Nov 19 2015

Gene Editing Humans

A Chinese team of researchers recently announced that they attempted to edit the genes in human embryos with the genetic disease beta-thalassemia. They used the CRISPR-Cas9 technology, which they said was not successful enough in this application to be used. Some of the embryos resulted in mosaics, with only some of the cells being fixed, and other resulted in unwanted mutations.

While the attempt to fix the genetic disease in embryos was unsuccessful, the announcement has prompted discussion over the ethics of gene editing in humans.


First for some background, because I have not yet written about the CRISPR technology, this is an exciting gene-editing technology that allows for rapid, accurate, and inexpensive gene editing.

CRISPR stands for Clustered Regularly Interspaced Short Pallindromic Repeats, which refers to a sequence of base pairs found on the DNA of bacteria that have this feature. Some bacteria and archaea use CRISPR for adaptive immunity, in order to incorporate bits of DNA from invading viruses into segments of their own DNA in order to target their immune system at those sequences.

Cas refers to CRISPR associated genes. Cas9 is for an endonuclease that can cleave DNA. It can be combined with specific RNA in a system that can either insert or delete genetic sequences into the target DNA.

What all of this means is that the CRISPR system can be used for highly specific and convenient gene editing, either deleting or inserting sequences into target genes. There is an overwhelming consensus that this technology will usher in an age of cheap and easy genetic manipulation.

One private company, for example, offers CRISPR systems to researchers, boasting:

Introducing the only complete genome editing solution designed to expedite your research. Our easy-to-use optimized and validated solutions span the entire cell engineering workflow, making genome editing accessible to anyone at any level.

Gene Editing Human Embryos

Given the controversy over genetically engineering corn, it is no surprise that the prospect of genetically modifying humans will be highly controversial. Despite the fact that the Chinese researchers concluded that the technology is not quite there yet, their announcement has sparked the predictable conversation.

The Huffpo Interview shows two basic attitudes toward this prospect. Dr. Marcy Darnovsky, executive director of the Center for Genetics and Society, is concerned about the implications of the technology. She raises several points, all of which we have heard before with other technologies, including IVF itself. There are safety concerns. The technology can go beyond treating disease to creating new humans and “designer babies.”  She also warns that this technology could lead to those with money creating a superior race, creating a world we would not want to live in. She equates the technology to eugenics.

Antonio Regalado from MIT Technology Review argues that the same objections were raised for IVF, and that the eugenic analogy is not apt since this technology will be voluntary and won’t harm anyone.

I tend to agree with Regalado. Raising safety concerns is a false issue. There are always safety concerns with a new technology, but they can be dealt with. They aren’t a reason to stop the technology. We can evaluate the precision and consequences of using CRISPR on human embryos, and only approve applications when the techniques are sufficiently safe. The same was true of IVF and pretty much any new medical technology.

Before we get to the issue of using CRISPR (or any genetic modification technology) to create enhanced embryos, let’s not forget that the application currently being studied is to correct a genetic illness. Regardless of ethical considerations about the former, we should not let that interfere with a technology that can cure genetic diseases at the embryo stage.

There are actually two approaches here. You can select embryos that lack a harmful mutation, without doing any editing. This is not possible, however, if every embryo is a carrier. Then gene editing is required.

I see no ethical reason to hamper any technology that can treat genetic diseases, which can be devastating and costly, resulting in a lifetime of medical bills. We cannot afford to eschew a potentially cost effective medical intervention given rising health care costs.

I don’t buy the slippery slope argument that such technology will necessarily lead to designer babies. We can use regulations to approve some applications and not others.

The thorny ethical issues, in my opinion, only revolved around creating genetically enhanced people. The argument that such technology would be unethical, or at least a bad idea for society, was articulated by Darnovsky – this can create a truly stratified society in which one race of humans, the offspring of those with money, is perceived to be superior to another.

The primary argument against this objection is that you can say the same thing about iPhones. Almost every technology is more accessible to the wealthy than the poor, and widens the gap between the haves and have nots. We are now dealing with a “digital divide,” where access to computer technology and the internet is yet another social advantage of those with resources over the poor.

I acknowledge that one meaningful difference here is that we are talking about changes to the people themselves, not just the technology to which they have access.

One might argue that the solution to such technology gaps is not to ban the technology so no one can take advantage of it, but to address the underlying social issues themselves. There are also social safety nets in place to provide at least some resources to the poor. Sure, the wealthy can afford organ transplants without having to worry, but poor people still get transplants through Medicaid.

These social systems are not perfect, and they probably never will be. In any society where people are allowed to benefit from their talent, skill, hard work, and even luck, there will be those who have more than others. Historically, this fact does tend to lead to increasing social disparity, but there are many mechanisms to mitigate stratification, allow for social mobility, and to distribute resources equitably.

Exactly how and how much to do this is a huge ideological debate, and pretty much drives the division between liberals and conservatives. I get the feeling that the same liberal/libertarian ideological divide is coloring the debate over gene editing and other similar technologies.

My position is essentially not to bring that ideological fight to medical technology that can be used not only to cure disease but to make humans smarter and healthier. Deal with the underlying social issues. We should no more ban gene editing than we should shut down the internet in order to eliminate the digital divide.

To be clear, we need to regulate genetic manipulation of humans, just like any powerful medical technology. Those regulations should be appropriate to the technology, to ensure safety, informed consent, and appropriate ethical use. We have similar regulations and systems in place for organ donation, for example. It can work.

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