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Genetic Editing of Animals Has Horrible Side Effects

Written by Dr. Joseph Mercola Fact Checked

crispr gene editing

Story at-a-glance -

  • Unlike GE foods, which may have genes from other species inserted, gene editing involves altering an organism’s DNA
  • Researchers have used CRISPR-Cas9 and other gene-editing technologies to create cows that can tolerate warmer temperatures, goats with longer cashmere wool and rabbits and pigs with bigger, leaner muscles
  • Serious side effects resulted as a byproduct of the genetic editing, including enlarged tongues in the rabbits
  • Among pigs that were altered by deleting the myostatin (MSTN) gene, which limits muscle growth, the larger muscles came along with an extra vertebrae in 20 percent of the gene-edited animals
  • Gene editing, with its loose regulation, accessibility and quick results, has been called the next “food revolution,” but many questions remain regarding its safety for human health and the environment

Would you eat a burger made from a cow with lab-altered DNA? How about a potato or a piece of salmon that was similarly tweaked? Gene-editing technologies are here, and they're already being used to alter the food supply.

For instance, gene-edited crops, in which DNA is tweaked or snipped out at a precise location, include soybeans with altered fatty acid profiles, potatoes that take longer to turn brown and potatoes that remain fresher longer and do not produce carcinogens when fried.

Genetically engineered (GE) salmon, dubbed “frankenfish,” which are engineered to grow about twice as fast as typical farm-raised salmon, not only exist but are already being sold and eaten in Canada, to the tune of 5 tons in 2017 alone (none of which was labeled as such).1

The next step that biotech companies are racing to bring to the not-so-proverbial table is gene-edited farm animals. Unlike GE foods, which may have genes from other species inserted, gene editing involves altering an organism's DNA. Like GE foods, however, gene-edited foods come with unknown risks to the animals and the people who eat them.

Gene Editing Led to Enlarged Tongues, Extra Vertebrae and Other Side Effects

While scientists have made great strides in mapping out genomes of entire organisms, much remains unknown about the purpose of individual genes and how they interact with one another. As such, making tweaks to genes, even those intended to be precise, often lead to surprising and unintended consequences.

In the case of livestock, researchers have used CRISPR-Cas9 and other gene-editing technologies to create cows that can tolerate warmer temperatures (so they can be raised in the tropics), goats with longer cashmere wool and rabbits and pigs with bigger, leaner muscles. Serious side effects resulted, however, including enlarged tongues in the rabbits.2,3

Among pigs that were altered by deleting the myostatin (MSTN) gene, which limits muscle growth, the larger muscles came along with an extra vertebra in 20 percent of the gene-edited animals.

“This result provides us a new insight to better understand MSTN’s function in both skeletal and muscle formation and development in the future studies,” the researchers noted, adding, “This phenomenon has never been reported in other MSTN-mutant animals."4 And therein lies the problem.

Genetic tweaking is not an exact science, and often researchers don’t know the extent of a gene’s functions until something like an extra vertebra reveals itself. Lisa Moses, an animal bioethicist at Harvard Medical School’s Center for Bioethics, told The Wall Street Journal:5

"Humans have a very long history of messing around in nature with all kinds of unintended consequences … It's really hubris of us to assume that we know what we're doing and that we can predict what kinds of bad things can happen."

Gene Editing Is Being Used to Alter Physical Traits, Puberty and Diseases in Animals

Along with altering DNA to create meatier or more temperature-tolerant animals, researchers have snipped out a section of pig DNA intended to prevent Porcine Reproductive and Respiratory Syndrome (PRRS) — a common and often fatal ailment among CAFO (concentrated animal feeding operation) pigs.6 Such edits are permanent and passed down to other generations.

In another project, this one funded by the U.S. Department of Agriculture, researchers have added the SRY gene to cattle, which results in female cows that turn into males, complete with larger muscles, a penis and testicles, but no ability to make sperm.7 Male (or male-like) cattle are more valuable to the beef industry because they get bigger, faster, allowing companies to make greater profits in less time.

Other biotech companies have taken to targeting genes intended to ease animal suffering, which they believe may soften regulators and consumers who are wary of the technology. "It's a better story to tell," Tammy Lee, CEO of Recombinetics, told the New York Post.8

The company has snipped out the genes responsible for growing horns in dairy cows, for instance, which means they wouldn't be subjected to the inhumane ways the horns are currently removed (with no pain relief).

Currently, cows born with the hornless trait are being raised at the University of California, Davis, with plans to eventually test their milk for any oddities. The company is also working on editing genes so pigs don't go through puberty. This would make castrating pigs — an inhumane procedure currently done (also without painkillers) to prevent meat from gaining an unpleasant odor — unnecessary.9

Recombinetics and other biotech companies don't want gene-edited foods to come with any warnings or additional regulations, which could hamper the technology's progress and acceptance by farmers. Once this occurs, though, it's likely that gene-editing will be used less for humanity's sake and more to create larger profits, such as via gene-editing to increase litter size.10

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What Are the Consequences of Eating Gene-Edited Foods?

Foods produced via gene-editing are not subject to regulation by the U.S. Department of Agriculture (USDA) — although an advisory board recommended gene-edited foods could not be labeled organic — or other regulatory agencies.11

In fact, in March 2018, the USDA released a statement noting that it would not regulate CRISPR-edited crops, noting, "With this approach, USDA seeks to allow innovation when there is no risk present."12

Gene editing, with its loose regulation, accessibility and quick results, has been called the next "food revolution,"13 at least for plant foods, but it's unclear whether the same will hold true for animals. In the U.S., it's been proposed that gene-edited foods do not need to be labeled, either, but the European Union ruled that they should be regulated the same as genetically modified organisms (GMOs).

Jaydee Hanson, an analyst at advocacy group the Center for Food Safety, told National Geographic that this may be closer to reality. "This is the new kind of genetic engineering, whether you call it transgenic [GMO] or not. It should be adequately regulated. We're not saying it should be stopped — we should know what has been done."14

As for what the health effects of eating gene-edited foods may be, no one knows. In an interview with GM Watch, Michael Antoniou, a London-based molecular geneticist, explained that significant changes could occur due to genetic editing, in both agricultural and medical contexts, necessitating long-term safety and toxicity studies. He explained:15

"Many of the genome editing-induced off-target mutations, as well as those induced by the tissue culture, 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 …

Thus not only is it necessary to conduct whole genome sequencing to identify all off-target mutations from CRISPR-based genome editing, but it is also essential to ascertain the effects of these unintended changes on global patterns of gene function.

… In addition, it is important to acknowledge that the targeted intended change in a given gene may also have unintended effects. For example, the total disruption or modification of an enzyme function can lead to unexpected or unpredictable biochemical side-reactions that can markedly alter the composition of an organism, such as a food crop.

The compositional alterations in food products produced with genome editing techniques will not be fully revealed by the molecular profiling methods due to the current inherent limitations of these techniques. So it is still necessary to conduct long-term toxicity studies in established animal model systems. In the absence of these analyses, to claim that genome editing is precise and predictable is based on faith rather than science."

Gene Editing May Not Be as Precise as It Seems

Researchers at the U.K.'s Wellcome Sanger Institute systematically studied mutations from CRISPR-Cas9 in mouse and human cells, focusing on the gene-editing target site. Large genetic rearrangements were observed, including DNA deletions and insertions, that were spotted near the target site.

They were far enough away, however, that standard tests looking for CRISPR-related DNA damage would miss them. The DNA deletions could end up activating genes that should stay "off," such as cancer-causing genes, as well as silencing those that should be "on."16

CRISPR-Cas9 also leads to the activation of the p53 gene, which works to either repair the DNA break or kill off the CRISPR-edited cell.17 CRISPR actually has a low efficacy rate for this reason, and CRISPR-edited cells that survive are able to do so because of a dysfunctional p53.

The problem is that p53 dysfunction is also linked to cancer (including close to half of ovarian and colorectal cancers and a sizable portion of lung, pancreatic, stomach, breast and liver cancers as well).18

In one recent study, researchers were able to boost average insertion or deletion efficiency to greater than 80 percent, but that was because of a dysfunctional p53 gene,19 which would mean the cells could be predisposed to cancer. The fact remains that while these new technologies are fascinating with enormous potential to change the world, they're highly experimental and the stakes are high.

In 2018, He Jiankui, a Chinese scientist, claimed to have created the world's first gene-edited babies. Although the claims haven't been vetted, Jiankui says he modified the DNA of human embryos during in vitro fertilization by disabling a gene called CCR5, which could potentially make the babies resistant to infection with HIV.20

Americans Don't Want Frankenfish — Why Would They Want 'Frankenmeat'?

In the U.S., negative public opinion has been instrumental in keeping GE fish off store shelves. In 2013, a New York Times poll revealed that 75 percent of respondents would not eat GE fish and 93 percent said such foods should be labeled as such.21

The argument for gene-edited foods has been that they’re somehow more natural than GE foods, as they don’t have foreign genes inserted, only tweaks to already existing DNA. But is a meat from a mutant pig with extra muscle and vertebrae really the same as meat from a wild pig?

The U.S. Food and Drug Administration (FDA) proposed to classify animals with edited or engineered DNA as drugs, prompting backlash from the biotech industry,22 but the fact remains that we're dealing with a whole new world when it comes to food from gene-edited animals — and consumers deserve to know what they're eating.

Only then can you make an informed decision about whether or not to consume gene-edited or GE foods. Without a label, however, if such foods come to the market they'll blend right into the food chain with unknown consequences, just as has been done with GMOs in the past.

Further, since the genetic alterations are permanent and capable of being passed on to new generations, the technology has lasting ramifications for the environment and the natural world should the altered traits enter surrounding ecosystems. While such advancements in technology will undoubtedly be explored, it should be done with an abundance of caution and full disclosure to consumers.