Last week, a newly published research paper showed that, for the second time in history, Chinese scientists had genetically modified human embryos. The researchers, led by Dr Yong Fan of the Guangzhou Medical University in China, injected human embryos with the molecular instructions required to build a gene-editing tool. Their aim was to artificially cause a mutation to the CCR5 gene in order to create HIV resistance, and they were partially successful, with four out of 26 embryos showing signs of the mutation.
The controversial experiment has reignited debate within the scientific and broader communities about what limits there should be, if any, to genetic research. Gene editing poses an array of ethical problems and it could radically change our understanding of what it means to be human.
The revolutionary gene-editing tool, also known as CRISPR-Cas9, was discovered in 2012 by Dr Emmanuelle Charpentier, director of the Max Planck Institute for Infection Biology in Berlin and head of the Department of Regulation in Infection Biology at the Helmholtz Centre for Infection Research, and Dr Jennifer Doudna, a molecular biologist from the University of California, Berkeley.
It comprises two components – CRISPR is essentially two short single strands of RNA, a copied form of the double-stranded DNA; and Cas9 is an enzyme that can be directed to “cut” DNA strands at a specific gene location. Cas9 attaches to CRISPR and uses it to locate the sequence of DNA that corresponds with CRISPR’s RNA strands. Once the CRISPR-Cas9 complex arrives at the DNA site, Cas9 acts like a pair of molecular scissors and severs the DNA strand.
Professor Bernie Tuch, director of the NSW Stem Cell Network and honorary professor at the University of Sydney, told The Saturday Paper gene editing was “a very constructive and positive step” in understanding the nature of genetic disorders and communicable diseases.
“It’s a very positive thing in the sense that you can create certain animals with a genetic disorder in order to be able to better understand the nature of the disorder,” Tuch said.
However, he sees the Chinese research as more of a practice run, as the scientists would have been more concerned with fine-tuning their technique rather than achieving a realistic outcome.
“In essence, the people from Guangzhou [Medical University] in China are trying to develop the art of being able to modify genes in embryos,” he said. “They’ve used abnormal embryos in order to practise their technique. They were partly successful, partly not, and they can’t quite control it.”
Professor Ed Stanley, a stem cell researcher from the Murdoch Children’s Research Institute, also questioned the practicality of the research given there are already efficient and cost-effective methods to both treat and manage the spread of HIV.
“Obviously the preventative measures that we have in place in countries like Australia are probably a lot more cost-effective and come with much fewer both ethical and practical implementation issues than going and editing embryos,” Stanley said. “From a practical point of view the value of the research simply shows that people can edit human embryos.”
But if scientists were to take the next logical step, for which many have been arguing, to what extent should gene editing be used in human embryos? Are we ultimately “playing God”?
According to Reverend Professor Andrew Dutney, a theology and bioethics expert at Flinders University, the issue is about how we wield this new power.
“There’s often concern expressed about human beings playing God or scientists playing God,” Dutney said. “In my own view, there’s nothing inherently wrong with playing God, the issue is what kind of God are you playing?”
Professor Dutney argues that the use of ultrasounds to check for physical abnormalities in the foetus and the more recent development of pre-implantation genetic diagnosis (PGD), which works exceptionally well with IVF to identify genetic or chromosomal abnormalities, are essentially tools for selective breeding. The information gathered from these prenatal diagnostic tools can help doctors and parents-to-be decide whether to terminate the pregnancy.
“We don’t assume that we just accept the child that we’re going to get; we do assume that, at some level at least, we have the opportunity to second-guess the suitability of a foetus actually being taken to term and delivered,” he said.
Dr Miles Bore, a senior lecturer in psychology, morality and ethical decision-making at the University of Newcastle, has serious concerns about the application of CRISPR-Cas9 in human embryos and says that, without proper safeguards, there is nothing to stop scientists from trying to “cure” traits that may be deemed by some to be undesirable.
“What if that same technology was used for other things, for ‘curing’ things that while some people might consider a disease, other people and perhaps scientific evidence shows is just normal, natural human variance?” Bore said.
He invokes the principle of the double effect to prove his point: “If you set out to be ethical in what you are doing, if in order to achieve an ethical outcome you have to do something that is unethical, then by logical argument you can’t claim to have been ethical.”
The co-discoverer of CRISPR-Cas9, Emmanuelle Charpentier, has expressed similar concerns about how scientists use her gene-editing technology in human embryonic research, as was revealed in an interview with New Scientist last year.
“I hope that using the technology with the idea of changing human characteristics will not be pursued,” she said. “When it comes to using it for therapeutic and preventative purposes – not to change traits that could be inherited throughout the population – then the debate will be for certain kinds of diseases for which maybe the manipulation of the human germline will be considered.”
However, Ed Stanley thinks this fear that scientists will create “superhumans” is unrealistic and unjustified. “It’s all very well to say we could create a super race by doing gene editing, but in reality none of us would know what that looked like. I think it’s a very unlikely application of the technology.
“What you also have to appreciate is that these new tools aren’t appearing in a vacuum of other technology. There is a lot going on in a whole lot of fields that potentially would circumvent the need for gene editing of embryos in the first place.”
In December last year, scientists, bioethicists and government representative met in Washington, DC, for the International Summit on Human Gene Editing to establish how the world should proceed with gene-editing research. The summit conveners ignored calls for a moratorium on gene editing of human embryos and instead made a series of recommendations that they hope will provide ethical guidelines for researchers.
The Chinese researchers, who had begun their experiment months before the summit, have acknowledged these recommendations and stated: “We believe that any attempt to generate genetically modified humans through modification of early embryos needs to be strictly prohibited until we can resolve both ethical and scientific issues.”
The scientific community is normally quite effective at setting down its own set of rules to guide researchers in their work and to avoid ethical minefields, which is critical, as the law often struggles to keep pace with scientific advances.
“The legal system always lags behind the reality and it takes years of consideration for realistic guidelines to eventually be developed,” Bernie Tuch said. “In the meantime, of course, scientists and ethicists get together and try and manage the situation, and I guess that’s precisely what’s happening at present.”
The committee for the gene-editing summit is expected to hand down a consensus report later this year with more detailed guidelines for research, but until then the great ethical question remains unanswered: do the ends justify the means?
This article was first published in the print edition of The Saturday Paper on April 16, 2016 as "Tailored genes".
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