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The startling announcement by He Jiankui almost one year ago that he had created the first genetically modified human beings unleashed a torrent of criticism. It also brought to the surface common misunderstandings — even among scientists and ethicists — that reproductive uses of this genome-modifying tool have therapeutic value, will treat people with genetic disorders, will save lives, and will eradicate disease. None of those are true.

The twin girls that He helped create are publicly known as Lulu and Nana. Their father is HIV-positive. The scientist said he used CRISPR-Cas9 genome editing technology to disable a gene called CCR5 to mimic a naturally occurring gene deletion that appears to confer immunity against HIV.


A major criticism from the scientific community, which has otherwise been generally supportive of advancing gene technologies, was that He did not use the technology to address a serious medical need. That criterion stems from a 2017 report by the U.S. National Academy of Sciences and the National Academy of Medicine recommending that, once the technology is ready and safe, genetic modification of embryos could be allowed when there is a “serious disease or condition” to be addressed and no “reasonable alternatives” exist.

This scientific criticism of He’s experiment was on target: Although HIV infection is a serious disease, there are proven ways to prevent transmission of the virus from an infected father to his offspring, and later in life to prevent or treat the infection.

That said, scientists criticizing He on the grounds that he did not treat a serious condition with no alternatives imply that other applications of CRISPR to modify eggs, sperm, or embryos could meet this standard. Indeed, many scientists hail reproductive applications of CRISPR (what I call rCRISPR) as potentially lifesaving and curative.


As I argued recently in the journal Bioethics, that claim for rCRISPR is mistaken and misleading. rCRISPR does not save lives or cure diseases that would otherwise exist. It merely aids in creating a person without a particular genetic disease who would otherwise not exist. The value here in creating healthy people — as opposed to healing people who would otherwise be sick — is nominal to none. If you are a genetically healthy person, you have a high chance of creating a healthy person right now. But nobody thinks you have an urgent moral reason to do so.

Let me be clear: I believe there are applications of CRISPR that do correctly purport to cure diseases in people who would otherwise have them. CRISPR-based gene therapies known as somatic applications, which are used in the bodies of people who have genetic diseases, have great curative potential. These aren’t the target of my critique. In fact, it would be much better if we invested the money spent on reproductive CRISPR applications on somatic ones instead.

Here’s why I say that using rCRISPR to modify eggs, sperm, and embryos does not cure disease.

Imagine an individual or couple at high risk for creating a child with a serious genetic disease. They have the following simplified range of options:

  1. Create a genetically related child in the time-honored fashion who will be at high risk for the genetic disease.
  2. Create a genetically related child using CRISPR who will be at very low risk for the genetic disease.
  3. Create no genetically related child.

The existence of option C undermines the claim that rCRISPR applications are lifesaving or curative. If the prospective parent did not have option B available to them, option A would not inevitably happen, meaning they would not inevitably have a sick child. Individuals have a choice in the matter of creating children at high risk of genetic disease: They can choose option C.

Here is a different way of seeing the point that rCRISPR is not morally urgent because it does not involve a child whose existence, or illness, is inevitable. Compare the following scenarios: A doctor creates a cure for a serious and debilitating disease and administers it to a seriously sick child, thus healing her. This doctor saved a life, a morally commendable action. Now imagine that the doctor first injected the disease into the child that he cured. Now his action in its totality could hardly be called curative, for he first created the harm. His seemingly heroic act of healing now has dubious moral value.

This is similar to what occurs with rCRISPR. A clinician first creates an embryo with genetic defects, and then “rescues” it using rCRISPR. Calling this a cure or a therapy is a nonstandard use of those concepts, one that warrants a distinction from standard cures that save lives and prevent otherwise probable harms.

The analogy shows that an otherwise good act or cure can have its moral value undermined if it is part of a greater act that caused the disease in the first place.

Saying that people at risk for passing on serious genetic disease to their offspring can simply not have genetic children at all may seem harsh. But there are several options available to such individuals for becoming parents. They could adopt a child, an often-overlooked opportunity to become a parent that also helps an existing child in need of a family. They could use the egg or sperm of a healthy donor to create a child. Both of these options are expensive, but not more so than rCRISPR.

Prospective parents could also create genetically related children using pre-implantation genetic diagnosis. In this process, an individual’s eggs or sperm are used in conjunction with a partner or donor’s gametes to create several embryos that are then genetically screened for the disease in question. Only healthy embryos are implanted for pregnancy. Pre-implantation genetic diagnosis is a safe technology that is being used today.

Reproductive applications of CRISPR simply cannot meet the criteria laid out by the U.S. national academies. They will not address a serious condition, because rCRISPR is used in the creation of a person who does not have to exist at all. Nonexistence is no condition, and thus not a serious one.

The real value of rCRISPR is not to the individual who is created but to the people who choose to use it to create a child. It helps individuals achieve their reproductive preferences by having genetically related children free of genetic diseases. But this preference, although perhaps deeply held by many, is not a medical need or an urgent one. And pre-implantation genetic diagnosis already enables people to meet this preference.

We should object to the investment of precious medical resources in bringing rCRISPR to market when there are serious and urgent medical needs that could be met elsewhere, including investing in somatic gene therapies that actually treat diseases.

Tina Rulli, Ph.D., is an assistant professor of philosophy at the University of California, Davis, and a member of the UC Davis Ethics Commons.

  • While I agree with some statements in this article I also disagree with many
    such as the point you made that putting a genetic disorder in an embryo then curing it is morally wrong, I agree with that, however how will we solve this problem without researching and experimenting with it first?
    Let me put it this way, if you are making a bomb you have to make it explode to make sure it works.
    The same way to cure genetic issues you have to make sure it works.
    (also I don’t encourage or promote making and testing bombs)

  • I’m at a loss of words. This was one of the most misled and uniformed pieces of writing i’ve ever read. I wouldn’t even know where to begin arguing at the faults in this ideology, as it’s like trying to make a strainer into a bowl, there are just too many holes. In science and medicine there are ethics, not morals. Money is distributed to teams to research physics, which will be used for weapons. The science is good, the outcome is in the eye of the beholder. Money is given to study evolution transitional species, again, interesting science, but it doesn’t “heal people”. Scientific research provides edification to the world and elucidation in the darkness of the universe. Everyone is entitled to their own opinion, but an article written without even a basic understanding of science and medicine which is heavily criticizing the forefront of the fields.. It’s ugly. In short, the general flow of misconceptions and dissemination of misinformation in the article : Existing ways of creating a child from an HIV positive father? it’s simple hm? It’s a standard practice, but i guess we shouldn’t improve? it’s also a proof of concept, as in the embryo it’s much easier to do this (crispr) than in the matured organism. The assumed idea of healthy people have healthy children is completely flawed, and i’m at a loss as a geneticist. The incidences of complicated pathologies which are present in the population is remarkably frequent. Somethings to consider: pregnancies are a dangerous matter, late term abortions are dangerous, having a child with a genetic disease is a burden on the parents, the family, and society as a whole. I feel this was not considered here. Actually. Many things weren’t considered here. I learned a valuable lesson during my training “just because you feel strongly about something, doesn’t mean your right, and your opinion is of no value.” It was a moment that embarrassed me into realizing she was right, and i was wrong, and scientific evidence and facts are all that matter. You can’t discredit some body of work, methodology, or practice, just based on your personal ideological beliefs and unfounded negative feelings, and still stand as a member of the scientific community. There must be evidence. Morality? That’s not for us, and don’t use science to prove your morals as being superior, it doesn’t work that way.

    • Dr. Little

      One thing to add and that should clear things out:

      There are no morals or ethics, there is only science.

      Ethics are infatuations or unexplained fears and stand opposite to morals, which are needs and compassionate help.

      Science must always stand next to clear explanations which are moral and help the ones in need.

      As you can see, ethics and fears need to be treated with science. Moral and compassionate help must always be dominant.

      The actual situation of the scientific community and what needs to be done is clear. As well as the situation in every population of the world.

      And you are right. There are no personal beliefs when applying science. I’s always science with a scientific explanation. Your feelings do not count. Science is neutral and you, as a human being are not. You either use it based on moral principles (which are exact and explainable, therefore scientific and mathematical), or you fear it’s application because you do not understand it. And that is the endpoint. People in in need of medical help do not care about ethics. They need a clear application and the ethicist deleted from society because in their relentless beliefs, they do not use statistics or morals to solve a need and help others, they just write literature books based on what they feel and not on what is real. And they need to either be medically treated or convicted because their actions create money for them as an individual person, and hinder the progress of medical technologies, thus depriving the ones who are sick from the help they need. (They are either infatuated psychopaths without knowledge of that scientific discovery or it’s full range of applications, or run of the mill criminals because they, as researchers or what other side-profession they hold, do not act for the benefit of others or the application of that research, but for personal profit.)

      (And on the other hand, are the scientists, who as well can be found of seeking personal financial gain instead of explaining their research to the population they belong to and apply it in medicine, while intentionally holding the choke hold on the welfare of the patients or individuals who need help. The worsening conjecture is that their research would more than pay them back financially and morally by it’s application in good faith but they are pursuing personal wars with other colleagues, either from a psychological standpoint, or a financial one, and they should be convicted as well, for whatever crime or ill intent they have.)

  • Hi Tina,

    I have a question about the analogy of the clinician “first creat[ing] an embryo with genetic defects [and] then rescu[ing] it using rCRISPR”. If a clinician were to use rCRISPR, do they have to first intentionally create an embryo with genetic defects? I guess I am confused about why they would need to do this.

  • Tina and dear readers, I would like to point out that technology is subjugated to good use and the free xhoice of those who need it. Deciding who uses what technology and for what is a fundamental human right. Depriving one person of access to that technology and further more even more people is not only a violation of fundamental human rights, and because it is done on purpose, it is called attempted murder in the case of those who are ill. Please answer me what are your opinions on depriving people of free choice and a healthy life. Money should be invested directly into science and research from all contributors, either states or private businesses and their direct effects (benefits) made accessible to the public immediately. What you are doing and saying is just opening an empty discussion while people die or are unable to have kids
    and debating their decisions. What I’ve wrote above is the only ethic that exists on this planet and what you are doing is wrong. You should be besides them helping them. One small act is enough to save a life. Implementing rules to prevent misuse is a snap as they can be delineated immediately. I don’t think we are facing the same crisis as the FBI wirh Kevin Mitnick in the 80’s.

    • Hi Andreea, We have a limited amount of medical and research resources to go around. So not everyone will be able to have their medical needs and desires satisfied. This is exactly why I’m arguing that investing in rCRISPR, which has low social value and impact (and doesn’t meet an urgent medical need, but rather satisfies a social preference for genetically related children) should not be our top priority. So I think we actually agree on some foundational issues–that people have a human right at stake to be healthy. In a world where many people do not have that right being met, we cannot spend our research dollars on a low impact technology.

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