Divided Opinions about CRISPR-cas Gene Editing
With the Chinese scientist’s gene editing scandal that shook the world in November, 2018, the Organising Committee of the Second International Summit on Human Genome Editing were forced to revise their human genome editing international ethical guidelines. This involves legalising CRISPR-Cas9 technology (“CRISPR”) on humans and embryos with use restricted to when there is an absence of ‘reasonable alternatives’.
With this step forward, an increasing number of researchers began to jump onboard to further test this technology in a flurry of human trials, particularly in US and Russia. This has widely been hit with unease from the public – “after that unethical issue with that scientist, why are scientists seemingly more motivated to perform gene-editing?”
Let’s first start with explaining the incident:
He Jiankui, the Chinese scientist responsible for this global uproar, used CRISPR to perform gene editing on multiple human embryos, the first one leading to the birth of twin daughters with HIV resistance.
CRISPR is still a fairly new technology, having first been repurposed from the original bacterial immune defence systems into eukaryotic systems for gene editing in 2013, for human and mouse cells.
The main concern is that this recent technology, although used extensively in both cell and animal models since its introduction, has not been used in humans, let alone embryos. This is a huge safety issue, especially considering what we know about CRISPR.
What’s wrong with CRISPR?
CRISPR is considered as the gene editing technique with the most precision, yet a common issue is that some cells may escape gene modification. But that’s just the tip of the iceberg, and is not the main problem which makes this technology so controversial.
One of the major complications of CRISPR-Cas9 gene editing technology is off-target snipping, responsible for editing errors.
What results from these editing errors? Not a Frankenstein’s monster, and also not a Winter Soldier. Rather, off-target mutations can cause vulnerabilities in those DNA sequences, and can predispose the person to cancer.
However, this issue has now been targeted for improvement, via this just-as-major breakthrough. Not that He Jiankui had access to this when he performed his experiments on human embryos. This new version involves the addition of another RNA sequence to the guide RNA-CRISPR molecule to enhance precise targeting and cleavage of DNA by the Cas9 enzyme, improving the accuracy of this technology – and hence lowering the chance of off-target mutations.
The other major complication? The effect of successfully editing the targeted gene.
Although there have been many studies involving gene editing in cells and in other species, the interplay between genes in humans are not completely understood. We understand some direct links between gene and causation quite well in some instances, but indirect links are less understood.
Editing of one gene, such as CCR5 in this 2018 case, may confer innate immunity against some forms of HIV, however, there is current controversy about how this predisposes the twins to be more susceptible to the flu. This further leads to greater public concern about the safety and ethics of CRISPR.
But on the other side of the coin of the public’s negative perspectives of gene editing, is a whole different story for the people requesting for it.
In the eyes of these cancer patients which CRISPR is currently being trialled on in America, they have hopes that this technique would be successful, and hence cure their cancer and prolong their lifespan.
Even in the eyes of the Chinese parents whose twin daughters were the experimental results of the scandalous Chinese researcher, they were thankful, as the father had HIV which he did not want to pass onto their children. Not only were the couple offered free IVF and sperm washing to remove the HIV virus, their daughters who were gene edited at the CCR5 gene are now immune against the most common form of HIV. Furthermore, He Jiankui claims that the parents themselves chose the option of implanting the gene edited embryos rather than the unedited embryos.
So what do you think about this technology? Do you support it or are you against it now that you know the facts about it? Or would you rather place your hopes in the newly found alternative which targets RNA instead of DNA, called ‘LEAPER’?
A great video about CRISPR trials for cancer patients beginning in US (requires LinkedIn login) is:
On the other hand, if you want to read about the World Health Organisation (WHO)’s point of view which I didn’t mention, this is a really short and simple read: