Just when genetically modified (GM) mosquitoes got their approval by the Cayman Islands and the government of Canada's Prince Edward Island is trying to approve GM salmon, research reveals unexpected and potentially dangerous effects of genetic engineering
Unfortunately, neither the makers of genetically modified organisms (GMOs) nor their regulators conduct the studies that are necessary to protect the public. Being bitten by GM mosquitoes and eating GM salmon remains a serious gamble.
The discomfiting research published in Nature Methods examined the unintended impacts of gene editing on the DNA of mice. Gene editing is touted by its promoters as the safer, more precise version of genetic engineering. The earlier version that was used to create the GM crops we all know about (soy, corn, etc.) forced genetic material from bacteria or viruses into plant DNA. Gene editing, on the other hand, does not necessarily introduce genes from foreign species. Rather, it cuts the DNA in a predetermined location. The cell's DNA repair mechanisms are then activated to repair the cut.
Of all the gene editing techniques, the one that is easiest, least expensive, and most popular is called CRISPR-Cas9. Proponents claim it is so safe and predictable, it should not be regulated. They want to put their gene-edited products on the market without informing governments or consumers. And they don't even want it to be called genetic engineering, since consumers have largely weighed in against GMOs. That is why the research is so damning.
Gene Editing Creates Predictable Mutations
The tools used for gene editing are designed to recognize and make changes only on specific DNA sequences. In the Nature Methods research, for example, the engineers designed their tools to fix a defective DNA sequence that could restore sight to blind mice. But the defective DNA sequence that governs sight is also repeated in other places throughout the mouse genome--unrelated to vision. Therefore, the gene editing tools can also make unintended changes in these "off-target" locations.
The unwanted mutations do not come from cutting the DNA. Rather, they occur when the cut ends are rejoined by the cells' repair mechanisms. It results in either the loss of some DNA base units or the insertion of a few base units at the cut site.
If the mutation occurs in the middle of a known gene (or in a portion of the DNA that controls a gene) it can severely disrupt its function. Gene editors, therefore, rely on computer models of the genome to identify where the similar sequences are that are likely to become mutated and to predict what level of collateral damage that could create. If the risk is considered low enough, they proceed with editing.
Widespread Unpredicted Mutations Discovered
There is a joke that says molecular biologists don't understand just two things: molecules and biology. Too often, the complex 3-D world doesn't cooperate with their computer model predictions. This was again confirmed by the work of Stamford's Dr. Kellie Schaefer, along with her colleagues from Stamford, Columbia, and the University of Iowa.
Instead of letting the computer guess which off-target changes would take place, Schaefer's team actually sequenced the genome of the two gene-edited mice after they had undergone CRISPR-Cas9. They did find insertions and deletions (indels), which is the type of mutation that the computer predicts. One mouse had 164 indels; the other 128. But of the top 50 sequences that a computer would identify as most likely to be mutated, none were changed at all. Far more importantly, however, the computer model would totally miss their other finding: point mutations throughout the genome. One mouse had 1,736; the other 1,696.
A point mutation is the replacement of a single nucleotide along the DNA. But don't let its smallness fool you. These so-called single-nucleotide variants (SNV) can have huge consequences. They can lead to many types of changes, including disease.
According to Dr. Michael Antoniou, a London-based molecular geneticist who routinely uses genetic engineering in his research, "Many of the genome editing-induced off-target mutations [both the point mutations and the indels] . . . will no doubt be benign in terms of effects on gene function. However, many will not be benign and their effects can carry through to the final marketed product, whether it be plant or animal." This could translate into possible toxins, allergens, carcinogens, or other changes that could affect those eating a GMO.
Dr. Michael Hansen, a Senior Scientist at Consumers Union, the policy arm of Consumer Reports, wrote, "While genome editing has been portrayed in the media as an incredibly precise process, where one can go in and literally only intentionally change one or a small number of nucleotide bases, the reality is that there can be large numbers of off-target effects." He says, "This study raises troubling concerns."
Another study in Nature Communications used CRISPR/Cas9 to make 17 edits in the mouse genome. They too sequenced the genome and found unexpected insertions and deletions in all 17 places. Whereas deletions of approximately 9 base pairs are predicted, the actual size of the deletions was as high as 600 base pairs. No computer model predicts DNA damage this extensive.
A third study published this year also found deletions of more than 500 base units. The researchers also confirmed that proteins produced by these mutated sections were altered. Such changes could theoretically transform a beneficial protein to a harmful one.
Hansen says the long deletions of DNA material "may not be routinely identified without whole genome sequencing." But whole genome sequencing is rarely done by gene editors. Instead, they rely on their computers.
Even if they did sequence the genome, science doesn't yet have the capacity to predict what the real-life consequences of all the mutations would be. Therefore, according to Antoniou, "it is also essential to ascertain the effects of these unintended changes on global patterns of gene function." For this, both Antoniou and Hansen (as well as the National Academy of Sciences and the international standard setting body Codex Alimentarius) agree that the scientists must also analyze the changes in RNA, proteins, and metabolites.
Armed with this data, certain problems would be obvious--an increase of a known allergen or toxin, for example. But even if no red flags are raised at this point, according to Antoniou, "it is still necessary to conduct long-term toxicity studies" using animals. That's because, once again, science is still not competent to figure out the complex interactions and side effects that can occur.
Antoniou concludes, "In the absence of these analyses, to claim that genome editing is precise and predictable is based on faith rather than science."
And it is mere faith that supports the claims that GM mosquitoes and salmon are safe. Although they were not produced by the CRISP-Cas9 technique, they are the product of earlier gene-insertion techniques, which are also fraught with unpredictable mutations and altered gene expressions.
Earlier Research Warnings Ignored by GMO Makers
Just because this year's research on gene editing shows unintended and potentially dangerous side effects does not mean that companies using the technology will change the way they operate. Indeed, back in 1999, a study showed widespread changes in the DNA due to gene insertion; but many GMO companies conveniently ignored the findings and continue to do so.
In that study, scientists studying cystic fibrosis inserted a gene into human cells. Using a microarray, they discovered that the insertion "significantly affect[ed] up to 5% of the total genes in the array." This means that the presence of a single foreign gene might change the expression of hundreds, possibly thousands of genes. In the case of the human cell being studied, the scientists were at a loss to determine the impact. "In the absence of more biological information," they wrote, "we cannot discern which directions are better or worse, since any of these may have positive or negative effects."
Just like the gene editing studies, this 1999 discovery contradicted the assumptions of an entire industry, which marched forward on the false assumption that their GMOs were predictable and safe.
The Untested Danger of a GM Mosquito Bite
In January 2014, I testified at the Florida Keys Mosquito Control District, opposing their planned release of GM mosquitoes. Also testifying was Derric Nimmo, a principal scientist at Oxitec, the UK company that produces the mosquitoes.
Oxitec had already conducted limited releases with millions of Aedis Aegypti mosquitoes in the Cayman Islands, Brazil, Panama, and Malaysia. The male insects were engineered to mate with natural females and produce offspring that die before reaching adulthood. Their plan was to reduce the population and thereby reduce the incidence of dengue and other diseases that this type of mosquito carries.
The company had widely publicized that they were only releasing males, which don't bite. But it turns out that their method of sorting males from females is flawed, and thousands of biting female mosquitoes are released. In addition, their method to create non-viable offspring is also flawed. Between 3%-15% of the offspring survive and prosper. This can easily translate into millions of biting females, born from a genetically engineered family tree.
After the Florida hearing was over, I asked Derric if they ever analyzed the saliva from their GM mosquitoes, since the saliva enters the bloodstream of the people who are bitten. He said that they were just now doing research to see if the protein produced by the inserted gene was found in the saliva.
Realizing that they had already exposed the population of four countries to their mosquito saliva before doing this research, I was unimpressed. Then…
I explained to Derric the findings of the cystic fibrosis study, showing that a single inserted gene can create widespread changes, including toxins, allergens, or carcinogens. Shouldn't his company analyze everything in the saliva, I asked? Derric responded, "Good idea."
ln Derric's defense, Oxitec is not the only company that is tampering with nature's gene pool in spite of the fact that it is wholly unprepared and unqualified to do so. Other GMO makers also fail to use the modern molecular profiling techniques that reveal unintended side effects. However, when independent scientists conduct that type of research on GMOs, the results are sobering.
For example, long after Monsanto's Roundup Ready corn had been consumed by hundreds of millions of people, a team led by Dr. Antoniou found more than 200 significant changes in its proteins and metabolites, compared to non-GMO corn of the same variety. Two of the compounds that increased are aptly named putrescine and cadaverine, because they produce the horrific smell of rotting dead bodies. More worrisome; they are also linked to higher risks of allergies and cancer. Another Monsanto GM corn has a new allergen and their cooked soy has up to seven times the level of a known soy allergen, compared to cooked non-GMO soy.
The Typical Biotech Response: Ignore or Attack
If regulators and medical authorities knew in advance that a proposed GMO contained new or higher levels of dangerous allergens, it is unlikely that the GMO would have been introduced. (I'm being optimistic.) But once a GMO variety is released, grown on millions of acres and eaten by millions of people, somehow the crop enjoys a bizarre immunity. Confronted with hard evidence of allergens, GMO makers and government regulators typically ignore the problem. The offending GMOs are still on the market, and they don't carry any warnings on the package to protect those who might react.
If independent scientists discover an adverse finding that might threaten their bottom line, companies like Monsanto enlist a veritable army of supporters to drum up opposition--often using unscientific excuses that are repeated so often that they appear to be facts.
Two gene-editing companies whose stocks plummeted after the Nature Methods article came out quickly mounted their attack. But according to GMWatch.org, "the findings reported in the article, along with other research papers that also report unintended effects of CRISPR gene editing, show that the companies are arguing on the wrong side of the science."
The main argument used by the company Intellia was that the mutations were not from the gene editing at all. They claim that "the more plausible conclusion is that the genetic differences reflect a normal level of variation between individuals in a colony." But the scientific literature does not support this conclusion, given that:
Most of the mutations (117 indels and 1397 SNVS) were exactly the same in the two mice. According to GMWatch.org, "This indicates a targeted and non-random process." If it were "a normal level of variation," as Intellia insists, there would be much greater difference between the mice.
Another study looked at the genomes of 36 different strains of mice. None of the point mutations that were found in the gene-edited mice were in any of these strains. Thus, they don't appear to be naturally occurring at all.
In fact, the sheer number of mutations in the edited mice was higher than scientists find among natural strains.
Perhaps the most strained logic used by Intellia to attack the research was that "there is no known mechanistic basis for Cas9 to induce SNVs." In other words, the journal should not have published research showing unpredicted changes in the DNA simply because no one yet has figured out why those changes take place.
But if these widespread mutations exist in Crispr-Cas9 edited organisms, according to Antoniou they are likely happening with all the new gene editing techniques, which haven't yet been studied in such detail.
Real Dangers and Perceived Dangers are Both Dangerous
If we apply these lessons to GM mosquitoes, there are serious consequences. If the saliva contains a new toxin or allergen, it might elicit mild or even deadly reactions. Since there are no human clinical trials and no public health surveillance related to the mosquito, the cause of any associated health problems could go unnoticed. It would require a large-scale outbreak of a serious reaction for health authorities to even mount an investigation, let alone consider the mosquito as a potential source.
Whether or not the GM mosquito causes harm, there is another problem that the Cayman authorities have surely overlooked. Suppose a girl who is vacationing on the island has a sudden onset of a serious health issue without an apparent cause. And suppose that her parents notice that she has also been bitten by mosquitoes. Now suppose that they draw the conclusion, correctly or incorrectly, that her condition is caused by the bite of a GM mosquito and that story is picked up by the media.
It doesn't have to be a prominent media source for it to inspire some supermarket tabloid to dream up alarming headlines about the serious threat to American tourists by deadly engineered mosquitoes. The results could be disastrous for Cayman tourism.
The Cayman government is not only gambling that GM mosquitoes are safe (which cannot be guaranteed at this point), but also that no one draws the conclusion that they got harmed from being bitten by one. Who would want to vacation on an island where a mosquito bite could lead to who knows what?
It's the who-knows-what that is the main point here. No one knows. But now that we understand that the generic genetic engineering process that created the mosquito also creates unpredictable and potentially dangerous changes, who in their right mind would release them? Oxitec would, obviously. And they still haven't published any research on the composition of their GM mosquito saliva.
Oxitec is also planning to release genetically engineered moths in upstate New York. The male moths, like the mosquitoes, mate with natural males and produce larvae that don't make it to maturity. But that larvae will inevitably be deposited into cabbage, cauliflower, and broccoli. What if the genetic engineering process alters the larvae and creates a toxin or allergen? Eating that vegetable might trigger a reaction. And just like the mosquito bite, it would be hard to trace, and the perception of harm (real or unreal) could damage produce sales from regions near the moths' release.
Oxitec is owned by Intrexon, which also owns AquaBounty--the maker of GM salmon. The research on the salmon did show indications of off-target effects, with higher amounts of a cancer promoting hormone (IGF-1) and larger allergenic potential. But the number of fish used in the study was so small that the changes were not statistically significant. On behalf of Consumers Union, Hansen wrote to the FDA, "Because FDA's assessment is inadequate, we are particularly concerned that this salmon may pose an increased risk of severe, even life-threatening allergic reactions to sensitive individuals. Instead of approving this product, FDA should be requiring studies with data from many more engineered fish, not the tiny sample of six fish on which it currently bases its conclusions. Unfortunately, even the data from those six fish raises concerns." The FDA did not heed Hansen's warning and instead approved the salmon for consumption.
At this point, there are no comprehensive analyses or feeding studies on any of these Intrexon GMOs. Their release might not only affect human health, they can permanently alter the gene pool. If the salmon escape confinement into the ocean, if the surviving GM mosquitoes or moths persist, there is no technology on earth to recall them. Any side effect can be with us for generations.
Although GMO companies like to argue that GMOs with built-in sterility will not persist in the environment. Given the fact that a percentage can survive, however, their argument is deceptive. In addition, studies confirm that after several generations, genetically engineered traits in insects can fail. A study, for example, showed that newly introduced traits in engineered mosquitoes failed in just 25 generations.
Intrexon can't pretend it doesn't know about the dangers and problems with genetic engineering technology, both real and perceived. Robert Shapiro has been on their board since 2011. He was the CEO of Monsanto who arranged to fast track the release of GMOs into the food supply. Monsanto inserted the company's attorney into the FDA, where he pioneered the policy that allows GMOs onto the market without a single adequate safety study. Since then, numerous studies have pointed to serious health impacts, all of which are ignored or attacked.
Many of us who study the research on GMOs are convinced that they contribute to rising disease rates in the US. But even if we're wrong, no one can pretend that the GMOs have been safe for the economy. All over the world and especially in the US, consumer rejection of GMOs has exacted a heavy economic toll on food companies and agribusiness.
But even if the regulators in the Cayman Islands and Prince Edward Island are ignoring the trends, others are wising up. According to Friends of the Earth, "more than 79 grocery retailers with more than 11,000 stores have now made commitments to not sell the GMO salmon," if it gets introduced into the market. Major brands are already racing to eliminate derivatives of GM crops, even advertising on TV that their products are non-GMO. And many countries and regions that had considered Oxitec's GM mosquitoes have said no and are opting for safer alternatives. And as long new studies continue to demonstrate serious unpredicted side-effects from genetic engineering, more consumers will take the necessary precautions.