At an international summit held in Washington on Thursday, Dec. 3, it was dubbed “irresponsible” to proceed with human gene editing until issues in safety and efficacy are addressed. But what risks does the gene editing technology actually entail?

Gene editing biotechnology known as CRISPR-Cas9 lets scientists alter genes in animals and plants rapidly and in a relatively affordable way. Obtained from a bacterial protein and developed in the last four years, it banks on how bacteria defend against viruses.

This technology works as a kind of molecular scissors able to selectively trim off undesirable genome parts and replace it with new DNA stretches. Its advocates herald its ability to help speed up the prevention of genetic diseases, while critics worry about the unknown, unintended consequences on future generations.

What makes some experts worry about CRISPR, a much-heralded technique to create “designer babies” and enhance the offspring’s intelligence level or athletic ability?

The answer lies in using any gene therapy itself, said Dr. Mitchell Weiss, hematology department chair at St. Jude Children’s Research Center.

"You mess around with the genome, and are you going to shut off something important or turn on something bad?" Dr. Weiss said.

Previous investigational gene therapy were found to have led to cancer in patients. Law and bioethics professor Pilar Ossorio from University of Wisconsin-Madison said that of the various kinds of risks, the “major” one that gets people concerned are “off-target” consequences.

Once a CRISPR gene editing tool, for instance, is put inside a human body, it can travel everywhere and potentially invade non-targeted cells. It will become important to know how to apply the biotechnology only to the cells and tissues that scientists intend to hit, without affecting and damaging the rest.

Ossorio added, however, that more risk may be acceptable for patients with far more serious conditions, and who may have seen existing therapies fail or have no other option.

Some sectors also raised potential abuse and ethical issues, where Ossorio cited that tradition risk-and-benefit assessment applies and help in calculating the effects of new kinds of tools and therapies such as CRISPR.

For Kyle Orwig from the School of Medicine of the University of Pittsburgh, his ethical concerns are centered on medical need, as well as safety and efficacy.

“If you haven't proven safety and efficacy in animal models, you shouldn't proceed to clinical trials. And if you have, you should,” he argued, adding that trials should not bigger than necessary in order to avoid exposing more people to any likely risks.

Photo: NIH Image Gallery | Flickr

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