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He Jiankui
Chinese researcher He Jiankui addresses the Second International Summit on Human Genome Editing in Hong Kong. (National Academies via Twitter)

The Chinese researcher behind a controversial experiment to produce gene-edited children took the stage at a Hong Kong conference to explain his work, and acknowledged that the international outcry has brought a halt to the experiment.

“The clinical trial was paused due to the current situation,” He Jiankui, a biomedical researcher at the Southern University of Science and Technology in Shenzhen, said today at the Second International Summit on Human Genome Editing.

The university says He (pronounced “Heh”) has been on unpaid leave since January, and today Chinese news outlets reported that his lab on campus has been shut down and sealed off for investigation.

He Jiankui says that he and his colleagues undertook the unprecedented experiment with the aim of helping HIV-positive fathers give birth to HIV-free children. As a result of the trial, twin girls known by the pseudonyms Lulu and Nana were born in recent weeks to an HIV-positive father known as Mark and an HIV-free mother called Grace, He reported this week.

The girls developed from embryos that had been fertilized in vitro and genetically engineered using a technique known as CRISPR, He said. The technique sought to disable a gene known as CCR5 that plays a role in facilitating the spread of the HIV virus to healthy cells. DNA tests suggest the strategy was mostly effective for one of the twins, but less so for the other, according to He’s report.

There’s been no outside confirmation of the experiment’s results, but He said that they’ve been submitted to a scientific journal for review.

“For this specific case, I feel proud, actually,” He said. “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.”

Other researchers noted, however, that there are far less controversial methods for protecting children from their parents’ HIV infection. One method, which is called sperm-washing, was used during the in-vitro fertilization phase of the trial.

In all, seven couples were enrolled in the clinical trial, and implantation of the gene-edited embryos resulted in one other “potential pregnancy,” He said. But in response to a follow-up question, He acknowledged that it was a chemical pregnancy, a term that can apply to an early-stage miscarriage.

He faced widespread criticism over the circumstances of the experiment. Such experiments would be illegal in many countries, including the United States. A statement issued by Francis Collins, director of the National Institutes of Health, touched several bases:

“The project was largely carried out in secret, the medical necessity for inactivation of CCR5 in these infants is utterly unconvincing, the informed consent process appears highly questionable, and the possibility of damaging off-target effects has not been satisfactorily explored.  It is profoundly unfortunate that the first apparent application of this powerful technique to the human germline has been carried out so irresponsibly.”

Collins said the episode pointed up the urgent need for developing binding international consensus on setting limits to such research. “Should such epic scientific misadventures proceed, a technology with enormous promise for prevention and treatment of disease will be overshadowed by justifiable public outrage, fear and disgust,” he said.

Further statements of disapproval are expected to come out of the Hong Kong meeting, and multiple investigations are underway in China and in the United States.

The die is cast, however, at least with respect to Lulu and Nana. Southern University’s He said the twin girls’ health would have to be monitored for the next 18 years, and beyond that into adulthood if they give their consent. In the near term, the researcher said blood tests would be conducted to monitor for any signs of HIV infection, and the girls would also be checked for any off-target genetic effects.

Lulu and Nana could face other health concerns, even if the experiment worked perfectly: The same mutation in the CCR5 gene that reduces the risk of HIV has been found to heighten the risk for infection by flu viruses and West Nile virus.

He Jiankui expressed no regrets about conducting the study, but apologized for the way it came to light. “These results leaked unexpectedly,” which meant the full data could not get its first presentation in a scientific venue, He said.

The last question that He was asked at the Hong Kong meeting touched on the personal angle: Would he have gone ahead with such an experiment if it involved his family?

“If my baby may have the same situation, I would try first,” he said.

More on the controversy:

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