New research suggests that Chinese scientist's gene-editing experiment to make children resistant to HIV may have also enhanced their ability to learn and form memories.

Two girls whose genes were modified before birth by a Chinese scientific team using the new editing tool CRISPR could have had their brains affected. New research reported by MIT Technology Review suggests that the alteration introduced into the girls’ DNA to a gene called CCR5, could not only make them smarter, but could also improve their brain recovery after stroke and may be linked to greater success in school.

“The answer is likely yes, it did affect their brains,” said Alcino J. Silva, a neurobiologist at the University of California, Los Angeles, whose lab uncovered a major new role for the CCR5 gene in memory and the brain’s ability to form new connections.

READ MORE: Chinese Scientist Who Created 'Gene-Edited Twins' Under Probe

“The simplest interpretation is that those mutations will probably have an impact on cognitive function in the twins,” said Silva, yet he noted that the exact effect on the girls’ cognition is impossible to predict, thus “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 they used CRISPR to delete CCR5 from human embryos, some of which were later used to create pregnancies. The gene was deleted in order to prevent HIV from entering human blood cells.

The experiment was condemned by other scientists as irresponsible and He is currently under investigation by the Chinese government over concerns about safety and the morality of gene-editing, which have been voiced by both Chinese and international scientists. However, there is no evidence so far that He actually set out to modify the twins’ intelligence. The scientists studying the effects of CCR5 on cognition told MIT Technology Review that the Chinese scientist never reached out to them.

The information about the connection between CCR5 and cognition was first published in a 2016 study, co-authored by Silva, which looked at more than 140 different genetic alterations to find which ones made mice smarter. He was aware of the study, as he acknowledged during a summit of gene editing scientists in Hong Kong that occurred two days after the announcement of the birth of the twins.

“I saw that paper, it needs more independent verification,” He replied when asked about it during a Q&A, adding that he is “against using genome editing for enhancement.”

Silva, however, told MIT Technology Review that He contacted several scientists in the Silicon Valley and elsewhere who had an “unhealthy interest” in designer babies with better brains.

The CCR5 gene can have an effect on many aspects of human life. 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. Another report, published in the journal Cell, claims that people who naturally lack CCR5 recover more quickly from strokes.

“Could it be conceivable that at one point in the future we could increase the average IQ of the population? I would not be a scientist if I said no. The work in mice demonstrates the answer may be yes,” said Silva. “But mice are not people. We simply don’t know what the consequences will be in mucking around. We are not ready for it yet.”