Since being released on the world in 2012, the biotechnological tool CRISPR has been making headlines. Biologists used to rely on the relatively blunt tools of genetic modification, but this new tool is so precise and versatile that they now speak of gene editing instead. For people in a hurry, Nessa Carey here provides a primer on the powers and pitfalls of gene editing. Hacking the Code of Life is accessible to readers without much background in genetics, focusing more on the applications and the questions it raises than the nitty-gritty details of the tool itself.
I previously reviewed A Crack in Creation: The New Power to Control Evolution, written by one CRISPR’s inventors, Jennifer Doudna. This still stands as a definitive introduction that should give interested biologists, in particular, a run for their money where all the biological details are concerned. Carey has previously written very accessible books on epigenetics (The Epigenetics Revolution: How Modern Biology is Rewriting Our Understanding of Genetics, Disease and Inheritance) and junk DNA (Junk DNA: A Journey Through the Dark Matter of the Genome) that were quite chunky books. The first thing, therefore, that struck me about Hacking the Code of Life was that it is a small, 181-page paperback. No doubt to maximise the book’s reach, she has kept matters light – consider that the term CRISPR is relegated to a footnote, with the more general term gene editing used throughout.
Two chapters introduce the basics of DNA and how we modified it pre-gene editing, followed by the essentials of CRISPR’s discovery and functioning. Carey draws parallels to how word processors changed the process of writing to explain what makes gene editing such a novel and special technique: we simply did not have a tool with this level of precision, versatility, and ease-of-use before.
But it is the applications and the questions these raise that are the focus of this book. Carey considers the editing of plant, animal, and human genetic material, outlining the many advantages. The speed and ease with which we can improve crop yields, disease resistance, and robustness are unprecedented. Though still on the drawing board, editing animal genes could eliminate diseases in livestock and make meat production more efficient. It also opens up new avenues for the production of pharmaceuticals, especially drugs that are so far simply too complex to synthesize in a test tube, or too expensive for healthcare providers to develop. In humans we could even treat genetic disorders, simply removing mutations in our DNA that cause them.
“we simply did not have a tool with this level of precision, versatility, and ease-of-use before”
Throughout, Carey is very clearly on the side of Team Science. Much like Mark Lynas (see my review of Seeds of Science: Why We Got It So Wrong on GMOs), she is frustrated by the public opposition to genetic modification, often fueled by environmental NGOs, and the sometimes irrational regulations it has resulted in. European rules allow plant breeders to induce random, off-target genetic changes in their plants using “traditional” horticultural techniques such as irradiation or exposure to chemicals, but not precise, on-target genetic changes with gene editing. Go figure.
But being on Team Science also means dispelling hyperbole. The idea of editing genetic material in humans usually meets with two types of response. One is the fear of eugenic-style practices aimed at creating “designer babies” or superhumans. But, as Carey explains, in reality many of the traits we would like to target are polygenic – influenced by many (many!) genes of small effect (see also my review of Blueprint: How DNA Makes Us Who We Are). The other is the hope that we will be able to cure numerous diseases. To have her analytically list all the conditions and diseases that are not feasible targets is a necessary but almost depressing exercise. Of course, things move fast, especially in this field, but a healthy dose of realism is in order.
Lastly, Team Science members ought to be cautious. Jennifer Doudna was very worried when she released this technique on the world and has argued for a moratorium on human germline gene editing (i.e. editing genes in cells that will be passed on to the next generation, which includes sperm and egg cells). Her hopes for a universal cautious and thoughtful approach were shattered by the announcement of Chinese scientist He Jiankui that he had created gene-edited babies (see Ed Yong’s piece in The Atlantic). Carey discusses and criticises this debacle, and, more generally, the PR damage inflicted by poorly executed experiments rushed into print, leading to widespread but unwarranted public distrust. But she also explains genuinely powerful applications of gene editing, such as gene drives and beforementioned germline gene editing, that need to be approached with a great deal of thought.
“To have [Carey] analytically list all the conditions and diseases that are not feasible targets [of gene-editing] is a necessary but almost depressing exercise”
Human gene editing raises ethical dilemmas and Carey asks many interesting rhetorical questions that she leaves for the reader to ponder. The forthcoming Altered Inheritance: CRISPR and the Ethics of Human Genome Editing will go into such questions far more in-depth, but she provides a useful taster here. Gene editing of germline cells could create permanent, heritable changes. But is it ethical to be meddling with the genetic material of future generations? If we can literally “fix” diseases (not an outlandish proposal for some conditions), is it ethical to withhold treatment? Does the possibility of gene editing change how we consider disabled people? And what if disabled people want to have children that could inherit a condition that could be addressed by gene editing (the example of congenital deafness is given), who decides what is best for the child?
Despite the book’s brevity, Carey even finds space to discuss the main players in the development of gene editing and how they ended up at odds with each other, with battles over patents being fought in court. Jim Kozubek detailed this in Modern Prometheus: Editing the Human Genome with CRISPR-Cas9, but it is her accessible writing that make her summary preferable.
Hacking the Code of Life is not intended to be an exhaustive book on gene editing and CRISPR – several other books already fill that niche. But given how topical and wide-reaching gene editing is, this primer for a general audience is incredibly welcome.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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