CRISPR used to peer into human embryos’ first days

Sep 21, 2017

By Heidi Ledford

Gene-edited human embryos have offered a glimpse into the earliest stages of development, while hinting at the role of a pivotal protein that guides embryo growth.

The first-of-its-kind study stands in contrast to previous research that attempted to fix disease-causing mutations in human embryos, in the hope of eventually preventing genetic disorders. Whereas those studies raised concerns over potential ‘designer babies’, the latest paper describes basic research that aims to understand human embryo development and causes of miscarriage.

Published online today in Nature1, the study relied on CRISPR–Cas9, a gene-editing system that can make precise changes to DNA in the genome. In this case, researchers harnessed CRISPR–Cas9 to disrupt the production of a protein called OCT4 that is important for embryo development.

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2 comments on “CRISPR used to peer into human embryos’ first days

  • I see that human gene editing is also proceeding in China!

    Precise “chemical surgery” has been performed on human embryos to remove disease in a world first, Chinese researchers have told the BBC.

    The team at Sun Yat-sen University used a technique called base editing to correct a single error out of the three billion “letters” of our genetic code.

    They altered lab-made embryos to remove the disease beta-thalassemia. The embryos were not implanted.

    The team says the approach may one day treat a range of inherited diseases.

    Base editing alters the fundamental building blocks of DNA: the four bases adenine, cytosine, guanine and thymine.

    The potentially life-threatening blood disorder beta-thalassemia is caused by a change to a single base in the genetic code – known as a point mutation.

    The team in China edited it back.

    They scanned DNA for the error then converted a G to an A, correcting the fault.

    Junjiu Huang, one of the researchers, told the BBC News website: “We are the first to demonstrate the feasibility of curing genetic disease in human embryos by base editor system.”

    He said their study opens new avenues for treating patients and preventing babies being born with beta-thalassemia, “and even other inherited diseases”.

    The experiments were performed in tissues taken from a patient with the blood disorder and in human embryos made through cloning.

    Base editing is an advance on a form of gene-editing known as Crispr, that is already revolutionising science.

    Crispr breaks DNA. When the body tries to repair the break, it deactivates a set of instructions called a gene. It is also an opportunity to insert new genetic information.

    Base editing works on the DNA bases themselves to convert one into another.

    Prof David Liu, who pioneered base editing at Harvard University, describes the approach as “chemical surgery”.

    He says the technique is more efficient and has fewer unwanted side-effects than Crispr.

    He told the BBC: “About two-thirds of known human genetic variants associated with disease are point mutations.

    “So base editing has the potential to directly correct, or reproduce for research purposes, many pathogenic [mutations].”

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  • So while Trump is cutting science budgets, appointing science deniers, science illiterates, and ignorant bigots, to senior government positions, thus making American government a laughing stock, the scientists of the USA have been making world leading breakthroughs, with the potential to be world leaders!

    Three scientists who unravelled how our bodies tell time have won the 2017 Nobel Prize for physiology or medicine.

    The body clock – or circadian rhythm – is the reason we want to sleep at night, but it also drives huge changes in behaviour and body function.

    The US scientists Jeffrey Hall, Michael Rosbash and Michael Young will share the prize.

    The Nobel prize committee said their findings had “vast implications for our health and wellbeing”.

    A clock ticks in nearly every cell of the human body, as well as in plants, animals and fungi.

    Our mood, hormone levels, body temperature and metabolism all fluctuate in a daily rhythm.

    The body clock so precisely controls our body to match day and night that disrupting it can have profound implications.

    The ghastly experience of jet lag is caused by the body being out of sync with the world around it.

    In the short term, body clock disruption affects memory formation, but in the long term it increases the risk of diseases, including type 2 diabetes, cancer and heart disease.

    “If we screw that system up we have a big impact on our metabolism,” said Prof Russell Foster, a body clock scientist at the University of Oxford.

    He told the BBC he was “very delighted” that the US trio had won, saying they deserved the prize for being the first to explain how the system worked.

    Even our risk of a heart attack soars every morning as our body gets the engine running to start a new day.

    The trio’s breakthroughs were on fruit flies, but their findings explain how “molecular feedback loops” keep time in all animals.

    Jeffrey Hall and Michael Rosbash isolated a section of DNA called the period gene, which had been implicated in the circadian rhythm.

    The period gene contained instructions for making a protein called PER. As levels of PER increased, it turned off its own genetic instructions.

    As a result, levels of the PER protein oscillate over a 24-hour cycle – rising during the night and falling during the day.

    Michael Young discovered a gene called timeless and another one called doubletime. They both affect the stability of PER.

    If PER is more stable then the clock ticks more slowly, if it is less stable then it runs too fast. The stability of PER is one reason some of us are morning larks and others are night owls.

    Together, they had uncovered the workings of the molecular clock inside the fly’s cells.

    Dr Michael Hastings, who researches circadian timing at the MRC Laboratory of Molecular Biology, told the BBC: “Before this work in fruit flies we really didn’t have any ideas of the genetic mechanism – body clocks were viewed as a black box on a par with astrology.”

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