Geneticist He Jiankui, who says he has altered the genes of twin girls born this month, has spoken out about the details of his controversial medical procedure at the Second International Summit on Human Genome Editing at the University of Hong Kong on Wednesday.

He started his speech by apologizing for the “leak” of his work before the conference, and said the Southern University of Science and Technology in Shenzhen, where he works, was unaware of the trial he conducted.

In gene editing, any off-target effects would pose very serious consequences, and extend through the whole body, the researcher admitted, adding that his team carried out embryo off-target detection assessment prior to the trial taking into consideration potential off-target sites mentioned in previous studies.

“We identified one potential off-target in the intragenic region, although we could not identify if it is hereditary or related to editing,” noted He.

The volunteering couple was briefed about the potential off-target site and chose to start a two-embryo pregnancy.

He said the husband is HIV positive, while the spouse is HIV negative. The twin baby girls, born a few weeks ago, are said to be resistant to HIV infection thanks to their edited genes.

No off-target site was observed genome-wide after birth testing, the researcher assured.

“We plan to monitor the twin babies for the next 18 years until they are adult and give their consent for further monitoring,” said He.

The researcher also said another potential pregnancy with gene-edited embryos is currently underway.

Xu Nanping, vice minister of science and technology, said a 2003 regulation permits gene-editing experiments on embryos which are only allowed to remain viable for 14 days, CCTV reported Tuesday night. The ministry will process the case according to law, Xu said.

Meanwhile, Chinese academics and students are concerned about their chances of being accepted to overseas schools and international tie-ups after the controversial experiment.

Chinese Weibo user “Jiandaoshouxuanyuan” who majored in biomedicine, said she is concerned about her ongoing application to a US university after receiving a phone call from her senior who is currently doing biomedical studies at that university’s lab.

“My lab head will be more cautious about enrolling Chinese students. Therefore, you better apply to more programs,” the Weibo user quoted her superior as saying on Tuesday on Weibo.

Researchers who participated in He’s experiment are neither researchers on HIV nor gene-editing experts. It is simply driven by capital, Liu Ying, a research fellow at the Institute of Molecular Medicine of Peking University, told Science and Technology Daily.

“Many laboratories in the world can conduct the experiment, which is not challenging technically. But editing some genes may have unknown consequences while the effectiveness of AIDS resistance impossible to verify,” a doctoral candidate surnamed Zhang, who studies biomedical engineering at Duke University in the US, told the Global Times on Tuesday.

Chu Zhaohui, a research fellow at the Beijing-based National Institute of Education Sciences, told the Global Times on Tuesday that He’s experiment will definitely leave the impression that Chinese scholars do not care about research ethics and are aggressively pushing gene-editing on human beings without considering the ethics involved.

“In addition to applying and getting accepted, Chinese scholars may face greater barriers in seeking cooperation with overseas laboratories on cutting-edge programs,” Chu said.

Besides gene editing, there are other ways to protect yourself from HIV. The following are some knowledge that you may want to know about preventing HIV/AIDS.