Why Are Scientists So Upset About the First Crispr Babies?

Dec 05, 2018 · 55 comments
Edwin Jaufmann Jr (Indio, CA, USA)
The concern for the world is the start of direct contamination of the human gene pool. Don’t rise up just yet, I’m not speaking about eugenics. Many diseases already contaminate the gene pool. I’m speaking about something far more dangerous. We have crossed the line into direct editing of the genome. Doing this directly can introduce variations far more dangerous to humanity, reproduction and survivability of the species, that hiv, Ebola or any other virus one could imagine. A change to the genome and that change’s propagation throughout humanity might not have a repercussion immediately, but could mean the eventual ending of humanity. And, as a safety measure do we sterilize these children or place them in quarantine? I would not want to be the person or group weighing containment of the contamination against the human rights of innocent children. This is a horror story from all angles and views.
Majorteddy (Midland, Mi.)
I am surprise3d than China has not put the smack down on this doctor.
wilhelmsen (<br/>)
Will the children be told what was done to them? If they are not then they will have been deeply, tragically deceived. This is shockingly callous. If they are told, and nature attempts to restore proper order with disease, how do you think they will feel about that? Highly tragic, and completely unnecessary and arrogant.
GvN (Long Island, NY)
I'm not claiming a solution, nor an ethical opinion. However, it is just wishful thinking that the Crispr genie can be put back in the bottle. Someone, somewhere, sometime will start editing the human genome. All the information and materials are readily available. Nuclear proliferation can be monitored by tracking nuclear material. This is not possible for genetic editing. Be prepared for some 'interesting' humans to appear soon.
richguy (t)
Acromegaly nation. Look forward to pre-nups and divorces involving gene editing of offspring. Mothers will demand sons who are 6' 5". My experience informs me that women are far more concerned about the genetic composition of their children than men/fathers are. People already seek out specific physical and mental traits (and medical history) in a prospective mate. Therefore, gene editing is already happening at speed dating events. But I foresee divorces due to disagreement about the eye color of the kids. Couples already argue about furniture. The mom wants kids with green eyes. The father wants to leave eye color up to chance. There will be debate about who has more ownership over a fetus, the mother or the father. Say goodbye to curly hair. Anybody under 6' 2" and anybody with a receding hairline will be deemed Crispoor, because their parents were too poor to Crispr them properly.
Bridgman (Devon, Pa.)
There's lots wrong with Dr. He's methods and means, but engineering humans is something we should be doing. About 70,000 homo sapiens got smart and beat out the other human species. Neanderthals had larger brains than we do but they weren't wired as well. Someone is going to engineer humans to be many times smarter than we are now and those people will out compete everyone else. The race is on.
Jack (Boston, MA)
If there is a technical way to do it....it will be done. Someone is always willing to step over the line in the search for knowledge, fame, or gain. Get ready for 6'6" blond aryans with Nobels, Pulitzers, and Oscars cluttering up their rooms. I for one welcome our new overlords.
Gregory Scott (LaLa Land)
I have what I suspect is a fairly unorthodox view of this issue: unless and until we are willing to, and then actually do, regulate who is allowed to have children and why, any purported moral or ethical concerns about the impact of embryonic research on the health, welfare, and physical and mental well-being of the resulting children that are born seems… misplaced and myopic at best, hypocritical and destructive at worst. Every day, all day, we have children conceived by, gestated by, and born to addicted, abusive, morally bankrupt, and/or emotionally crippled people who have absolutely no skills or capacity for raising functional, healthy human beings. Yet in 100% of these cases, the reproductive freedoms of the parents to engage in their genetic experiments are the only cultural and legal considerations, there are absolutely no meaningful conversations around the ethics or rightness of that social construct for any of those yet-to-be-born children. In the face of that reality, the “outrage” and “disgust” of the scientific community, or anybody else for that matter, towards this particular strain of genetic research strikes me as cognitive dissonance on an epic scale.
Jay (Yokosuka, Japan)
Those babies could have health complications because of the editing. They could have birth defects. It's very very very interesting that they are able edit human genes... but it is still monstrous.
SR (Bronx, NY)
If it were *just* about how to help the infertile who (for some bizarre reason, under "covfefe" AND the ongoing climate attack) want children, or to correct horrible diseases, and if our health system was non-crazy, it would be tolerable. But none of those are even close to the case. Dr. He stealthily and recklessly did this work. xi China is well-known for its...selective breeding practices and community "harmony" (read: government tyranny) at personal freedoms' and rights' expense, and their healthcare regime combines shady traditional cures with shady modern wallet-pilfering drugs, scalped appointment tickets, and "black ambulances" on a veneer of a single-payer-ish system. Here, we have our own racist who's seized our helm and would LOVE to use this to Make America White Again, and our wildly unequal healthcare is famously almost as much laughingstock as him at a UN General Assembly. In both cases this will only mostly benefit those who can already pay for drugs and still have enough to bribe the doctor—even if prices fall and don't get Shkreli'd or Bresched—and won't help us have LESS children instead of MORE to prevent climate overload and resource overuse. We'll eat and heat ourselves out of house and home, out of world and Earth! Zimmer[1] says we should be less paranoid. I think we're not paranoid enough. I vote Ban Entirely, at LEAST until xi and the miniputins go. [1] https://www.nytimes.com/2018/12/01/sunday-review/crispr-china-babies-gene-editing.html
Albert Ross (Alamosa, CO)
I'm reading "Brave New World" for the first time and this news is the first thing capable of interrupting my reveries about how boring it is to read books.
Melissa (Massachusetts)
I think we need to ask: When is it morally OK to intervene to deal with a medical condition? How can we realistically say intervening at the embryo stage is wrong, while intervening with therapies at age 2, 20, or 60 is fine? Do we really think there is a moral justification for holding off with an embryo, only to spend more later to treat something that could have been corrected pre-birth? Why is it more "moral" to wait until birth? Also, it's interesting that resistance is coming from the Christian right... I thought they believed in "personhood" from egg fertilization?
Damri (Fort Worth)
It was bound to happen sooner or later. Moral compasses never outweigh large benefits especially when the promise is of human evolution and better lives. While the goal is lofty to address untreatable and severe diseases, fundamentally it goes against natural selection when we have put human long and disease free lives ahead of every other species, unless we apply moral compass to only humans. I don't think we will have the same outcry if this was done on animals where we solved a food problem. Where do you really draw the line - If someone offers a life changing solution for their future generations, would people really not consider? Its one thing for scientists to talk about moral compasses in a scientific convention, its another thing to prevent people to say no to suffering families who look at this as their only hope for a better future. Mistakes and stumbles will be made but inevitably gene editing will be done for humans - Its just a question of when it will happen. The sooner people accept it the better. The benefits are just too big and far-reaching to say no.
barbara jackson (adrian mi)
@Damri I'm afraid the "benefits" are going to be an overcrowded world of people who will never die without the aid of a pistol - which will be the only way off the planet in the future. At age 80 I see this as a spectacular downer. We seem to see the spectrum of life differently depending on what we're looking at. Religion tells us that all life is sacred so therefore, we must allow every throbbing (human only, please) glob of cells to survive even when they are whispering of a different fate. But man has the last word, and he translates God's word as he sees fit. But the planet, in the end, is really going to have the last word.
David (Michigan, USA)
If it can be done, someone is going to do it. Unavoidable. This technique could be used to help deal with autoimmune diseases and other genetic problems that are very difficult to deal with after someone has advanced beyond the embryo stage. Not clear exactly how the safety of the procedure will be established unless someone tries it. Could be done in animals first but translating results to humans is never a certainty.
Jay (Yokosuka, Japan)
@David I'm more concerned about the fact that this is germline editing. The edited trait will pass on to future generations, whether or not that trait is good or bad.
carla (ames ia)
Thank you for this article. To complete the story on CRISPR-Cas9, please follow it up with all the research on animals going on now that IS funded by the NIH. Let's have the full picture of what is being done with this technology, and the risks as well as potential benefits. I am on the biosafety review committee at a major R01 research university and there are lot of questions about this technology that still need to be answered.
Edwin Jaufmann Jr (Indio, CA, USA)
As much as PETA may disagree with me, animal research does not pose the risk to humanity that human genome editing does. Experimental animals are euthanized, not released to propitiate their changes into the genome of their species.
Renaud (California USA)
Let it begin! It is an imperative. We improved: apples, grains, peas, rice, cows, sheep, ..on and on. Why not improve the human species? It is fear, fear of the unknown, fear of ..whatever. You, me, everyone alive today is a product of random genetic mergers. Once a crspir can remove and improve human beings, being a human is a better deal. and, no one can stop it. Ban it in the US and the Chinese will run with it. All us Humans 1.01 have to let human(s) 1.02 begin, let the race begin! I'm all for it!
barbara jackson (adrian mi)
@Renaud If they can edit out the kind of immorality that has blessed us with the political mess we are now in, I'd be all for it . . .
lelectra (NYC)
@Renaud "We improved: apples, grains, peas, rice, cows, sheep, ..on and on" Did we? Improve them? In what way?
Slann (CA)
I'm betting Dr. He has a FB page. I'm also betting China has done MANY gene splicing experiments on humans, especially with the goal of producing superior athletes, which is a logical progression of the work they have been doing for at least 20 years. Genetic manipulation cannot be recognized by test techniques, as can substance use. They would not want a self-aggrandizing social media-infected doc to pull the spotlight to an area they would prefer remain in shadows.
Chris (<br/>)
So much is unknown, no peer review, no real data. Ethically, however, if this was done to normal embryos (and what is a "normal" embryo, what tests were run to confirm normal), this is unconscionable. And how shortsighted can a scientist be? Knocking out a single gene seems so innocuous except for the fact that the protein was there for a reason, otherwise it wouldn't have been retained and conserved. A brief look at the literature indicates the gene may also be important in granulocytic lineage proliferation and differentiation. That means not having this gene could potentially dampen the generation of the types of cells involved in the immune system. It also has other ligands, one of which, CCL5, is responsible for the recruitment of immune cells in the event of an acute infection. These twins could be immunocompromised in ways that are unexpected. That means that overall well being of the offspring played no part in consideration of what the outcome might be. That is unconscionable as well.
Carlos (Seattle)
@Chris The downsides of crippling this gene is more than offset by the benefit of HIV resistance in a country with an HIV epidemic.
RM (Vermont)
Back a couple centuries ago, children born with seriously defective genes were born, but the lack of effective treatments often meant that these children did not survive to reproductive age. So the children died, and their defects died with them. As medicine progressed, children with weak hearts or other vital organs could survive and reproduce. Thereby introducing undesirable genetic traits into the human gene pool. While weakening the gene pool may not have been an intent, it is a defacto result. I think it would be a wonderful thing to build a medically more robust human race by weeding out many common genetic defects. If we strive to eliminate measles and smallpox, is not the elimination of genetically induced serious diseases also a worthy goal for mankind?
David M (Chicago)
@RM. Gene editing cannot eliminate genetic diseases for at least two reasons: 1. Many diseases are caused by new mutations and thus not known until birth. 2. Mutations that cause a recessive diseases will always be present in the population as they are silent. But the easier way to eliminate inherited diseases is to do prenatal genetic screening and/or genetic testing of the parents followed by counseling.
Edwin Jaufmann Jr (Indio, CA, USA)
It’s not what, but how. Right now there are two children, alive, but with an unknown alteration to their genome. Could those changes spawn virus? Could the change be dominant in transmission to their children? What are the full implications of the changes? And will we even know the answer until four, five or five hundred generations in the future? Are these children being contained as to not transmit potential viral generation? Will they be sterilized as not to pass on their modifications? It’s the fact that these two human beings could not give their consent to these gross ( and unnecessary ) modifications to their genome. We have ethics discussions about the right of parents to circumcise male children. We outlaw female circumcision in many countries. But, we allow parents to modify embryonic genomes?
ubique (NY)
It’s just the potential future of the entire species that’s being toyed with. Why all the fuss? This guy has unleashed a bioethical nightmare, whether or not he even performed the procedure. Our collective understanding of the human genome is still not sufficient to be introducing these glorified abominations into the global populace.
George (Atlanta)
Pardon me as I suspend my outrage for just a bit. Without data, peer review, and replication, we don't have science. All we have here is pearl-clutching and an impetuous smart guy who dumped his career (maybe his life, too, as the Chinese authorities are a bit miffed) down the toilet. Big picture, and beyond this particular transgression, CRISPR is widely understood and currently being used in research. I understand the risk of this to a germline, and it's a bad thing and all, but all those 'ethical norms and guidelines' counted for zilch here... and the 10 other places in the world where this is certainly being pursued right now. We won't be able to unring this bell.
4Average Joe (usa)
The germ line is Sacred, and not wholly understood. Crispr is cheap, a few HUNDRED DOLLARS, available on line to everybody. God Help us.
R.G. Frano (NY, NY)
Instead, Dr. He went ahead and disabled a perfectly normal gene, CCR₅. While people who are born with both copies of CCR₅ disabled are resistant to H.I.V., they are more susceptible to West Nile virus and Japanese encephalitis. And there are simpler and safer ways to prevent H.I.V. infection..." Humanity STILL measures hominid-starvation in the 10's/1,000's per day, so... Why the experimental_haste, as evidenced by creating these creatures?? If these two pregnancies actually exist / are allowed to birth...they will pass along their genes, including defects, (if any...), modifications, (if any...), and ANY/ALL 'conditions', 'not imagined before the fact', re any children, created... What if there exists some issue / circumstance which creates deformities / defects...several generations, hence? And...how would Dr. He / anyone be able to predict/ manage such concerns??!!
Charles K. (NYC)
@R.G. Frano I'm glad to see someone acknowledging those other extant hominids (bigfoot?).
STONEZEN (ERIE PA)
@R.G. Frano While we are concerned that people will be adversely affected I think we are even more concerned that some kids my have some advantage that others do not have. It seems not fair that someone's lineage could be better then everyone else in that generation and future generations. We are not worried about defects and this experimentation will continue. In some ways this is another RANDOM mutation exept caused by people so let's stop pretending we are concerned with hurting people.
David Konerding (San Mateo)
I'm a scientist. 30 years ago I learned about gene modification and made gene therapy my field of interest. I spend about 20 years pursuing it only to conclude that it was really premature to consider germline modification but that I trusted a limited group of academics at well-established institutions to duly consider the challenge and address it responsibly, transparently, and with respect. The reason I'm annoyed is that by doing this, Dr He has basically prevented those more responsible people from moving forward. Now more people will die and suffer because of his thoughtless actions. What is truly amazing is his total lack of awareness that in announcing this, he would end up causing the problems that he did. It's like he never grew a moral compass.
John (NYC)
And so we continue on the never ending path of self-domestication. The human beings of our era may be looked back upon by those in the future as the last "wild men;" who let Mother Nature alonw decide and determine their physical fates. But I have to wonder. I look around and all I see done by our hand is mono-culture. In our striving for a self-defined perfection we create one genetic strain of apple, of corn, of anything we domestic on an industrial scale. Are we wise enough to understand the danger we may be putting ourselves in? Look at all the fantastic diversity of the living web of life that is enmeshed on our planet. We, our scientists, should be looking most closely at why it is Mother doesn't "do" mono-cultures....we should not seek this for ourselves. And it is my fear that in our striving for our view of (our own) perfection this is what we will do to ourselves. So it may go. John~ American Net'Zen
Thomas (Maryland)
There is already a popular majority to allow genetic editing to 'fix' the most severe, and well researched, genetic mutations that cause the most debilitating diseases. Those who ask about the consent of the unborn should be equally concerned about the consent of babies born with such conditions if the manifestation of the mutation was avoidable. We are now at a point where genetic risk can be assessed pre-conception, and, importantly, pre-implantation of the fertilized egg/zygote. I find it entirely acceptable to make a pre-implantation selection if a well-defined genetic risk is present. Regarding the risk of introducing genetic changes that would affect future generations - that happens at every conception randomly, and uncontrolled. Ethically, the step from pre-implantation diagnostics to Dr. He's edit is not that large, and I am glad that he did it, given the professional risk. It is unfortunate that China is the only place where this is now possible, not for scientific reasons but for political ones.
Mike (near Chicago)
Yes, there are likely to be strong arguments in favor of some particular changes to the genome. That doesn't mean that those arguments apply to every possible change. This change in particular seems unjustifiable, given that the change that He tried to introduce has, even in the ideal case, negative effects as well as positive ones. Moreover, if you are willing to condone this sort of experimentation in human children, you certainly can't object to doing the same kind of work in shorter-lived animals like mice that will reveal if the edit has worked as planned. This particular experiment appears to be premature, ill-thought out, and done without any concern for even the most basic ethical safeguards, such as proper consent from the parents. Even if you're for gene editing, you shouldn't be in favor of foolish botches like this.
David Siegel (On the N Judah)
Thank you for this writeup. Aside from every other moral and ethical concern... I just don’t see how it’s possible that the parents could have given informed consent.
Linda (<br/>)
This guy is a fraud. Science is not conducted via YouTube. The fact that he refuses to publish his data and have it evaluated by the normal route of peer review is a huge red flag. Who cares that he has a PhD from a reputable university, he's a sham and disgrace as a scientist.
Charles K. (NYC)
@Linda I have a feeling that he might be in the same league as the Raelians who announced the first cloned human beings over a decade ago but didn't show any evidence out of "concern for the parents' privacy." Or maybe those guys who claimed to generate pluripotent stem cells by adding a bit of salt to some differentiated cells.
Greg (Brooklyn)
"Some worry that this is the first step toward using gene editing to create people with extreme intelligence, beauty or athletic ability. " And some of us hope it is the first step. Clearly this is the next step in human evolution, whether anyone likes it or not.
Slann (CA)
@Greg "Clearly this is the next step in human evolution," Nonsense. That's not clear at all. Eugenics was "all the rage" in the early 20th century, and the goal was the same. There was this guy from Germany who became a fan....
John McDavid (Nevada)
Since we discard embryos without a second thought, the first step won't be CRISPR. It will be to fertilize hundreds of embryos, test their DNA, and choose the best of the lot. It's just a matter of mapping genes until this starts happening - 23 & me, but in full fidelity before uterine implantation.
Zoë (NYC)
@Greg You think you want that, but you don't. I don't want it to be the first step because history has shown that when put to moral tests, we fail every single time. It would only be a human "evolution" for the elite rich few who can afford the genome editing. It will end up placing the rich above the everyday person, and weed out any chance that everyday people can compete for jobs, resources, or whatever other human need there is. That is not human evolution, it's plutocratic evolution of the worst kind that will only widen the gap permanently between the haves and have-nots. I assure you, you don't want a world where the rich are genetically altered to rule and stay as rulers for generations to come.
Pete Rogan (Royal Oak, Michigan)
The prospect of disruption and confusion in the wake of Dr. He's experiment now takes shape. Ethical questions about the health of the affected, including the consent of the unborn, are now crowded by political questions of the necessity or desirability of such experiments compared to the damage done by NOT experimenting. And all of this falls under the mantle of how we define 'better' and whether we can actually make such decisions better than Nature can. The can of worms has been opened, and it was under pressure. Debates will now rage that will not be settled by further experimentation or the results. We have a claim of gene editing and its benefits; all else that will be attempted, studied or just observed from this point forward will be with the knowledge that human beings can now intervene in the process. The end is less important than the means. I expect to see more experimentation, particularly by those on the fringe of the present medical establishment and perhaps in open defiance of their ethos. I expect damage to be done. I expect the question will not be resolved, but only further muddied as even normal research is colored by Dr. He's experiment. Regeneration of liver cells? Genetic restructuring of the placenta? Eye implants to restore or improve vision, for the impaired or non-impaired? All will be questioned and their objectives scrutinized in the new political reality of possible human gene editing. We are not going to like the results.
htg (Midwest)
We've been doing this with corn for decades. What's the problem? /sarcasm.
Nasty Kornstalk from (Kornfeld, Calif.)
Yeah, right arm, branch, leaf (or whatever you got)! I came out of a test tube, and I’m just fine (Except I am being raised organically, by a bunch of pot smoking he peas — usually the male of that species, but sometimes I’m confused because their dreadlocks always get tangled in my stalks and flowing blonde cornsilk). I got to go now, I see someone coming with a scythe that’s going to cut me down and harvecide me! Well, At least it’s not the old international Harvester Combine & thrashing treatment , and it’s just a hippy or a homey (not sure which, they both need money: the hippie use it to buy more pot, the homey uses it to buy more booze)
Robert M. Koretsky (Portland, OR)
In plain words, what is called a “gene”, and the making of all of the proteins by that gene, have not been totally defined yet. So what this man did, aside from introducing the mosaic effect, is bring a possibly large error into the making of proteins by the human genome. Not sci fi dystopian fiction, a real world mistake that probably will lead to all kinds of catastrophic diseases. Instead of waiting until a complete system of information and knowledge about what the “gene” he fooled around with exists, he did this for fame and fortune now. Talk about a crime against humanity!
Anym (HK)
Just because we can achieve certain goals does not mean we should. The human genome is web of vastly complicated and intractely tied connections. To attempt at re-designing, or interfering with that web is at best a display of good intentions, at worst hubris. To truly know the effects of this gentic alteration of the twins would require observation. Are they truly immune to HIV? Has the alteration made them mor suspectible to other diseases? What are the side effects? The answer is we don't know. That is the danger behind this attempt. It is to fundamentally alter the blueprint (however small piece of it that was altered) of two hman beings, without knowing absolutely what the potential unintended effects may be. It is to say, well, humanity needed to proceed to the next stage of evolution. Thus, you two, have been thrusted onto the stage as the first guinea pigs for that endavor. There is a reason why, when scientific breakthroughs were hurridley rushed to human applications without further thought tend to bring about negative unintended consequences. For example, there were the chemicals discovered and then widely applied for airconditioning. Yet, it was later discovered to act as an agent which decreased the strength of the ozone layers of the atmosphere. When the full and complete effects of new scientific breakthrough are not fully understood, the risks of applying it becomes exponentially increased.
TFD (Brooklyn)
The cat is officially out of the bag. Now we must wait for the fallout then create specific regulations to combat/mitigate the worst of it. Heaven help us.
Dwight Jones (@humanism)
The imminence of human cloning colors academic press accounts of biotechnology directly related to reproduction. Ever since the Dolly the Sheep became the first mammal cloned in 1996, a cultured 'ethical' hysteria has met just about every innovation since. Given two decades of accelerating advances since then, you can fairly believe that cloning without intrusive Crisper/embryo techniques is now readily achievable. The next media feast will accrue around disclosures still sitting in the bush. Ad hoc, self-appointed ethics councils may prove to be no more reliable judges of confessions like Dr. He's than were Inquisition tribunals examining 'witches'. Human reproduction will be fought out between conservative cloning, which recognizes your phenotype (not your brain) as the seat of your identity versus Trans-humanism and the evolution of digital intelligence. The unregulated, mind-uploading vista is not worthy of our own legacy, by any standard. Within this high-stakes race against AI and robotics, basic cloning is a conservative option anyone can reserve to carry their own identity into a future we have not yet ceded to some assembling AI entities. So if a couple raises two clones instead of two 50/50 children, perhaps women will be spared the burdens of gestation, and YOU might see the miracle of a fresh life cycle? Do 'ethicists' have some assumed right to proscribe that option, if soon proven reliable? Do researchers in turn have a right to ignore them?
Kevin (Maryland )
It seems like the main concern is the domino effect. Many genes don't affect one attribute but work in concert with other genes. A change in one place might make an improvement in one place but cause problems in another. Of course, this is where science and experimentation provide answers. The thing is, it is one thing to conduct these types of experiments on fruit flies and tomato plants. With humans, scientific knowledge comes at the expense of someone's life and potentially their offspring. Even more so, these are babies who have no say in their decision to be experimented on.
Nasty Curmudgeon from (Boulder Ck. Calif.)
I’m concerned that Mr. He (former title, Dr.) did not choose to alter something more relevant, like the size, or quantity of human sweat glands, to compensate for the impending increases in temperatures but this can be understood, since during his time at university (my old stomping grounds, Stanford U), aids & Human immunodeficiency, was the du jour threat to mankind.
Nasty Curmudgeon from (Boulder Ck. Calif.)
By the way, and just for clarity and UN-bragging rights, I partied at the Stanford campus early on and later worked in the hills above Stanford, the Linear Accelerator Center But these comments, that reek of either a pro life fundamentalist stance or, a dissatisfied legal career, paraphrasing and condensed to: “didn’t the egg-sperm -embryo -fetus - have human right to....” (at least sign a non-disclosure agreement or something a rather) strike me as just some more touchy-feely whining & hem hawing. I say, just ask any “test tube baby” , Even though they were conceived outside the human… Most of them came out just fine.
John Leavitt (Woodstock CT)
This story is reminiscent of of the possible cloning of human beings. The concern was that we don't know if reprogramming of a somatic cell nucleus to the early embryonic program of gene expression is accurate and reproducible to the extent that this program reflects the natural genetic control in a sperm cell and egg after meiosis. The impact of the editing on the pleiotropic effects of the CCR5 protein is another question mark.