yes, but not yet.” That’s a longer sentence than merely the word, “No”. “Yes, but not yet” might be the most appropriate ethical counsel we could offer to those geneticists attempting to ascertain the risk level of CRISPR editing of the human germline.
CRISPR/Cas9 puts us momentarily at a traffic stoplight. We have three options. Those who affirm Prometheus’ hubris and invoke the technological imperative―if we can do it we should do it!―want to race through a green light toward an enhanced humanity. The anti-play-god Promethean hopes that the light will remain red so all traffic remains stopped. The proceed-with-caution bioethicist looks both ways on yellow, but drives forward. Peters recommends the third.
For you who do not regularly read my blog, I am a fictional character in the thriller, For God and Country. I am a former CIA operative currently serving as a Lutheran pastor on the south side of Chicago. My doctorate from Michigan State University is in astrobiology and I give special attention to Society, Science, and Spirit.