Do we dare edit the human genome?

Open questions in the age of CRISPR

Photo by Kate_Koreneva
So how does CRISPR-Cas9 work? Doudna explains in her own words. Cued up at the scientific meat of the talk.

How does CRISPR-Cas9 work?

The discovery of CRISPR is fascinating but I will not get into it here because it complicates things and is not important for the biotechnology application of CRISPR-Cas9. If interested, a good starting point is to watch the above talk by Doudna.

Using just three molecular ingredients — Cas9, a guide-RNA designed to target your gene of interest, and donor DNA designed to produce a functional, healthy protein — CRISPR-Cas9 can be used to correct disease-related mutations.

This illustration shows guide-RNA (yellow) binding to its complementary sequence in a cell’s DNA (blue), with Cas9 protein (magenta) poised to cut both strands of the DNA. By Meletios Verras.

Why wouldn’t we use CRISPR-Cas9 to cure disease?

The idea of gene therapy, where you introduce a healthy version of a gene into a diseased individual, is not new, but CRISPR-Cas9 is the first biotechnology that is easy, adaptable, and cheap enough to make it feasible. Already being used in research labs across the globe to study both fundamental and disease related biology in many species, CRISPR-Cas9 is making its way into our crops, into the clinic, and into human embryos.

Should we allow heritable gene editing in humans?

A major challenge of using the CRISPR-Cas9 system to cure disease in children and adults is getting those three essential ingredients into all of the diseased cells. Initial clinical trials will likely focus on CRISPR-Cas9 therapies to treat diseases of the blood or other cell types and tissues that are easy to access.

Using established IVF techniques, CRISPR-Cas9 plus donor DNA could be injected into human gametes, such as egg cells, to edit genes in a heritable way. Illustration by Razvan25.

Problem: We don’t want another Hitler.

Potential Solution: Gene editing must be the choice of the individual. Governments and insurance companies must not regulate or coerce us into changing our genes in the way they have decided is best.

Problem: If we edit the genes of our children, we are taking away their right to choose.

Potential Solution: Gene editing must not be heritable.

Problem: Without equal access to gene editing technology, only some of us will be able to change our genes, further dividing humanity along both economic and genetic lines.

Potential Solution: If the edits are not allowed to be heritable, the divide will be restricted to one generation. Doudna believes that with time, this technology will become accessible to all, similar to genome sequencing. Universal health care and covering the costs of disease-related genetic corrections would be one way to smooth things out in the interim, but I can’t currently imagine that happening in the US.

Problem: It is arrogant to think we understand biology well enough to intelligently design ourselves. There will certainly be unintended consequences.

Potential Solution: Further study is needed before this technology is used in human beings. That said, we will never know enough and will ultimately be taking a gamble. If we initially limit ourselves to using this technology as a therapy for disease in a way that is not heritable, we will limit our risks.

Only fools rush in

Based on my potential solutions above, it appears my personal instinct is that heritable germline editing should remain off limits for a lot longer. I would be much more comfortable with gene editing of targeted cell types in diseased individuals. Better gene therapy delivery methods are needed whether or not CRISPR turns out to be the fix all, so I think that is the most important area to focus on for good clinical outcomes.

Thanks for reading

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Exploring human experience through science and stories. My first book, “Kegels Are Not Going to Fix This,” available now.