BIG QUESTION OF THE MONTH: Should we use CRISPR, the new technique that enables precise DNA editing, to change the genes of human embryos to eradicate disease--or even to enhance desirable traits? LeapsMag invited three leading experts to weigh in.
Now that researchers around the world have begun to edit the genes of human embryos with CRISPR, the ethical debate has become more timely than ever: Should this kind of research be on the table or categorically ruled out?
All of us need gene editing to be pursued, and if possible, made safe enough to use in humans. Not only to pave the way for effective procedures on adults, but more importantly, to keep open the possibility of using gene editing to protect embryos from susceptibility to major diseases and to prevent other debilitating genetic conditions from being passed on through them to future generations.
Objections to gene editing in embryos rest on three fallacious arguments:
- Gene editing is wrong because it affects future generations, the argument being that the human germline is sacred and inviolable.
- It constitutes an unknown and therefore unacceptable risk to future generations.
- The inability to obtain the consent of those future generations means we must not use gene editing.
We should be clear that there is no precautionary approach; just as justice delayed is justice denied, so therapy delayed is therapy denied.
Regarding the first point, many objections to germline interventions emphasize that such interventions are objectionable in that they affect "generations down the line". But this is true, not only of all assisted reproductive technologies, but of all reproduction of any kind.
Sexual reproduction would never have been licensed by regulators
As for the second point, every year an estimated 7.9 million children - 6% of total births worldwide - are born with a serious birth defect of genetic or partially genetic origin. Had sexual reproduction been invented by scientists rather than resulting from our evolved biology, it would never have been licensed by regulators - far too inefficient and dangerous!
If the appropriate benchmark for permissible risk of harm to future generations is sexual reproduction, other germline-changing techniques would need to demonstrate severe foreseeable dangers to fail.
Raising the third point in his statement on gene-editing in human embryos, Francis S. Collins, director of the National Institutes of Health, stated: "The strong arguments against engaging in this activity remain … These include the serious and unquantifiable safety issues, ethical issues presented by altering the germline in a way that affects the next generation without their consent."
"Serious and unquantifiable" safety issues feature in all new technologies but consent is simply irrelevant for the simple and sufficient reason that there are no relevant people in existence capable of either giving or withholding consent to these sorts of changes in their own germline.
We all have to make decisions for future people without considering their inevitably absent consent. All would-be/might-be parents make numerous decisions about issues that might affect their future children. They do this all the time without thinking about consent of the children.
George Bernard Shaw and Isadora Duncan were possibly apocryphal exceptions. She, apparently, said to him something like: "Why don't we have a child? With my looks and your brains it cannot fail," and received Shaw's more rational assessment: "Yes, but what if it has my looks and your brains?"
If there is a discernible duty here, it is surely to try to create the best possible child, a child who will be the healthiest, most intelligent and most resilient to disease reasonably possible given the parents' other priorities. This is why we educate and vaccinate our children and give them a good diet if we can. That is what it is to act for the best, all things considered. This we have moral reasons to do; but they are not necessarily overriding reasons.
"There is no morally significant line between therapy and enhancement."
There is no morally significant line that can be drawn between therapy and enhancement. As I write these words in my London apartment, I am bathed in synthetic sunshine, one of the oldest and most amazing enhancement technologies. Before its invention, our ancestors had to rest or hide in the dark. With the advent of synthetic sunshine--firelight, candlelight, lamplight and electric light--we could work and play as long as we wished.Steven Hawking initially predicted that we might have about 7.6 billion years to go before the Earth gives up on us; he recently revised his position in relation to the Earth's continuing habitability as opposed to its physical survival: "We must also continue to go into space for the future of humanity," he said recently. "I don't think we will survive another thousand years without escaping beyond our fragile planet."
We will at some point have to escape both beyond our fragile planet and our fragile nature. One way to enhance our capacity to do both these things is by improving on human nature where we can do so in ways that are "safe enough." What we all have an inescapable moral duty to do is to continue with scientific investigation of gene editing techniques to the point at which we can make a rational choice. We must certainly not stop now.
At the end of a 2015 summit where I spoke about this issue, the renowned Harvard geneticist George Church noted that gene editing "opens up the possibility of not just transplantation from pigs to humans but the whole idea that a pig organ is perfectible…Gene editing could ensure the organs are very clean, available on demand and healthy, so they could be superior to human donor organs."
"We know for sure that in the future there will be no more human beings and no more planet Earth."
We know for sure that in the future there will be no more human beings and no more planet Earth. Either we will have been wiped out by our own foolishness or by brute forces of nature, or we will have further evolved by a process more rational and much quicker than Darwinian evolution--a process I described in my book Enhancing Evolution. Even more certain is that there will be no more planet Earth. Our sun will die, and with it, all possibility of life on this planet.As I say in my recent book How to Be Good:
By the time this happens, we may hope that our better evolved successors will have developed the science and the technology needed to survive and to enable us (them) to find and colonize another planet or perhaps even to build another planet; and in the meanwhile, to cope better with the problems presented by living on this planet.
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on scientific creativity and progress to give you a therapeutic dose of inspiration headed into the weekend.
Here are the promising studies covered in this week's Friday Five:
- How to improve your working memory
- A plain old solution to stress
- Progress on a deadly cancer for first time since 1995*
- Rise of the robot surgeon
- Tomato brain power
And in an honorable mention this week, new research on the gut connection to better brain health after strokes.
* The methodology for this study has come under scrutiny here.
Elaine Kamil had just returned home after a few days of business meetings in 2013 when she started having chest pains. At first Kamil, then 66, wasn't worried—she had had some chest pain before and recently went to a cardiologist to do a stress test, which was normal.
"I can't be having a heart attack because I just got checked," she thought, attributing the discomfort to stress and high demands of her job. A pediatric nephrologist at Cedars-Sinai Hospital in Los Angeles, she takes care of critically ill children who are on dialysis or are kidney transplant patients. Supporting families through difficult times and answering calls at odd hours is part of her daily routine, and often leaves her exhausted.
She figured the pain would go away. But instead, it intensified that night. Kamil's husband drove her to the Cedars-Sinai hospital, where she was admitted to the coronary care unit. It turned out she wasn't having a heart attack after all. Instead, she was diagnosed with a much less common but nonetheless dangerous heart condition called takotsubo syndrome, or broken heart syndrome.
A heart attack happens when blood flow to the heart is obstructed—such as when an artery is blocked—causing heart muscle tissue to die. In takotsubo syndrome, the blood flow isn't blocked, but the heart doesn't pump it properly. The heart changes its shape and starts to resemble a Japanese fishing device called tako-tsubo, a clay pot with a wider body and narrower mouth, used to catch octopus.
"The heart muscle is stunned and doesn't function properly anywhere from three days to three weeks," explains Noel Bairey Merz, the cardiologist at Cedar Sinai who Kamil went to see after she was discharged.
"The heart muscle is stunned and doesn't function properly anywhere from three days to three weeks."
But even though the heart isn't permanently damaged, mortality rates due to takotsubo syndrome are comparable to those of a heart attack, Merz notes—about 4-5 percent of patients die from the attack, and 20 percent within the next five years. "It's as bad as a heart attack," Merz says—only it's much less known, even to doctors. The condition affects only about 1 percent of people, and there are around 15,000 new cases annually. It's diagnosed using a cardiac ventriculogram, an imaging test that allows doctors to see how the heart pumps blood.
Scientists don't fully understand what causes Takotsubo syndrome, but it usually occurs after extreme emotional or physical stress. Doctors think it's triggered by a so-called catecholamine storm, a phenomenon in which the body releases too much catecholamines—hormones involved in the fight-or-flight response. Evolutionarily, when early humans lived in savannas or forests and had to either fight off predators or flee from them, these hormones gave our ancestors the needed strength and stamina to take either action. Released by nerve endings and by the adrenal glands that sit on top of the kidneys, these hormones still flood our bodies in moments of stress, but an overabundance of them could sometimes be damaging.
A study by scientists at Harvard Medical School linked increased risk of takotsubo to higher activity in the amygdala, a brain region responsible for emotions that's involved in responses to stress. The scientists believe that chronic stress makes people more susceptible to the syndrome. Notably, one small study suggested that the number of Takotsubo cases increased during the COVID-19 pandemic.
There are no specific drugs to treat takotsubo, so doctors rely on supportive therapies, which include medications typically used for high blood pressure and heart failure. In most cases, the heart returns to its normal shape within a few weeks. "It's a spontaneous recovery—the catecholamine storm is resolved, the injury trigger is removed and the heart heals itself because our bodies have an amazing healing capacity," Merz says. It also helps that tissues remain intact. 'The heart cells don't die, they just aren't functioning properly for some time."
That's the good news. The bad news is that takotsubo is likely to strike again—in 5-20 percent of patients the condition comes back, sometimes more severe than before.
That's exactly what happened to Kamil. After getting her diagnosis in 2013, she realized that she actually had a previous takotsubo episode. In 2010, she experienced similar symptoms after her son died. "The night after he died, I was having severe chest pain at night, but I was too overwhelmed with grief to do anything about it," she recalls. After a while, the pain subsided and didn't return until three years later.
For weeks after her second attack, she felt exhausted, listless and anxious. "You lose confidence in your body," she says. "You have these little twinges on your chest, or if you start having arrhythmia, and you wonder if this is another episode coming up. It's really unnerving because you don't know how to read these cues." And that's very typical, Merz says. Even when the heart muscle appears to recover, patients don't return to normal right away. They have shortens of breath, they can't exercise, and they stay anxious and worried for a while.
Women over the age of 50 are diagnosed with takotsubo more often than other demographics. However, it happens in men too, although it typically strikes after physical stress, such as a triathlon or an exhausting day of cycling. Young people can also get takotsubo. Older patients are hospitalized more often, but younger people tend to have more severe complications. It could be because an older person may go for a jog while younger one may run a marathon, which would take a stronger toll on the body of a person who's predisposed to the condition.
Notably, the emotional stressors don't always have to be negative—the heart muscle can get out of shape from good emotions, too. "There have been case reports of takotsubo at weddings," Merz says. Moreover, one out of three or four takotsubo patients experience no apparent stress, she adds. "So it could be that it's not so much the catecholamine storm itself, but the body's reaction to it—the physiological reaction deeply embedded into out physiology," she explains.
Merz and her team are working to understand what makes people predisposed to takotsubo. They think a person's genetics play a role, but they haven't yet pinpointed genes that seem to be responsible. Genes code for proteins, which affect how the body metabolizes various compounds, which, in turn, affect the body's response to stress. Pinning down the protein involved in takotsubo susceptibility would allow doctors to develop screening tests and identify those prone to severe repeating attacks. It will also help develop medications that can either prevent it or treat it better than just waiting for the body to heal itself.
Researchers at the Imperial College London found that elevated levels of certain types of microRNAs—molecules involved in protein production—increase the chances of developing takotsubo.
In one study, researchers tried treating takotsubo in mice with a drug called suberanilohydroxamic acid, or SAHA, typically used for cancer treatment. The drug improved cardiac health and reversed the broken heart in rodents. It remains to be seen if the drug would have a similar effect on humans. But identifying a drug that shows promise is progress, Merz says. "I'm glad that there's research in this area."
This article was originally published by Leaps.org on July 28, 2021.