HONG KONG (Reuters) - A Chinese scientist at the center of an ethical storm over what he claims are the world’s first genetically edited babies said on Wednesday he is proud of his work and revealed there was a second “potential” pregnancy as part of the research.

He Jiankui, an associate professor at Southern University of Science and Technology in Shenzhen, China, addressed a packed hall of around 700 people attending the Human Genome Editing Summit at the University of Hong Kong.

“For this case, I feel proud. I feel proudest,” He said, when challenged by several peers at the conference.

Asked whether there were any other edited gene pregnancies as part of his trials, He said there was another “potential” pregnancy and replied “yes” to a follow-up question as to whether it was a “chemical pregnancy”, which refers to an early-stage miscarriage.

It was unclear whether the pregnancy had ended or not.

He, who said his work was self-funded, shrugged off concerns that the research was conducted in secrecy, explaining that he had engaged the scientific community over the past three years.

“This study has been submitted to a scientific journal for review,” He said. He did not name the journal and said his university was unaware of his study.

In videos posted online this week, He said he used a gene-editing technology known as CRISPR-Cas9 to alter the embryonic genes of twin girls born this month.

He said gene editing would help protect the girls from infection with HIV, the virus that causes AIDS.

Slideshow ( 3 images )

But scientists and the Chinese government have denounced the work that He said he carried out, and a hospital linked to his research suggested its ethical approval had been forged.

The conference moderator, Robin Lovell-Badge, said the summit organizers were unaware of the story until it broke this week.

CRISPR-Cas9 is a technology that allows scientists to essentially cut and paste DNA, raising hope of genetic fixes for disease. However, there are concerns about safety and ethics.

(Graphic explaining CRISPR gene editing technique, tmsnrt.rs/2ReKG1R)

The Chinese Society for Cell Biology in a statement on Tuesday strongly condemned any application of gene editing on human embryos for reproductive purposes and said that it was against the law and medical ethics of China.

More than 100 scientists, most in China, said in an open letter on Tuesday the use of CRISPR-Cas9 technology to edit the genes of human embryos was dangerous and unjustified. “Pandora’s box has been opened,” they said.

INFORMED CONSENT

He, who said he was against gene enhancement, said eight couples were initially enrolled for his study while one dropped out. The criteria required the father to be HIV positive and the mother to be HIV negative.

Slideshow ( 3 images )

Scientists at the conference pressed He to prove that those taking part in the trial were aware of all the risks involved in the process.

He said that all the participants had a “good education background” and went through two rounds of discussions with him and his team.

A 23-page English translation of an informed consent form for the potential mother said that the costs of the procedure covered by the team would be up to 280,000 yuan ($40,200) per couple.

The consent form mentions multiple risks, but there is little detail on potential complications of the gene-editing process itself, including for the child. It does not mention that such an experiment has never been done before.

David Baltimore, President Emeritus and the Robert Andrews Millikan Professor of Biology at the California Institute of Technology, spoke after He’s speech, saying it was irresponsible to have proceeded until safety issues were in order.

“I don’t think it has been a transparent process. Only found out about it after it happened and the children were born,” Baltimore said.

He Jiankui said his results could be used for millions of people with inherited diseases. He said he would monitor the two newborns for the next 18 years and hoped they would support continued monitoring thereafter.

Shenzhen Harmonicare Medical Holdings Limited 1509.HK, named as being involved in He's project in China's clinical trial registry, sought to distance itself by stating the hospital never participated in any operations relating to the gene-edited babies and no related delivery had taken place.

In a statement to the Hong Kong stock exchange on Tuesday, the group said preliminary investigations indicated the signatures on the application form circulated on the internet are “suspected to have been forged, and no relevant meeting of the Medical Ethics Committee of the hospital in fact took place”.

The Guangdong province Health Commission announced on its website on Wednesday that it and Shenzhen city had set up a joint team to investigate the case.