He also thanked his university, the Southern University of Science and Technology in China, but noted that they were "unaware of the study's conduct".
He's work was widely criticized this week by peer researchers and ethicists as a rogue demonstration of a gene editing tool called CRISPR-Cas9, which has opened up a world of new possibilities in biomedical research in recent years.
But until this week, such debates were largely theoretical, because no one was known to have established a pregnancy from a genetically-edited human embryo.
"For this specific case, I feel proud".
U.S, laws prohibit scientists from pursuing such research, Francis Collins, director of the National Institutes of Health, told STAT. He claims all of his tests of the girls showed they were completely healthy and normal. Communications department officials at the school did not respond to requests to discuss the investigation into He's research activities. There is tremendous suffering particularly in the developing world both from the disease and from the stigma surrounding it, he noted several times.
Tampering with genes of human embryos is outlawed in many countries.
"They need this protection since a vaccine is not available", He said.
Mr Baltimore said: "I personally don't think that it was medically necessary".
Baltimore added, "I don't think it has been a transparent process".
Since then several scientists have reviewed the material that He Jiankui provided to the AP, tests so far are suggested to be insufficient to say editing worked to rule out harm, noting evidence of editing being incomplete, and at least one twin appears to be a patchwork of cells with various changes, nearly as if not editing at all. Other scientists have said the procedure was unnecessary and risky. Its risks are unknown, and leading scientists have called for a moratorium on its use except in lab studies until more is learned.
Facing a packed auditorium of scientists and members of the media, He also acknowledged that he had not made his university in China aware of the research he was doing.
Instead, it acknowledged that the field was moving toward a future where the procedures would be widely researched in clinical trials, and that researchers needed a rigorous framework to set ethical standards and guidelines.
The researcher acknowledged during his talk that he had seen the mouse data on CCR5 but dismissed it.
Dr. Robin Lovell-Badge, who moderated the Wednesday session, said in an email that "it would have been hard to have sufficient security" for a second talk. "That should be banned".
Chinese authorities have ordered He to cease the experiments and said his work is being investigated by the university. On Nov. 26, the University released a statement saying that He had been on unpaid leave since February, and that they were "deeply shocked" by the news of the research.
The Second International Summit on Human Genome Editing, taking place this week in Hong Kong, was supposed to be a gathering of researchers and medical professionals for the goal of furthering the scientific and ethical standards of genetic modification.