Antonio Regalado, MIT Technology Review, February 21, 2019
The brains of two genetically edited girls born in China last year may have been changed in ways that enhance cognition and memory, scientists say.
The twins, called Lulu and Nana, reportedly had their genes modified before birth by a Chinese scientific team using the new editing tool CRISPR. The goal was to make the girls immune to infection by HIV, the virus that causes AIDS.
Now, new research shows that the same alteration introduced into the girls’ DNA, to a gene called CCR5, not only makes mice smarter but also improves human brain recovery after stroke, and could be linked to greater success in school.
“The answer is likely yes, it did affect their brains,” says Alcino J. Silva, a neurobiologist at the University of California, Los Angeles, whose lab has been uncovering a major new role for the CCR5 gene in memory and the brain’s ability to form new connections.
“The simplest interpretation is that those mutations will probably have an impact on cognitive function in the twins,” says Silva. He says the exact effect on the girls’ cognition is impossible to predict, and “that is why it should not be done.”
The Chinese team, led by He Jiankui of the Southern University of Science and Technology in Shenzhen, claimed it used CRISPR to delete CCR5 from human embryos, some of which were later used to create pregnancies. HIV requires the CCR5 gene to enter human blood cells.
The experiment has been widely condemned as irresponsible, and He is under investigation in China. News of the first gene-edited babies also inflamed speculation about whether CRISPR technology could one day be used to create super-intelligent humans, perhaps as part of a biotechnology race between the US and China.
Although He never consulted the brain researchers, the Chinese scientist was certainly aware of link between CCR5 and cognition. It was first shown in 2016 by Zhou and Silva, who found that removing the gene from mice significantly improved their memory. The team had looked at more than 140 different genetic alterations to find which made mice smarter.
Whatever He’s true aims, evidence continues to build that CCR5 plays a major role in the brain. Today, for example, Silva and a large team from the US and Israel say they have new proof that CCR5 acts as a suppressor of memories and synaptic connections.
According to their new report, appearing in the journal Cell, people who naturally lack CCR5 recover more quickly from strokes. What’s more, people missing at least one copy of the gene seem to go further in school, suggesting a possible role in everyday intelligence.
The discoveries about CCR5 are already being followed up in drug trials on both stroke patients and people with HIV, who sometimes suffer memory problems. In those studies, one of which is under way at UCLA, people are being given an anti-HIV drug, Maraviroc, which chemically blocks CCR5, to see if it improves their cognition.