The scientists expressed anger and doubt over a Chinese geneticist's claim to have edited the genes of the twin girls before birth, while government agencies ordered investigations into the experiment.
A global protest began after genetic scientist He Jiankui said in a video posted on YouTube on Monday that he used the gene-editing tool Crispr-Cas9 to modify a particular gene in two embryos before being placed in the uterus of his mom.
He said the genomes were altered to deactivate a gene known as CCR5, blocking the pathway used by the HIV virus to enter cells.
Some scientists at the International Human Genome Edition Summit, which began Tuesday in Hong Kong, said they were shocked that he had announced his work without following scientific protocols, including publishing his findings in a peer-reviewed journal. Others cited the ethical issues raised by the creation of essentially improved human beings.
Qiu Renzong, a bioethicist and emeritus professor at the Chinese Academy of Social Sciences in Beijing, said his decision to work outside established and supervised scientific protocols could tarnish the reputation of Chinese science.
"Of course it's unethical," Qiu said, after publicly criticizing He's work before the several hundred people present. Qiu said his university, the University of Science and Technology of South Shenzhen, rejected his request to carry out the experiment. This prompted the educated at Stanford He to find a private hospital outside the academic system to apply his research. "Clearly it's a scam," Qiu said. "Maybe he invented a form and found people to sign it."
The National Health Commission of China has ordered the authorities to investigate and verify He's claims. In addition, the Health and Family Planning Commission in Shenzhen, where the scientist worked, said he was exploring ethical issues while reviewing the process followed in He's work.
Feng Zhang, molecular biologist at the McGovern Institute for Brain Research at the Massachusetts Institute of Technology and one of the inventors of Crispr technology, called for results to be released so the scientific community could examine He's work.
"I do not think it was transparently handled, particularly since the first time I heard about it, it was reading in the paper," Zhang said, "and I think transparency is incredibly important, especially for new experimental treatments."
If He's statements are true, the twins will pass the altered DNA to any child they have, which, according to several scientists, would create a series of ethical and medical problems.
"It will have consequences in our lives," said Mohammed Ghaly, a professor of Islam and biomedical ethics at Hamad Bin Khalifa University in Doha, Qatar. "We ended up with big ethical issues … the decision that was made about these twin girls was not made by them, but by someone else. The changes that have happened to them will remain in their children for future generations.
"Are we, as humans, in a position to make such long-term decisions that go beyond our lives and our grandchildren?"
Some scientists were wary of denouncing Him and his work without knowing more details. "Fundamentally, there is nothing different about doing [genome] edits in adult humans against the embryo, "said Eben Kirksey, associate professor of anthropology at Deakin University in Victoria, Australia.
But Kirksey agreed that he raised difficult ethical questions. "I risk creating a new genetically modified elite … that can not get sick, but pass it on to other people."