CRISPR is a powerful technique for editing DNA CARLOS CLARIVAN/SCIENCE PHOTO LIBRARY

This week, news broke of the birth of the first two babies to have had their genes altered as embryos, a genetic change they could pass on to their own children. The use of the powerful gene-editing tool CRISPR was widely thought to not yet be ready for use in human embryos for safety reasons. The technique was used to edit a gene so that future children may be resistant to some strains of HIV. The scientist, He Jiankui, has now presented his work at the Second International Summit on Human Genome Editing in Hong Kong. CRISPR expert Helen O’Neill, of University College London, was there.

What is the atmosphere like at the Summit?

It’s very surreal. Most of us landed on Monday and turned our phones on to a complete barrage of emails saying “Have you seen the news?” Jiankui He didn’t show up at the conference until today, [Wednesday, when he was due to talk]. There was so much press this morning you could barely hear him. He was ushered in and then ushered away at the end.


What was He like?

He came in very, very humbled, like a scolded child. I think he’s possibly afraid that he’s going to face charges. In some countries you could go to jail for this. At the moment Chinese law says you can’t do it but there’s no penalty. I don’t know whether he’s going to be made an example of.

Do you believe He has done what he claims?

Among the scientific community we’re very sure. He gave quite an impressive presentation on quite extensive and thorough research that he had done both in animal and human embryos. The initial shock meant people went “Surely not – he has to prove it.” But I never had any doubt.

Did he reveal any more interesting details?

It was afterwards in the question session that the juicy things came out that people wanted to know. Bit by bit you were getting more information that was more shocking. The fact that he had partly funded it himself. Almost incidentally, when he was asked about any other pregnancies, he said “Er…yeeees there is.” Robin [Lovell-Badge, who was chairing the talk] clarified that it was a very early pregnancy.

Why is gene-editing embryos so shocking, when people are already using CRISPR on adults?

Primarily because if something goes wrong you can’t stop it. And we have no way of knowing what effect it will have on the next generation. If he’d shown some transparency there would be more trust in what he was doing. But he’s been off-radar for months. He’s on unpaid leave, he’s doing this on his own.

Why do you think he targeted a gene that affects HIV risk?

His choice of gene was a terrible one. There’s a layer of almost prejudice to mutating a gene so you’re not susceptible to HIV. If it was a life-threatening disorder that has no other treatment, people would have found it more justifiable. The impression among the scientific community is that this was the low-hanging fruit, because there had been a lot of research into [this gene].

How much of a red line has been crossed?

The red line is miles behind us now. It’s no longer in sight.

Read more: CRISPR scientist says another woman is pregnant with an edited embryo