Organisers of a conference that has been upended by gene-edited baby revelations are holding their breath as to what the controversial scientist at the center of "breakthrough" will say when he takes the stage.
Chinese scientist He Jiankui is due to speak to the world's first genetically-edited babies.
In a video posted on YouTube, university professor He said that the twin girls, born a few weeks ago, had had their DNA altered to prevent them from contracting HIV.
The move – which would be a medical first if the prompted a heated debate among the scientific community, with many of the raising concerns over the lack of verified data and exposing healthy embryos and children to gene editing.
Organisers of the Second International Summit on Human Genome Editing, which opened Tuesday, also appeared to be unaware of He's work.
Biologist and summit chair David Baltimore told AFP on the sidelines of the conference that he had "no idea whether he is reliable or not".
"I have not seen any of the research and I do not know what he is planning to claim," said Baltimore.
Keynote speakers were mobbed by the press on the opening day, after the conference drew international attention on the baby's revelations.
John Christodoulou, chair of genomic medicine at the University of Melbourne, said it seemed the research had "bypassed the usual ethical regulatory processes".
"But if what he has done is to edit human embryos, and for them to be carried through to birth … there is a real risk of so-called off-target effects," he added.
"The technology can create mutations or break chromosomes in other areas apart from where we're hoping it's being targeted."
Margaret Sleeboom-Faulkner from the University of Sussex told AFP Tuesday that "it will be very wise to make sure that this should not happen as a standard".
He, who was educated at Stanford University and works from a lab in the southern Chinese city of Shenzhen, said the twins' DNA was modified using CRISPR, a technique which allows scientists to remove and replace a strand with pinpoint precision.
Gene editing is a potential fix for healing diseases but it is highly controversial because the changes will be passed down to future generations and could eventually affect the entire gene pool.
– 'Immediate investigation' –
Qiu Renzong, formerly the vice president of the Chinese Ministry of Health's Ethics Committee, told reporters at the gene editing conference that lax regulations in China mean that scientists who break the rules often face no punishment, and think of the ministry as being "without teeth ".
He has been to join a panel discussion on Wednesday and talk on developing on human gene editing.
But as sceptical experts cast doubt over the alleged breakthrough, his research came under fire of a number of other fronts too.
China's National Health Commission ordered an "immediate investigation" into the case, the official Xinhua news agency reported, while the Shenzhen hospital meant to have been approved by the research program denied its involvement.
The university where he works also distanced himself – saying he was on unpaid leave since February – and called his claims a "serious violation of academic ethics and norms".
He did not respond to a request for comment from AFP.
The issue of editing human DNA is highly controversial, and in many countries is tightly controlled.
But this is not the first time Chinese researchers have experimented with human embryo technology.
Last September, scientists at Sun Yat-sen University used an adapted version of gene-editing to correct a disease-causing mutation in human embryos.
There is also a history of fraud within China's academic community – including a scandal last year that led to the withdrawal of 100 "compromised" academic papers.
A joint statement from the 100 scientists in China criticized He Jiankui's claims and called them a "great blow to the global reputation and development of biomedical research in China".