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Genetically Modifying Human Embryos: What You Need To Know

The licence to genetically modify human embryos is not a green light to create "designer babies".

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Scientists in the UK have been given a licence to edit the genes of human embryos.


A team at the Francis Crick Institute, led by the embryologist Dr Kathy Niakan, applied for the licence in September. Now, the Human Fertilisation and Embryology Authority (HFEA) has granted the team's request.

However, this doesn't mean that the research can now go ahead.

There is another hurdle – ethical approval of the study itself. But the granting of a licence is a key step.

The team will use a new genetic modification technique called CRISPR, which allows very specific edits to be made to genomes.


They hope that by removing genes from, or adding them to, the early embryo, they will be able to learn more about how healthy embryos develop.

"It's a fundamental study on the function of some of the genes on early human development," Professor Darren Griffin, a geneticist at the University of Kent, told BuzzFeed News. They could learn, for instance, whether certain genes are involved in the early termination of pregnancies.


The research could help develop treatments for infertility.

A better understanding of what makes embryos succeed or fail could mean new hope for would-be parents who are struggling to conceive, said Griffin.

It could also help research into stem cells, which could lead to other medical breakthroughs.

Britain is ahead of the world on research like this.

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The UK is a world leader in genetic research, said Griffin, as shown both by this decision and the recent law change allowing mitochondrial DNA donation (the "three-parent baby" technique).

This is in large part down to "great British common sense", he said. "There's a lot of things we do wrong, but on balance we don't go in for scare stories quite so much; we take things on their merits."

Having a dedicated regulator, the HFEA, which looks solely at the issues around embryology and fertility – instead of leaving these decisions to a less well-informed general medical regulator, or to legislation – helps too. "It's easy to complain about a regulator, but when you look at the big picture you see that the UK is leading the way," said Griffin.

CRISPR is a genetic technique used by bacteria to defend themselves against viruses.

When a virus invades a cell, the bacterium can cut out a section of the virus's DNA and store it in its own genome, so that it will recognise that virus in future. By using the same technique, scientists can now cut out specific genes and insert them, very accurately, into the genome. "In simple terms it's like a pair of scissors that cuts out the gene and replaces it with another one," said Griffin.

Previous techniques were much less accurate, Griffin said: "You don't really know if it's going in the right place, so you don't know if your edit is precise enough." CRISPR has made gene editing much faster, more accurate, and cheaper.

This licence absolutely does not mean that scientists can create genetically modified babies.

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By law, all human embryos used in research must be destroyed by the time they are 14 days old, and Niakan's research is no different.

However, it is technically possible, and soon we will probably having a discussion over whether or not it's the right thing to do. "There's certainly a debate to be had," said Griffin. "If a family is at risk of, say, cystic fibrosis, and all of their embryos [during IVF] either had the genes for cystic fibrosis or had a chromosome disorder, you might argue – I'm not saying it's my opinion, but you might argue – that they would be good candidates for editing out at least one copy of the offending gene, so they can have healthy children."

The counter-argument, he said, is that those parents could undergo another round of IVF, hoping that it created some healthy embryos, and select one of those if it did. That's called "preimplantation genetic diagnosis", it's already widely used, and Griffin says that it's already helped thousands of couples have healthy children. "But if all [a couple's] embryos are coming up abnormal, they might be a good candidate," said Griffin.

It also doesn't mean that any human embryos will be created and destroyed just for this research.

All embryos used in research in the UK are surpluses from IVF treatments, and would be destroyed anyway if they weren't used in research.

Not everyone is happy about it, though.

Critics warn of a "slippery slope" towards designer babies. "This is the first step on a path that scientists have carefully mapped out towards the legalisation of GM babies," David King, director of Human Genetics Alert, told the Financial Times.

Griffin said that these concerns "aren't necessarily a bad argument", but "it's less important when you have a good regulator, as we do". Nonetheless, he said, "it's very important that we consider it ethically as well as scientifically".

Tom Chivers is a science writer for BuzzFeed and is based in London.

Contact Tom Chivers at

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