He Jiankui of the Southern University of Science and Technology in Shenzhen, China, addressed hundreds of scientists gathered at an global gene-editing summit in Hong Kong that has been rocked by ethical questions swirling around his research. "That will help more people in need", he said.
Feng Zhang, one of the founders of the CRISPR Cas9 technology used in He's experiment and a professor at MIT, told Caixin that DNA editing has a long way to go before being used in embryos. "Yes, of course it's an HIV-infected father, a non-HIV infected mother, so certainly transmission to the baby is a concern, but there are other ways to do this".
Qiu Renzong, formerly the vice president of the Chinese Ministry of Health's ethics committee, told reporters at the 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 also said the university where he works had been "unaware of the study's conduct".
The ethics of the procedure are also complicated by the fact that targeting specific segments of DNA may not be fully precise or could carry side effects that are hard to predict.
The second potential pregnancy is in a very early stage and needs more time to be monitored to see if it will last, Dr He said.More news: Google's cellular service gets rebranded, offers support for iPhones
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The revelation was stunning, not only because the genomics field had declared a voluntary worldwide moratorium on editing embryos three years ago, but also because it came before He's work was peer-reviewed or published in a journal. Now, He is defending his work even as another scientist, this time in the US, comes under investigation for his role in the research.
"This is probably the worst gene you would choose" to test in pregnancy because it doesn't fix a disease the children were destined to get, said Shoukhrat Mitalipov of the Oregon Health & Science University, who in laboratory-only experiments studies how to repair gene defects in embryos.
"I must apologise this result was leaked unexpectedly", He said of the apparent breakthrough "The clinical trial was paused due to the current situation", he added.
He did not name those people. "[An] HIV vaccine is not available", he said.
When asked if he had considered the implications of carrying out the procedure on behalf of two unborn girls with potentially unknown physical or emotional consequences, He said he could not answer the question. He talked about visiting villages in China where 30 percent of children are HIV positive.
"I feel a strong responsibility not to just make it first but to make it as an example", He said in a video interview with Associated Press on Monday, when he released his research. "I feel proudest because Mark lost hope for life, but with this protection, he sent a message saying he will work hard, earn money, and take care of his two daughters and his wife". "We don't know if this work is real or fake".
"The volunteers were informed of the risk posed by the existence of one potential off-target and they made a decision to implant", He said Wednesday, as he was bombarded with questions about the trial.
Born in China's Hunan Province, He graduated from the University of Science and Technology of China in 2006 and pursued a PhD at Rice and postdoctoral research at Stanford.