The claim of a Chinese researcher to create the world's first genetically modified babies is considered "irresponsible" by many scientists.
The researcher's employer, the Southern University of Science and Technology in China, said she knew nothing about the activities. China's government ordered the cessation of work on Thursday.
The researcher, He Jiankui, said he had edited the genetic material or DNA of two recently born girls. He said he had done the gene manipulation to protect babies from HIV infection, the virus responsible for AIDS. He said the trial had "worked safely" and that the two girls were "as healthy as all the other babies."
There was no independent endorsement of He's work and he did not submit any written records of his research.
On Wednesday he defended his work at an international conference in Hong Kong. He also announced a possible second pregnancy with the same procedure.
Scientists condemn the experiment
Scientists quickly condemned the experiments.
David Baltimore is at the California Institute Technology and a director of the conference. He received the Nobel Prize for Medicine in 1975. He called the experiment "irresponsible." Baltimore said it did not meet the guidelines that many scientists had agreed upon before genes could be considered.
Jennifer Doudna is a University of California, Berkeley scientist, and one of the inventors of the CRISPR gene editing tool used in the experiment. She called it "really unacceptable". She told the Associated Press, "I do not think we've heard answers, we still need to understand the motivation for that."
"I feel more disturbed now ," David Liu said of the Harvard University and the Broad Institute of the Massachusetts Institute of Technology. He is the inventor of a version of the gene editing tool. Liu said the experiment is an "example of what you should not do with a promising technology." He hopes that "it will never happen again."
In China, Deputy Minister of Science and Technology Xu Nanping said the experiment. "The line of morality and ethics was respected by the academic community and was shocking and unacceptable."
Why is He in dispute?
In 2017, the US National Academies of Sciences Engineering and Medicine published a report on the processing of human genes The group said gene editing should only be used for research in a lab to learn how to modify embryos.
The academies also said the measure was not suitable for human pregnancies, and if ever allowed should it be used to treat or prevent serious illnesses without better choice be available.
Federal funds can not be used in the United States for gene processing of human embryos. Other countries also have limitations.
People who oppose such experiments say that changes to a person's DNA can be transferred to future generations. They say that genetic modification could harm other genes and affect people who have not accepted the treatment.
Others fear that rich parents are looking for genetic enhancements to produce designer babies.
Is there room for gene editing?
The academies, however, support gene cultivation to improve food production and feed the growing world population.
Researchers use the technology to produce several new crops of crops. These include high-fiber wheat, mushrooms that retain their color, and highly productive tomatoes. They also try to develop corn that resists dry weather and rice that resists soiling.
Other scientists hope to use gene editing to end crops such as the citrus green that infects fruits such as oranges.
In the US a The company Recombinetics wants to raise new types of cows and pigs.
However, many governments are still considering how to oversee genetically modified foods. It is also not clear if people are willing to buy GM food.
I'm Mario Ritter Jr.
Hai Do adapted this story for VOA Learning English based on Associated Press reports. Mario Ritter Jr. was the publisher.
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Words in this story   to prepare something by correcting mistakes or mistakes
Motivation -n. a force or influence that makes one do something
disturbed -adj. Worried and unhappy
abide -v. to act as required