Wading Through the Hype about CRISPR

George Church, a CRISPR pioneer from Harvard University sees possible paths from these legitimate uses to more dubious ones. “I think enhancement will creep in the door in terms of treating serious diseases,” he says. Someone who is losing their faculties to Alzheimer’s disease might turn to gene-editing to stem their cognitive decline. “Then, someone younger with a super high risk of the disease. Then, a business executive who wants to get ahead of the game. Then that same executive who wants to fix his sperm cells.”

But gene-editing might be totally impractical for fixing common diseases, because they are typically influenced by legions of genes. If you took people with the highest risk of, say, schizophrenia, you’d probably need to CRISPR thousands of genes to bring their odds back down to average levels. That’s a terrible idea, for reasons we’ll get to.

The same is true for attributes like intelligence, height, sporting ability, or personality traits, which involve small contributions from thousands of genes, and a massive dollop of environmental influence on the side. “The dishes do not come à la carte,” writes Nathaniel Comfort, a historian of medicine at Johns Hopkins University in Baltimore. “If you believe that made-to-order babies are possible, you oversimplify how genes work.”

So, no matter how precisely we can edit genes, there are some things we won’t be able to edit our way out of—and certainly not safely. Genes rarely do one thing. Those thousands of edits will ripple through the body in unexpected ways. For example, deleting the CCR5 gene would make people resistant to HIV, but also make them 13 times more likely to die of West Nile virus. Tweaking their FUT2 gene might make them less likely to develop Type 1 diabetes but also make them vulnerable to norovirus.

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