Professor He said there had been "another potential pregnancy" involving a second couple, but it is unclear whether that pregnancy is still ongoing. Harmonicare Women's and Children's Hospital, where He said he received ethical approval for his research, denied they had given him the go-ahead and filed a report with police. Two babies, a pair of twin girls, have already been born and more are allegedly on the way. "When you balance the minimal benefit in terms of protection against HIV, compared to increased chance of dying from a fairly common infection like the flu, I don't think that works out on balance".
More than 100 scientists, most in China, said in an open letter on Tuesday that 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.
And he insisted that the parents of the twins and seven other couples who had participated in his research were fully informed of the risks involved, and that they understood what was being done to their embryos.
"I think the failure was his, not the scientific community", Charo said.
He added that the experiment would "be considered irresponsible" because it did not meet criteria many scientists agreed on several years ago before gene editing could be considered. He felt especially proud of being able to restore lost faith in the parents of the twins, the father of whom is believed to carry HIV.
Even more concerning, Musunuru says, is that tests conducted on the newborns, and when they were embryos, suggest both girls may have mosaicism, which means the edits worked on only some of their cells.
Outside scientists and ethicists slammed the experiment for being medically unnecessary, because the babies wouldn't have been born infected with the virus, which can also be prevented with existing, low-risk interventions. Other scientists have said the procedure was unnecessary and unsafe. Although he still hasn't published any real evidence, scientists across the world were quick to condemn the ethically dubious claims, describing the experiment as "deeply concerning", "shocking", and "monstrous".
He said that "the clinical trial was paused due to the current situation". Although his appearance had been previously scheduled, Lovell-Badge said He had earlier "sent me the slides he was going to show in this presentation and it didn't include anything that he is going to talk about today".
Gene editing occurred during IVF, first sperm was washed, a single clean sperm was placed into a single egg to create an embryo, then the gene editing tool was added.
He admitted at a gene-editing conference in Hong Kong on Wednesday he had already initiated another pregnancy, although it was too soon to tell if it would go to full term. He has been on leave from the university since February, and the school said in a statement it was unaware of his work in humans and condemned it.