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U.S. Human Embryo Editing Study Published

posted by martyb on Thursday August 03 2017, @10:47PM   
from the the-best-made-plans-of-mice-and-men... dept.

takyon writes:

The human embryo editing study first reported by MIT Technology Review last week has been published in Nature. Scientists led by the Oregon Health & Science University's Shoukhrat Mitalipov edited human embryos to remove the MYBPC3 mutation associated with hypertrophic cardiomyopathy:

The experiment corrected the defect in nearly two-thirds of several dozen embryos, without causing potentially dangerous mutations elsewhere in the DNA.

None of the embryos were used to try to create a baby. But if future experiments confirm the techniques are safe and effective, the scientists say the same approach could be used to prevent a long list of inheritable diseases. "Potentially, we're talking about thousands of genes and thousands of patients," says Paula Amato, an associate professor of obstetrics and gynecology at Oregon Health & Science University in Portland. She was a member of the scientific team from the U.S., China and South Korea.

[...] Amato and others stress that their work is aimed at preventing terrible diseases, not creating genetically enhanced people. And they note that much more research is needed to confirm the technique is safe and effective before anyone tries to make a baby this way. But scientists hoping to continue the work in the U.S. face many regulatory obstacles. The National Institutes of Health will not fund any research involving human embryos (the new work was funded by Oregon Health & Science University). And the Food and Drug Administration is prohibited by Congress from considering any experiments that involve genetically modified human embryos.

Nevertheless, the researchers say they're hopeful about continuing the work, perhaps in Britain. The United Kingdom has permitted genetic experiments involving human embryos forbidden in the United States. "If other countries would be interested, we would be happy to work with their regulatory bodies," says Shoukhrat Mitalipov, director of the Oregon Health & Science University's Center for Embryonic Cell and Gene Therapy.

Also at NYT, MIT, BBC, Science Magazine, and Scientific American.

Correction of a pathogenic gene mutation in human embryos (open, DOI: 10.1038/nature23305) (DX)

Previously: First Known Attempt at Genetically Modifying Human Embryos in the U.S. is an Apparent Success

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Original Submission

• It just seems wrong (Score: 1, Insightful) by Anonymous Coward on Thursday August 03 2017, @11:37PM

  by Anonymous Coward on Thursday August 03 2017, @11:37PM (#548521)

  Using sperm from a man with hypertrophic cardiomyopathy and eggs from 12 healthy women, the researchers created fertilized eggs. Injecting CRISPR-Cas9, which works as a genetic scissors, they snipped out the mutated DNA sequence on the male MYBPC3 gene.

  They injected a synthetic healthy DNA sequence into the fertilized egg, expecting that the male genome would copy that sequence into the cut portion. That is how this gene-editing process works in other cells in the body, and in mouse embryos, Dr. Mitalipov said.

  Instead, the male gene copied the healthy sequence from the female gene. The authors don’t know why it happened.

  [...]

  The researchers also discovered something unexpected: a previously unknown way that embryos repair themselves.

  In other cells in the body, the editing process is carried out by genes that copy a DNA template introduced by scientists. In these embryos, the sperm cell’s mutant gene ignored that template and instead copied the healthy DNA sequence from the egg cell.

  “We were so surprised that we just couldn’t get this template that we made to be used,” said Shoukhrat Mitalipov, director of the Center for Embryonic Cell and Gene Therapy at Oregon Health and Science University and senior author of the study. “It was very new and unusual.”

  https://www.nytimes.com/2017/08/02/science/gene-editing-human-embryos.html [nytimes.com]

  Even more remarkably, the majority of targeted blastomeres (63.6%, 35/55) resolved the DSBs by HDR using the wild-type allele, also markedly different from what was seen in iPSCs (Fig. 2d and Extended Data Fig. 2a). We did not find any evidence of HDR using exogenous ssODN, suggesting that HDR is guided exclusively by the wild-type maternal allele.

  https://www.nature.com/nature/journal/vaop/ncurrent/full/nature23305.html [nature.com]

  So they had 70 zygotes (extended data table 2) that were about 50/50 wt (wildtype) and mutant (the sperm were from a heterozygous guy). They ended up with 36/54 wt embryos (fig 2a), when they had ~35 wt zygotes to start with. Doesn't this sound like they just killed/damaged 16 of the mutant zygotes since they targeted an enzyme that damages DNA to cells with the mutant sequence? Wouldn't this also explain their strange, surprising result that the "edited" cells contained WT sequence rather than the one they injected into the cells?

  This all seems very straightforward to me with no mysteries, surprises, remarkable findings, or anything unusual other than the fact they insist that some kind of "editing" is going on...

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