Show of mutilated animals Why gene editing is not ready for testing in humans


Big mistake

The scientific community has largely denounced He Jiankui, the researcher who recently claimed to have used CRISPR to alter the genomes of twin babies in China.

An important criticism is that the effects of CRISPR are not understood enough to ensure the well-being of the twins. On Friday, Wall Street Journal has published a disturbing story about the unintended consequences that the CRISPR gene has had on animals, and paints a picture of a technology that is not even ready for testing in humans.

Side effects may include:

O WSJ article describes a number of examples of geneticists using CRISPR to modify livestock to exhibit favorable traits.

In each example, editing worked, but it also produced unwanted side effects. Rabbits and pigs modified to become leaner also developed increased tongues and extra vertebrae, respectively. Goats modified to produce longer cashmere wool got too large in the womb for natural births, while the cattle that scientists modified to wear lighter coats died like calves.

If we still can not stop our CRISPR issues from producing these unintended consequences on animals, we certainly should not edit the genes of humans.

Cranked Up

But we may not need to edit genes for CRISPR to be useful. On Friday, researchers at the University of California at San Francisco published a study in the journal Science in which they describe CRISPRa, a CRISPR variation that requires no editing. Instead of cutting a target gene, this modified system amplifies gene activity.

The most common genetic mutation in severely obese people is in the SIM1 or MC4R genes, both essential for regulating hunger and satiety. For the study, the researchers genetically engineered mice to mutate into one of these genes. So they used CRISPRa to amplify expression of the non-mutated gene. This allowed the mice to regulate their hunger as effectively as if they had no mutation.

Eventually, CRISPRa could allow us to address obesity and a host of other genetic disorders in humans – all without having to take the risk of editing a single gene.


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