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Gene-editing damages DNA more than previously thought: study

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A revolutionary gene editing technique hailed as the future of disease eradication and mooted for a Nobel prize may be less precise and cause more cell damage than previously thought, researchers said Monday.

Lab experiments using mouse and human cells revealed that the CRISPR-Cas9 technique “frequently” caused “extensive” gene mutations, a study team reported.

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“This is the first systematic assessment of unexpected events resulting from CRISPR-Cas9 editing,” said Allan Bradley of the Wellcome Sanger Institute in England, where the team conducts research.

The research showed that “changes in the DNA have been seriously underestimated before now,” said Bradley, who co-authored a study published in the journal Nature Biotechnology.

The mutations have not been shown to be harmful, nor benign.

“It is important that anyone thinking of using this technology for gene therapy proceeds with caution and looks very carefully to check for harmful effects,” Bradley said in a statement issued by the institute.

First unveiled about six years ago, CRISPR-Cas9 allows scientists to insert, remove and correct a faulty sequence on a strand of DNA in a cell with pinpoint precision.

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It has raised hopes that one day disease-causing genes could be removed or altered before a baby is even born.

In recent years, CRISPR-Cas9 has repeatedly been predicted to win the Nobel chemistry prize.

CRISPRs — clustered regularly interspaced short palindromic repeats — are part of the immune defence system in bacteria, used to hone in on the exact spot on the genome where the cut should be made.

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Cas9 is a protein used as “scissors” to snip through the faulty gene, which is then replaced or fixed by the cell’s own DNA repair mechanism.

– ‘Safety implications’ –

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The technique’s safety has not yet been proven, and it is not approved for use in human therapy.

So far, researchers have used it to improve hearing in mice going deaf and to fix a disease-causing mutation in cloned, early-stage human embryos.

But the new finding raises “safety implications,” the team said.

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They found “large genetic rearrangements such as DNA deletions and insertions” in cells, which could lead to important genes being switched on or off and causing dangerous changes.

The research also showed that standard tests do not pick up damage to DNA caused by CRISPR-Cas9.

Experts not involved in the study said it was unclear how such large, unintended changes were not noticed before.

But, “the results give no reason to panic or to lose faith in the methods when they are carried out by those who know what they are doing,” said Robin Lovell-Badge of The Francis Crick Institute, a biomedical research centre in London.

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For Francesca Forzano, a consultant in clinical genetics and genomics with the Guy’s and St Thomas’ NHS Foundation Trust, the work showed that CRISPR-Cas9 “is much less safe than previously thought” and that safety-monitoring techniques were “not entirely adequate”.

More research is needed before any clinical application of the method is considered, said Forzano.


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WATCH: AOC dunks on GOP for ‘beclowning themselves’ during Trump’s impeachment

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Rep. Alexandria Ocasio-Cortez (D-NY) blasted her Republican colleagues on national TV on Friday.

Ocasio-Cortez, also known as AOC, is the youngest woman ever elected to the House of Representatives. She was interviewed on MSNBC's "All In" by anchor Chris Hayes.

"Midway through today's impeachment inquiry, the president was accused of witness tampering," Hayes noted. "One of the sharpest rejoinders came from Congresswoman Alexandria Ocasio-Cortez."

The host read her tweet to the live studio audience.

he*

— Alexandria Ocasio-Cortez (@AOC) November 15, 2019

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‘The worst day of the presidency so far for Donald Trump’: Advisor to four presidents

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President Donald Trump has not had a worse day in office than he suffered on Friday, according to a top former White House advisor.

David Gergen served in the administrations of Richard Nixon, Gerald Ford, Ronald Reagan and Bill Clinton. He was interviewed Friday night by CNN's Anderson Cooper.

"If you are looking to throw somebody under the bus, Gordon Sondland would probably be a prime candidate to be next in line to be thrown under the bus," Cooper said.

"I think the president will wait patiently to see what he says and then decide," Gergen replied.

He then offered his analysis of the situation.

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Chris Hayes breaks down the ‘busy day in the criminal chronicles of one President Donald J. Trump’

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MSNBC anchor Chris Hayes connected the dots between all of the bombshell news that was reported Friday in the impeachment hearings into President Donald Trump.

"Good God, today has been ten days and this week has been ten weeks," Hayes said. "And there are a million things happening at once."

"Just in the past couple of hours, for instance, we just got this incredibly incriminating and damning behind closed doors testimony from a U.S. foreign service officer that was still supposed to be kind of like the B-story today, the sideshow," he explained. "It's a guy who works in the U.S. embassy in Ukraine, a guy named David Holmes. He testified behind closed doors that he could hear president Trump talking on the phone to the U.S. Ambassador to the European Union who was an inaugural donor, and they were in a restaurant in Kiev and the president was shouting so loudly on the phone that [Gordon] Sondland had to hold the phone away from his ear because it was hurting his eardrum, so then everyone could hear."

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