A Chinese scientist claims that he has helped make the world’s first genome-edited babies — twin girls who were born this month. The announcement has provoked shock, and some outrage, among scientists around the world.
He Jiankui, a genome-editing researcher from the Southern University of Science and Technology of China in Shenzhen, says that he implanted into a woman an embryo that had been edited to disable the genetic pathway that allows a cell to be infected with HIV.
In a video posted to YouTube, He says the girls are healthy and now at home with their parents. Genome sequencing of their DNA has shown that the editing worked, and only altered the gene they targeted, he says.
The scientist’s claims have not been verified through independent genome testing or published in a peer-reviewed journal. But, if true, the birth would represent a significant — and controversial — leap in the use of genome-editing. So far these tools have only be used in embryos for research, often to investigate the benefit of using them to eliminate disease-causing mutations from the human germline. But reports of off-target effects in some studies have raised significant safety concerns.
Documents posted on China’s clinical trial registry show that He used the ubiquitous CRISPR-Cas9 genome-editing tool to disable a gene called CCR5, which forms a protein that allows HIV to enter a cell.
Genome-editing scientist Fyodor Urnov was asked to review documents that described DNA sequence analysis of human embryos and fetuses gene-edited at the CCR5 locus for an article in MIT Technology Review. “The data I reviewed are consistent with the fact that the editing has, in fact, taken place,” says Urnov, from the Altius Institute for Biomedical Sciences in Seattle. But he says the only way to tell if the children’s genomes have been edited is to independently test their DNA.
Urnov takes issue with the decision to edit embryos in order to prevent HIV infection. He is also using genome-editing tools to target the CCR5 gene, but his studies are in adult cells, not embryos. He says there are “safe and effective ways” to use genetics to protect people from HIV that do not involve embryo editing. “There is, at present, no unmet medical need that embryo editing addresses,” he says.
“Today’s report of genome editing human embryos for resistance to HIV is premature, dangerous and irresponsible,” says Joyce Harper, who studies women’s and reproductive health at the University College London. Years of research is needed to show that meddling with the genome of an embryo is not going to cause harm, she says. Legislation and public discussion are also needed before genome editing should be used in embryos destined for implantation.
“This experiment exposes healthy normal children to risks of gene editing for no real necessary benefit,” says Julian Savulescu, the director the Oxford Uehiro Centre for Practical Ethics at the University of Oxford.
Making gene-edited babies goes against guidelines released by China’s health ministry in 2003 but does not break any laws.
He says that the couple underwent in vitro fertilization (IVF), a procedure where a woman’s egg is fertilized by a man’s sperm outside the body to form an embryo. When the embryo was just a single cell, He says his team inserted an editing protein that disabled CCR5 before the embryo was implanted into the mother.
The news of the first genome-edited babies comes as researchers in the field gather for a major international meeting on genome editing in Hong Kong from 27-29 November. A key goal of the summit is to reach an international consensus on how genome editing to modify eggs, sperm or embryos, known as germline editing, should proceed. Many scientists in the field believed that it was inevitable that someone would use genome-editing tools to make changes to human embryos that would be implanted into a woman, and had been pushing for the creation of ethical guidelines before the first report emerged.
He only supports the use of genome-editing in embryos in cases that related to disease, and says that genetic tweaks to enhance intelligence or to select for traits such as hair and eye colour should be banned. “I understand my work will be controversial, but I believe families need this technology and I am willing to take the criticism for them,” he says.
Bioethicist Tetsuya Ishii from Hokkaido University also does not think the application of genome editing in embryos to reduce HIV infection is justified. He says babies of HIV positive mother’s can be delivered by caesarean section to avoid transmitting the infection during childbirth.
In the case of the twins, the father is HIV-positive but the mother was not, says He in the YouTube video, meaning there was a very small risk of transmission through the parents. But, in an interview with the Associated Press, He said the goal of the work was not to to prevent transmission from the parents, but to offer couples affected by HIV a chance to have a child that might be protected from a similar fate.
Recent surveys suggest that the public supports genome editing in embryos if it fixes disease-causing mutations. In July, the Nuffield Council on Bioethics, a London-based independent advisory committee, published a survey of 319 people. Nearly 70% of those supported gene-editing if it allows infertile couples to have children, or if it allows a couple to alter a disease-causing mutation in an embryo. A larger survey of 4,196 Chinese citizens released last month reported a similar level of support for modifying genes if the goal is to avoid a disease. But respondents opposed using it to enhance IQ, athletic ability or change skin colour.
This story will be updated throughout the day.