The media well and truly pricked up its collective ears when US geneticist Shoukhrat Mitalipov last month showed that he could use the CRISPR gene-editing system in a very early human embryo to correct a mutation that can cause heart defects.
Such excitement is understandable. Even if his work wasn鈥檛 the first of its type, it was arguably the most sophisticated and had the most promising results, a proof in principle that opens the door to possibly modifying other genes. How about targeting a mutated APP gene, linked to risk of early-onset Alzheimer鈥檚? Or mutated BRCA genes, linked to risk of breast or ovarian cancer, or a that can boost athletic potential?
Enthusiasm must be tempered though. Mutations in BRCA genes, for example, are nested in complex relationships with other genes. It would be impossible to know if modifying a single BRCA gene would reduce cancer risk until we tried.
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We could also add mutations with known benefits. One is possible in the gene PCSK9 that and the risk of ischaemic stroke. But having LDL that is too low raises the risk of another problem: haemorrhagic stroke. Such gains rarely come for free.
But where might the first gene-edited baby be born? There are reasons to doubt it will be in the US. In February, the National Academies of Sciences published a report, , that gives support for gene editing for human reproductive purposes, but only in cases where no safer, existing options are available.
Crucially, the existing method of can usually generate one without a heritable mutation because there is a 50 per cent chance of not passing on a disease causing gene in almost all instances. So those cases envisioned by the academies 鈥� where CRISPR is the only option to eliminate a chance of inheriting a genetic illness 鈥� are likely to be true rarities.
Widespread disease risk
What鈥檚 more, US medical insurance coverage is unlikely to deem prophylactic gene-modification techniques 鈥渕edically necessary鈥�. Doing so would challenge the entire concept of necessity, since unknowingly carry some sort of recessive genetic variant that raises a disease risk for offspring.
In addition, the US Food and Drug Administration regards CRISPR as a drug, rather than a device. So although there is no explicit ban on using it to engineer a baby at an IVF clinic, it does mean the agency can enforce regulations relating to an 鈥渋nvestigational new drug鈥�. As a result, CRISPR has to go through a regulatory pathway for each DNA target it is used to modify, and approval could take a decade or more. The FDA might raid any clinic trying to use unlicensed CRISPR to engineer a baby.
The most immediate concern then is that only wealthy Americans may be able to create gene-edited babies by going abroad to countries willing to allow it. I see this happening within five years. And here we shift to wider fears. called biotechnological transhumanism 鈥渢he world鈥檚 most dangerous idea鈥� since it could dramatically worsen inequality by creating a biologically healthier class.
Since every generation mixes DNA in the exciting events of reproductive roulette, such class distinctions are unlikely to be permanent. We should also take heart that over millions of years of evolution, the human genome is close to optimal. However, we can and should be prepared for new forms of techno-scientific racism, and inequalities in insurance and health if the gene-modified emerge among us.
The human germline isn鈥檛 a sacrosanct document. It is a living document that changes in our lifetimes. Inevitably, someone will use CRISPR to alter it further. A bit like the , once a CRISPR baby is born, the most important questions may then become how we treat them, and what their arrival does to our concept of self and soul.
