(Adds geneticist due to speak in Hong Kong on Wednesday)
SHANGHAI, Nov 27 (Reuters) - More than 100 scientists, most of them in China, have condemned as "crazy" and unethical altering human genes after a geneticist claimed he had changed the genes of twin girls to create the first gene-edited babies.
In an open letter circulating online, the scientists said the use of CRISPR-Cas9 technology to edit the genes of human embryos was risky, unjustified and harmed the reputation and development of the biomedical community in China.
In videos posted online, scientist He Jiankui defended what he claimed to have achieved, saying he had performed the embryonic gene editing to help protect the babies born this month from infection with HIV, the virus that causes AIDS.
"The biomedical ethics review for this so-called research exists in name only. Conducting direct human experiments can only be described as crazy," the scientists said in their letter, a copy of which was posted by the Chinese news website the Paper.
"Pandora's box has been opened. We still might have a glimmer of hope to close it before it's too late," the approximately 120 scientists said in the Chinese-language letter.
Yang Zhengang, a Fudan University professor, told Reuters he signed the letter because gene editing was "very dangerous".
He, who is due to speak at a summit on human genome editing at the University of Hong Kong on Wednesday, did not respond to a Reuters request for comment.
The Southern University of Science and Technology, where He holds an associate professorship, said it had been unaware of the research project and that He had been on leave without pay since February.
China's National Health Commission said on Monday it was "highly concerned" and had ordered provincial health officials "to immediately investigate and clarify the matter".
The government's medical ethics committee in the city of Shenzhen, in southern China, said it was investigating the case, as was the Guangdong provincial health commission, according to Southern Metropolis Daily, a state media outlet.
CRISPR-Cas9 is a technology that allows scientists to essentially cut-and-paste DNA, raising hope of genetic fixes for disease. However, there are also concerns about its safety and ethics.
The committee organising the Hong Kong conference where He is due to speak - the Second International Smmit on Human Genome Editing - said in a statement on Monday it had only just been informed of He's work on the genes of the twin girls.
"Our goal is to help ensure that human genome editing research be pursued responsibly," the committee said.
(Reporting by John Ruwitch in Shanghai; Additional reporting by Holly Chik and Anne Mare Roantree in Hong Kong Editing by Darren Schuettler, Robert Birsel)
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