/CRISPR Gene Editing in Human Embryos Wreaks Chromosome Mayhem

CRISPR Gene Editing in Human Embryos Wreaks Chromosome Mayhem

Summary: Three studies showing large DNA deletions and reshuffling heighten safety concerns about heritable genome editing

Original author and publication date: Heidi Ledford – June 25, 2020

Futurizonte Editor’s Note: According to the article, gene editing creates “unwanted effects”. Really? What a surprise! There was no way to anticipate that manipulating human DNA would have “unwanted effects”.

Image for illustration purposes only. Photo by National Cancer Institute on Unsplash

From the article:

A suite of experiments that use the gene-editing tool CRISPR–Cas9 to modify human embryos have revealed how the process can make large, unwanted changes to the genome at or near the target site.

The studies were published this month on the preprint server bioRxiv, and have not yet been peer-reviewed. But taken together, they give scientists a good look at what some say is an underappreciated risk of CRISPR–Cas9 editing. Previous experiments have revealed that the tool can make ‘off target’ gene mutations far from the target site, but the nearby changes identified in the latest studies can be missed by standard assessment methods.

“The on-target effects are more important and would be much more difficult to eliminate,” says Gaétan Burgio, a geneticist at the Australian National University in Canberra.

These safety concerns are likely to inform the ongoing debate over whether scientists should edit human embryos to prevent genetic diseases—a process that is controversial because it creates a permanent change to the genome that can be passed down for generations. “If human embryo editing for reproductive purposes or germline editing were space flight, the new data are the equivalent of having the rocket explode at the launch pad before take-off,” says Fyodor Urnov, who studies genome editing at the University of California, Berkeley, but was not involved in any of the latest research.

UNWANTED EFFECTS
Researchers conducted the first experiments using CRISPR to edit human embryos in 2015. Since then, a handful of teams around the world have begun to explore the process, which aims to make precise edits to genes. But such studies are still rare and are generally strictly regulated.

The latest research underscores how little is known about how human embryos repair DNA cut by the genome-editing tools—a key step in CRISPR–Cas9 editing, says reproductive biologist Mary Herbert at Newcastle University, UK.

“We need a basic road map of what’s going on in there before we start hitting it with DNA-cutting enzymes,” she says.

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