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The Edit: CRISPR and the Age of Genetic Engineering
We now have a tool that can rewrite the source code of life. The question of whether we should has barely been asked, let alone answered.
We have spent decades debating what we would do if we could edit the human genome. We spent considerably less time noticing that we already can.
Yesterday we talked about climate technology — fusion reactors, direct air capture, green hydrogen, vertical farms, and the uncomfortable gap between Silicon Valley's enthusiasm and the stubborn physics of the real world. Today we are going somewhere considerably more personal. Not the planet's source code. Yours. We are talking about CRISPR — the gene editing technology that has, in roughly a decade, moved from an obscure bacterial immune system to a tool capable of treating inherited diseases, potentially eliminating genetic conditions entirely, and, in one infamous and catastrophically ill-judged case, producing the world's first gene-edited human babies. Buckle up.
The story of CRISPR is one of the most remarkable in the history of science. It is also one of the most ethically consequential. And it is happening right now, whether the ethics have caught up or not.
01 — What CRISPR Actually Is
CRISPR — Clustered Regularly Interspaced Short Palindromic Repeats — is, at its simplest, a molecular scissors. It was discovered not in a laboratory working on human medicine but in the immune systems of bacteria, which use a version of the mechanism to recognise and destroy viral DNA that has attacked them previously. Scientists Jennifer Doudna and Emmanuelle Charpentier figured out how to repurpose this bacterial system into a programmable gene editing tool. In 2020, they received the Nobel Prize in Chemistry for it. The turnaround from discovery to Nobel is remarkably short by the standards of science. The turnaround from discovery to clinical application was even shorter, which is either a testament to the power of the technology or a warning about the pace at which it outran the frameworks designed to govern it. Possibly both.
The mechanics are elegant. You design a short piece of RNA — a "guide RNA" — that matches the specific DNA sequence you want to target. This guide RNA leads a protein called Cas9 to that exact location in the genome. Cas9 cuts both strands of the DNA at that point. The cell's own repair mechanisms then kick in. If you've also provided a template for how the repair should proceed, the cell incorporates it — effectively replacing the original sequence with a new one. If you haven't, the cell repairs the cut imperfectly, disabling the gene. Cut, replace, or disable: three operations. An extraordinary range of possibilities.
Before CRISPR, gene editing existed but was slow, expensive, imprecise, and inaccessible to most researchers. CRISPR made it fast, cheap, relatively precise, and available to essentially any molecular biology laboratory on earth.
That democratisation is both the technology's greatest strength and one of its most significant risks.
02 — What It Has Already Done
In December 2023, the US Food and Drug Administration approved the first CRISPR-based therapeutic: Casgevy, developed by Vertex Pharmaceuticals and CRISPR Therapeutics, for the treatment of sickle cell disease and transfusion-dependent beta-thalassemia. These are inherited blood disorders caused by mutations in the gene that produces haemoglobin. They are debilitating, painful, and historically managed rather than cured. Casgevy edits patients' own stem cells outside the body, then reinfuses them. Early trial data showed that the vast majority of treated patients were free of severe pain crises for at least a year following treatment. For a disease that has caused suffering across generations, this is not incremental progress. This is transformative.
The pipeline behind this first approval is substantial. CRISPR-based approaches are in various stages of development for cancers, HIV, inherited blindness, Duchenne muscular dystrophy, high cholesterol, and a range of other conditions. The breadth is not hype — it reflects the genuine versatility of the underlying mechanism. If a disease has a genetic component that can be targeted, CRISPR offers at least a theoretical route to addressing it at the source rather than managing its consequences.
In agriculture, CRISPR is already being used to develop disease-resistant crops, drought-tolerant varieties, and livestock with improved welfare characteristics. The regulatory framework for CRISPR-edited crops is, in most jurisdictions, considerably more permissive than for traditional GMO approaches, on the basis that CRISPR edits can produce changes indistinguishable from natural mutation. Whether this distinction is scientifically coherent or a regulatory convenience is a debate that has been running since the technology emerged and shows no sign of resolution.
03 — The He Jiankui Catastrophe
In November 2018, a Chinese researcher named He Jiankui announced at a scientific conference in Hong Kong that he had produced the world's first gene-edited human babies — twin girls, born from embryos that had been edited to disable a gene called CCR5, with the stated intention of making them resistant to HIV infection. The announcement did not produce the response He Jiankui had apparently expected. It produced horror.
The scientific community's reaction was immediate and almost uniformly condemnatory. The editing was medically unjustified — the parents were not HIV positive, and existing prevention methods are highly effective. The CCR5 gene has functions beyond HIV susceptibility, and the long-term consequences of disabling it are unknown. The editing was performed in secret, without proper ethical oversight, on embryos that would become people who had no say in the matter and cannot be un-edited. He Jiankui was subsequently convicted of illegal medical practice by a Chinese court and sentenced to three years in prison.
The twins exist. They are growing up somewhere. They carry edits to their germline — meaning edits that, if they have children, will be passed on. The experiment cannot be undone. The people it was performed on were not consulted and could not be.
This is the thing that distinguishes germline editing — editing embryos, eggs, or sperm — from somatic editing, which edits the cells of a living patient and affects only that individual. Germline edits are heritable. They propagate. A mistake, or an unforeseen consequence, does not end with the patient. It continues.
04 — The Designer Baby Question
The He Jiankui case was condemned partly because it was reckless and partly because it crossed a line that the scientific community had drawn, somewhat carefully, around the therapeutic use of germline editing. The line is between editing to prevent disease and editing to enhance characteristics. Sickle cell disease is not a characteristic. It is a condition that causes severe suffering. Editing an embryo to prevent a child from inheriting it sits, for many, in a categorically different space from editing an embryo to produce a child who is taller, more intelligent, more athletic, or more attractive.
The problem is that the line between treatment and enhancement is not always clear. Is editing for deafness treatment or the elimination of a cultural identity? Is editing for susceptibility to Alzheimer's treatment or enhancement? Is editing for below-average predicted height treatment or cosmetic intervention? These are not hypothetical edge cases. They are the questions that will be asked, in courtrooms and ethics committees and fertility clinics, as the technology matures. The answers will not arrive before the technology does.
The deeper concern is access. If germline enhancement becomes available, who can afford it? The scenario in which wealthy parents can purchase genetic advantages for their children that poor parents cannot is not science fiction. It is the straightforward extrapolation of a technology that is expensive to develop and will be expensive to access, applied in a world where health inequality is already profound. A two-tier humanity — not metaphorically, but genetically — is not an outcome that requires malice. It requires only the normal operation of markets applied to an abnormal technology.
05 — The Governance Gap
The international governance of CRISPR is, charitably, a work in progress. There is no binding global treaty on human germline editing. There are recommendations, moratoriums, national regulations that vary dramatically by jurisdiction, and a general agreement in the scientific community that heritable human genome editing should not be pursued clinically until safety and efficacy can be established and broad societal consensus achieved. The He Jiankui case demonstrated that this consensus, however sincere among the majority of researchers, does not prevent individuals from acting outside it.
The regulatory patchwork has practical consequences. Research that is prohibited in one country can be conducted in another. The fertility tourism industry already exists for procedures not available in patients' home jurisdictions. There is no particular reason to think germline editing would be different, once the technology becomes sufficiently reliable and the demand sufficiently present. The question of who governs a technology that can be performed anywhere, that produces changes that cross borders in the bodies of children, and that has consequences that extend across generations, does not have a clean answer. It barely has the beginning of a framework.
What is being built, slowly, is a combination of national regulatory structures, international scientific norms, and the kind of professional consensus that makes researchers reluctant to associate themselves with work that the community considers premature or irresponsible. This is probably the best available mechanism in the absence of binding international law. It is also the mechanism that He Jiankui operated outside of without particular difficulty, right up until the moment he announced what he had done at a public conference.
Tomorrow we are staying inside the body but moving to a different frontier entirely — the brain. Brain-computer interfaces: the technology that proposes to connect human neural tissue directly to machines, what it can already do for people with paralysis and neurological conditions, what Elon Musk's Neuralink is actually building and why, and the set of questions about identity, privacy, and autonomy that nobody has adequately worked through yet. See you then.
Switched On is a daily technology series covering AI, social media, data privacy, and the digital forces reshaping modern life — with no corporate spin, no false comfort, and absolutely no mercy for buzzwords.
