The good, the bad, and the ugly of CRISPR gene editing

Picture of Richard van Hooijdonk
Richard van Hooijdonk
  • A WHO committee wants to create a global gene editing registry
  • UNC scientists used CRISPR to treat a rare genetic disorder
  • A combination of CRISPR and a new drug therapy eliminated the HIV virus from mice
  • CRISPR could have a profound impact on the food we eat
  • Safety and ethical concerns

Gene editing has been one of the most widely discussed, as well as one of the most controversial topics in the scientific community in the last couple of years. It involves using a powerful gene editing tool called CRISPR to remove unwanted genes from DNA or insert new ones to modify the function or activity of a particular DNA sequence. CRISPR gene editing has a wide variety of potential applications in many different fields, including eradicating genetic diseases, developing new antibiotics and antivirals, and creating tastier, more resilient crops.

According to a recent report published by MarketsandMarkets, the value of the CRISPR technology market is predicted to grow from $562 million in 2018 to $1.7 billion in 2023. This upcoming market growth will be driven by several major factors, including recent technological advancements, increased government and private funding, new applications of CRISPR, growing need for advanced therapies for a wide variety of diseases, and a more favourable regulatory environment.

 A horizontal bar graph showing the estimated value of the global CRISPR technology market in 2018, and its predicted value in 2023.

A WHO committee wants to create a global gene editing registry

While a number of scientists around the world have called for a total ban on gene editing in humans, the World Health Organization (WHO) has taken a slightly more positive stance towards the subject. An advisory committee to the WHO recently got together to review the current state of gene editing research and technology and offer suggestions on how to proceed forward.

Rather than banning the technology outright, the committee is advocating for the creation of a global registry that will keep track of all gene editing work in humans, which should help bring more transparency and responsibility to the field. The committee will continue monitoring the situation over the next two years and start working on developing an international framework for the regulation of gene editing research. “Gene editing holds incredible promise for health, but it also poses some risks, both ethically and medically,” says Tedros Adhanom Ghebreyesus, the director-general of the WHO.

UNC scientists used CRISPR to treat a rare genetic disorder

Researchers at the University of North Carolina at Chapel Hill (UNC) recently announced that they’re on the verge of discovering a cure for Angelman syndrome, a genetic disorder characterised by developmental delay, seizures, and speech impairment. Those affected by this condition have a mutated copy of a gene called UBE3A inherited from their mother, while the paternal copy is usually silent. The UNC researchers have now devised a treatment that involves using the gene-editing enzyme CRISPR-CAS9 to unsilence the paternal copy of the gene and restore its neural activity. However, for the treatment to work, the enzyme needs to be injected directly into a developing fetal brain, which raises numerous ethical concerns.

“The earlier you put the genes back and try to fix the problem, the better the therapeutic benefit will be,” says Mark Zylka, the director of the Neuroscience Center at UNC. The treatment has already been successfully tested on mice and cultured human neurons, and Zylka hopes human trials could follow in three to four years. What makes this work particularly important is that it offers hope for the development of treatments for other genetic conditions as well. However, not everyone is convinced this is a good idea. “The idea that you could treat a fetus with [an enzyme] is just a very uncharted area, and there could contain a lot of risks,” says David Segal, a professor of chemistry at the University of California, Davis. “We need to move with caution.”

A combination of CRISPR and a new drug therapy eliminated the HIV virus from mice

A positive HIV diagnosis used to be considered a death sentence, but that’s changed over the years. Thanks to advances in modern medicine and the development of new HIV treatments, the condition has become much easier to manage, allowing those affected by it to live long and healthy lives. However, throughout that time, there’s still one thing scientists have never been able to do – find a cure. Until now.

Researchers at Temple University’s School of Medicine recently announced they were able to permanently remove the HIV virus from the genome of living animals using a combination of the CRISPR-CAS9 gene editing tool and a new antiretroviral therapy (ART) called LASER ART. The researchers tested the treatment on mice, first using LASER ART therapy to reduce the virus to very low levels, and then cutting away the relevant DNA sequences from the infected cells with CRISPR. When they examined the animals later, the researchers could find no trace of the HIV virus in about one third of the mice.

“The big message of this work is that it takes both CRISPR-Cas9 and virus suppression through a method such as LASER ART, administered together, to produce a cure for HIV infection,” says Dr. Kamel Khalili, a senior investigator on the study. “We now have a clear path to move ahead to trials in non-human primates and possibly clinical trials in human patients within the year.”

https://www.youtube.com/watch?v=cAOCGk42_6I

CRISPR could have a profound impact on the food we eat

As mentioned earlier, CRISPR could have useful applications that extend beyond treating various human diseases, and some of these are expected to have a far more immediate impact on our society, such as editing the genes of various crops to make them more nutritious or more resistant to pests and inclement weather. “I think in the next five years the most profound thing we’ll see in terms of Crispr’s effects on people’s everyday lives will be in the agricultural sector,” says Jennifer Doudna, a geneticist at the University of California Berkeley and co-inventor of CRISPR.

Researchers have already used CRISPR to modify the genomes of various organisms, creating mushrooms that don’t brown, corn that produces better yields, wheat that contains less gluten, and soybean oil that doesn’t contain trans fats. Furthermore, a number of startups in Silicon Valley are currently exploring the idea of using the gene editing tool to produce lab-grown meat. While none of these have been made available to consumers just yet, it could happen as soon as 2020, when the first CRISPRed foods are expected to hit the shelves.

This development is even more likely in the light of a recent statement issued by the US Department of Agriculture (USDA), which said that gene-edited crops with genetic changes that could have been produced with conventional breeding techniques wouldn’t be subject to regulation. Gene editing differs from genetic modification in that it doesn’t introduce genes from foreign species but simply removes genes or copies sequences from similar species, which can also be done with conventional breeding. “This is a tool that creates what nature could create on its own just never got around [to] or had the opportunity to create,” says Zachary Lippman, an expert in the genetics of flowering plants. In the EU, however, gene-edited crops will have a much more difficult road to reach the market, as they’ll be subject to the same stringent regulations as GMOs.

Safety and ethical concerns

As with any other transformative technology that came before it, the use of CRISPR raises numerous safety and ethical concerns. The biggest concern associated with CRISPR is that it could have unintended consequences, inadvertently cutting out large sections of DNA away from the target site and endangering human health. In fact, several recent studies have shown that using CRISPR to edit the human genome could potentially cause cancer. That’s particularly troubling in the case of human germline editing, in which there’s a risk that the genetic changes could be passed down to future generations. Some have also expressed concerns that CRISPR could be used to create ‘designer babies’ with enhanced physical features, intelligence, or athleticism.

Gene editing has been the subject of a heated debate for quite some time now, and judging by some of the recent developments, the argument is unlikely to die down anytime soon. There’s no doubt that gene editing could provide numerous benefits for our society, helping us develop new treatments for a wide variety of diseases and bring an end to some rare genetic disorders. It could also help us create healthier plants that produce better yields and are better equipped to handle the ravages of climate change. On the other hand, some of the concerns mentioned by the technology’s detractors are more than justified, most notably the risks to human health. The truth is that we simply don’t know enough about how CRISPR works or what the possible side effects might be, so we need to proceed with caution, especially when it comes to human testing.

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