HONG KONG • Chinese scientists who claim to have created the first genetically edited babies have defended a highly controversial procedure, but said the trial would be stopped after international condemnation.
Dr He Jiankui yesterday said at a packed Hong Kong biomedical conference that he was "proud" of having succeeded in changing the DNA of twin girls born to HIV-positive fathers – a real medical breakthrough.
But the details of the experiment, which has not been independently verified, triggered an immediate reaction, with experts denouncing Dr He's work as an "ethics"
Said Dr He: "The clinical trial was suspended because of the current situation. For this particular case, I feel proud, actually, I feel most proud."
The university professor said twin girls, born a few weeks ago, changed their DNA to prevent them from contracting HIV. Eight volunteer couples – HIV-positive fathers and HIV-negative mothers – signed up for the trial, with one breaking before being stopped.
He said there was "another potential pregnancy" involving a second partner but when asked further, he said it was a chemical pregnancy – a term that refers to early miscarriages.
Experiments have prompted fierce debate among scientists about the risks involved. Experts say editing human embryos can create unwanted mutations in other areas, known as "off-target effects", which can have an impact throughout life.
Dr He, responding to questions from the audience, said: "Volunteers were told about the risks posed by the potential for off-target, and they decided to plant." He also said he personally paid for most of the patient's medical expenses, and that his university in Shenzhen city in southern China was unaware of the research.
The South University of Science and Technology distanced itself from Dr He, saying that he had been on leave without pay since February and had "violated academic ethics".
The organizer of the Second International Summit on Editing the Human Genome, where Dr. He spoke yesterday, also said they did not know about his work.
Conference moderator Robin Lovell-Badge said Dr He's trial was a "step back" for the science industry, but described the birth of babies as "important" anyway.
He said: "This is an example of an approach that is not careful enough and careful and proportionate. Obviously, however, this is an important point in history."
Summit Chair David Baltimore, a Nobel winner, said there was "a failure of self-regulation by the scientific community".
Dr He, who was educated at Stanford University, said the twins' DNA was modified using CRISPR, a technique that allows scientists to remove and replace DNA strands with precise precision.
Gene editing is a potential improvement for inherited diseases but is very controversial because changes will be passed on to future generations, and ultimately can affect the whole gene pool.
In many countries, editing of human DNA is tightly controlled.
Dr He has not released the identity of the trial participants.
University of Massachusetts Lowell Assistant Professor Nicholas Evans wrote on Twitter: "Don't get me wrong, privacy is very important here. But I'm afraid no one can independently support this story."