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Genetic Linkage

Viewpoint: Putting CRISPR babies in context—learning from the past instead of panicking in the present

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The birth announcement for the first human babies conceived using gene editing, to prevent an infection, came via YouTube on November 25.

In the words of researcher He Jiankui, of Southern University of Science and Technology in Shenzhen:

Two Chinese girls, who we’ll call Lulu and Nana to protect their privacy, were born healthy a few weeks ago. Their mother Grace started her pregnancy by regular IVF with one difference: right after sending her husband’s sperm into her eggs, an embryologist also sent in CRISPR/Cas9 protein and instructions to perform a gene surgery intended to protect the girls from future HIV infection. The surgery reproduces a natural genetic variation shared by more than 100 million people of primarily European origin that confers strong resistance to initial HIV-1 infection and disease progression.

Dr. He went on to briefly explain the safety measures taken: genome sequencing before the early embyros implanted in the uterus, during the pregnancy, and after birth. “These data indicate the girls’ genomes were changed as intended by the gene surgery, but no off-target editing or large deletions occurred,” he concluded, saying his team would publish the findings soon.

To continue reading go to Genetic Literacy Project, where this article first appeared. Read More 

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Mosquito massacre: Can we safely tackle malaria with a CRISPR gene drive?

CRISPR-Cas9 gene editing quickly decimated two caged populations of malaria-bearing mosquitoes (Anopheles gambiae) in a recent study, introducing a new way to solve an age-old problem. But the paper describing the feat in Nature Biotechnology had a broader meaning regarding the value of basic research. It also prompts us to consider the risks and rewards of releasing such a powerful gene drive into the wild.

Instead of altering a gene affecting production of a reproductive hormone, the editing has a more fundamental target: a gene that determines sex. The work was done by Andrea Crisanti and colleagues at Imperial College London. Their clever use of the ancient insect mutation doublesex rang a bell for me — I’d used a fruit fly version in grad school.

To continue reading go to Genetic Literacy Project, where this post first appeared. Read More 
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Is CRISPR Gene Editing Doomed, Even As Gene Therapy Enters the Clinic?

Anyone watching the recent 60 Minutes segment on CRISPR would conclude that the gene editing technology is on the brink of pouring forth a cascade of cures. But a recent study reveals a mess of missing and moved chromosome parts in the wake of deploying the famed “molecular scissors.”

Invented in 2012, CRISPR brilliantly borrows a bacterial defense against infection. The “clustered regularly interspaced short palindromic repeats” are simple DNA sequences that serve as landing strips in a genome where engineered “guide RNAs” deliver an enzyme to a desired gene, amending or obliterating it. When the enzyme snips across the double helix, natural DNA repair ensues. Cas9 is an oft-used enzyme.

Precision

Unlike conventional gene therapy that adds a gene, sometimes hovering in a DNA loop outside a chromosome, CRISPR swaps in or removes a gene at a precise spot. But it took 27 years for the FDA to approve the first gene therapy, Luxturna, to treat a specific form of hereditary blindness, last December. So CRISPRed drugs won’t be hitting CVS or Walgreen’s shelves anytime soon.

The new report, in Nature Biotechnology, from researchers at the Wellcome Sanger Institute, isn’t the first to find a CRISPR glitch, and it certainly won’t be the last.

To continue reading go to DNA Science Blog, where this post first appeared.  Read More 
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Rampage: Jurassic Park Lite with a Helping of CRISPR Critters

Is a film based on a video game with fleeting mentions of a biotech buzzword compelling sci-fi? No. But I liked Rampage anyway.

The use of CRISPR to edit genes is perhaps the only novel plot point in this latest monster movie. An evil head of a biotech company subverts a scientist’s work to fashion a bioweapon that revs up the growth hormone gene, and more, in three unfortunate animals. Cue Godzilla, King Kong, and the beast in Lake PlacidRead More 
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Can CRISPR Conquer Huntington’s?

In HD extended huntingtin protein builds up in medium spiny neurons in the striatum.
I set a high bar for writing about mouse studies. I don’t include them in my textbooks or news articles, and only rarely blog about them. But when experiments in mice shine a glimmer of hope on a horrific illness with a long history of failed treatments, I pay attention. That happened last week for a report on editing out of mice the human version of the mutant Htt gene that causes Huntington disease (HD), published in the Journal of Clinical InvestigationRead More 
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CRISPR Clarifies Split-Hand/Foot

A mother and two daughters who have "lobster claw deformity."
While James R. Clapper, Director of National Intelligence, calls genome editing a "national security threat", bioethicists warn of CRISPR-created superbabies, and prominent researchers argue whether patents trump papers, I prefer to quietly look at applications of the technology that aren’t dramatic enough to enter the endless news cycle, but elegantly reveal the power of the technology. Read More 
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Will Layla Save Gene Editing?

(Great Ormond Street Hospital)
I had planned to blast last Thursday’s news of the use of gene-editing to save a British baby from aggressive leukemia. “Two months later, Layla was cancer-free,” proclaimed one of many enthusiastic reports.

I’m always skeptical when I hear the words “cancer” and “cure” in the same sentence, let alone uttered so soon after treatment and without an accompanying technical paper so I can see the data. But when I considered the timing of unfolding events, I realized that the seemingly premature reporting of Layla’s rapidly restored health just might add an important point to the heated discussion over gene and genome editing. That is, can we keep the promising clinical applications on somatic cells, while forbidding the Frankenstein scenarios of germline manipulation? Read More 
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CRISPR Meets iPS: Technologies Converge to Tackle Sickle Cell Disease

Researchers from Johns Hopkins University have teamed two powerful technologies to correct sickle cell disease in a lab dish. Linzhao Cheng and colleagues have deployed CRISPR/Cas-9 on iPS cells to replace the mutant beta globin gene, published in Stem Cells.

ACRONYMS AND ABBREVIATIONS

CRISPR conjures up images of fried chicken, but it stands for “clustered regularly interspaced short palindromic repeats” – short repeated DNA sequences interspersed with areas called spacers, like stutters. The pattern of repeats and spaces attracts an enzyme, Cas9, which is like a molecular scissors that cuts wherever short RNA molecules called “guide RNAs” take it. Here’s a fuller descriptionRead More 
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