He unveiled his research on Monday in Hong Kong to one of the organisers of an global conference on gene editing that is set to begin on Tuesday.
No one knows exactly how He Jiankui, on leave from Southern University of Science and Technology in Shenzhen, did it. Scientists gathered in Hong Kong at an global summit on human genome editing will have to wait until Wednesday to hear He describe his work in more detail.
But experts say his potentially groundbreaking research has not been independently confirmed.
In an e-mail, Annas voiced skepticism of He's claim but said there are a number of ethical concerns if the researcher is, in fact, telling the truth.
Similar work is banned in most countries.
Genetic editing is banned in the USA for ethical reasons, including the risks it poses to DNA that can be passed on to future generations.
In this October 9, 2018 photo, Zhou Xiaoqin adjusts a monitor showing a video feed of a fine glass pipette containing Cas9 protein and PCSK9 sgRNA to an embryo under a microscope at a laboratory in Shenzhen in southern China's Guangdong province.
He says he used gene editing to make babies resistant to infection with HIV, the virus that causes AIDS.
When the twin girls, called Lulu and Nana to protect their privacy, were born, the researchers sequenced the girls' whole genomes again.
Speaking with the AP, Jiankui said that he felt a "strong responsibility that it's not just to make a first, but also make it an example", adding that "society will decide what to do next" whether it will be allowed or forbidden.
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"Grossly premature and deeply unethical", is how noted USA bioethicist Henry Greely of Stanford University characterized the claim.
The university said it would immediately set up an independent investigation team for the matter.
But the university said that He had been on unpaid leave since February and warned the research - which has not been verified - was a 'serious violation of academic. The University and the Department were unaware of the research project and its nature. 2. A university spokesman said the professor had been on a break from teaching since early this year.
In this October 9, 2018 photo, a microplate containing embryos that have been injected with Cas9 protein and PCSK9 sgRNA is seen in a laboratory in Shenzhen in southern China's Guangdong province.
"In this ever more competitive global pursuit of applications for gene editing, we hope to be a stand-out", He and his team wrote in an ethics statement past year. In one twin, all of her cells were edited so as to knock out the CCR5 gene; in the other, only some cells were.
So far the tool has only been used on adults to treat deadly diseases, and the changes only affected that person. Also, some so-called mitochondrial disorders can be addressed by using some genetic material from mom and some from a donor egg, along with dad's sperm. In the US, it's not allowed except for lab research.
Now with this news, all eyes will be on the Second International Summit on Human Genome Editing taking place this week in Hong Kong.
"In that child, there really was nearly nothing to be gained in terms of protection against HIV and yet you're exposing that child to all the unknown safety risks", Dr. Kiran Musunuru, a University of Pennsylvania gene editing expert and editor of a genetics journal, said.
A regulation released in 2016 by the former National Health and Family Planning Commission - now the National Health Commission - requires health institutions to establish ethics committees with authority over biological or medical research involving humans that would have to approve the research.
"If it's true as reported, then it's an extremely premature and questionable experiment in creating genetically modified children", agrees Jeffrey Kahn, a bioethicist at Johns Hopkins Berman Institute of Bioethics attending the Hong Kong summit. All the male subjects had their HIV infections suppressed by HIV medicines that are now easily available all over the world and there are ways to keep the infection from spreading to their babies that already exist and they do not involve and gene altering.
However, one famed geneticist, Harvard University's George Church, defended attempting gene editing for HIV, which he called "a major and growing public health threat".