Chinese scientist Jiankui He on Wednesday faced questions from the media and other researchers for the first time in public since revealing his team.
With some hesitation, He told the crowd at the second International Summit on Human Gene Editing in Hong Kong that more babies modified by the revolutionary gene-editing tool CRISPR could be on the way.
"There is another potential pregnancy," He said when pressed on stage after presenting his work at the summit. But he cautioned the pregnancy is at a very early stage.
The scientist had already been granted a slot to speak at the summit, but the slides he sent along to the event's organizers beforehand said nothing of carrying gene-edited human embryos to term. Rather, the story broke via MIT Technology Review and He's own YouTube videos just before the summit.
So when He's slot came up Wednesday, he was allowed to present the work that the many photographers, reporters and scientists in the room had already read about in the news.
Robin Lovell-Badge, a biologist at The Francis Crick Institute, introduced He with the odd caveat that he reserved the right to cancel the session if there was too much disruption.
Many scientists have come forward in the past 48 hours to condemn the use of CRISPR/Cas9 on humans because of the many fraught ethical questions involved. Shenzhen's Southern University of Science and Technology, where He works, has also .
After a bizarre minute in which Lovell-Badge stood silent at the podium while summit staff presumably tried to locate the just-introduced He, the controversial scientist finally appeared and took the stage to the deafening roar of camera shutters. The constant onslaught of flashes and shutters actually required an interruption and announcement from organizers to knock it off.
He's presentation was technical and difficult to decipher for the layperson. The questions that followed were tense but calm and cordial.
The basic gist of the study is that seven couples volunteered to have embryos from their egg and sperm genetically modified in the hopes the resulting children would be resistant to HIV. Each father in the trial was HIV positive and each mother was HIV negative.
The announcement that broke earlier this week was that twin girls, dubbed Lulu and Nana, had been born to one of the sets of parents with the desired genetic modification.
"The plan is to monitor the twins' health for the next 18 years with the hope they will consent as adults for continued monitoring and support," He said at the conclusion of his prepared remarks.
The news of the twins' births rocked the scientific community this week and CalTech biology professor David Baltimore, a Nobel laureate who also chairs the summit organizing committee, took the unusual measure of prefacing the question and answer session with He by taking a moment to call his work "irresponsible."
"I don't think it has been a transparent process. We only found out about it after it happened and after the children were born. I personally don't think that it was medically necessary," Baltimore said from the podium as He looked on from the other side of the stage. "I think there has been a failure of the scientific community because of a lack of transparency."
Baltimore stressed he was speaking only on behalf of himself, adding that safety issues and "broad societal consensus" have not yet been worked out on the question of editing human embryos.
He was elusive at first when asked if there were other genetically modified pregnancies in progress, saying the trial was "paused due to [the] current situation."
When later pressed again, he admitted there was another potential pregnancy.
CRISPR pioneer David Liu from the Broad Institute was the first to ask a question from the audience. Liu also said he didn't see the medical need for the procedure given that He used other measures, including "sperm washing," to ensure the HIV-positive father did not pass the virus to the mother or offspring. Sperm washing makes sure there's no contaminated semen sticking to the sperm that could then contaminate the embryo.
He responded that the trial was not just for the parents of Lulu and Nana, but for millions of children in need of protection from HIV, for which there is currently no vaccine. He talked about visiting villages in China where 30 percent of children are HIV positive.
"They even have to give their children to relatives or uncles to raise just to prevent the (risk) of transmission," He said.
As for Lulu and Nana, it may be some time before the world gets to meet them. He said they will likely remain anonymous due to laws in China around revealing the identity of people with HIV.
It's certainly not the last we'll hear from He, however.
He said his research has been submitted to peer-reviewed journals for future publication.
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