Headlines Suggest That Chinese Gene-Edited Babies May Have Enhanced Intelligence... But Is That Actually True?

Monday, 25 February 2019 - 12:35PM
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Monday, 25 February 2019 - 12:35PM
Headlines Suggest That Chinese Gene-Edited Babies May Have Enhanced Intelligence... But Is That Actually True?
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Pixabay composite.
When Chinese scientist He Jiankui used CRISPR to delete the CCR5 gene in a pair of Chinese twins named Nana and Lulu in an effort to make them immune to HIV, the backlash was swift and furious, with scientists around the world cautioning against the unintended consequences of tinkering with the human genome. "Deleting a single gene," said geneticist Mazhar Adli in an interview with Live Science, "may not only alter how other genes are going to function but also may alter the overall behavior of the cell and the phenotype of [the] organism." Well, according to a recent article in the MIT Technology Review, one of those consequences may be that the twins have had their brains "enhanced." This relatively innocuous term has led to wild interpretations by various media outlets, none of whom we will deign to mention. 


To better grasp how that could happen, it is helpful to have a basic understanding of what the CCR5 gene actually does. CCR5 is responsible for encoding a protein of the same name that serves as a receptor for inflammatory chemokines – signaling proteins – on the surface of white blood cells: the backbone of the immune system. Very basically, scientists believe that CCR5 helps regulate the immune system. In addition to whatever regulatory role CCR5 plays, however, it is also one of two receptors for HIV-1. CCR5 antagonists – chemicals that block CCR5 – prevent HIV from attaching to them, thus preventing the virus from taking hold in the body. Scientists have also found that CCR5 levels surge in the brain after a stroke as part of the inflammatory response to trauma: as such, recovery from such an event is delayed. In a recent article published in Cell, UCLA researchers revealed that not only did stroke patients with a loss-of-function mutation in the CCR5 gene (known as CCR5-Δ32) exhibit "greater recovery of neurological impairments and cognitive function," treating rodent (mice) stroke victims with Maraviroc, a CCR5 antagonist, led to faster recovery. The mechanism of action has to do with neural plasticity: the ability for the brain to generate connections. "When you suffer a stroke, part of your brain dies, severing those cells' connections with neurons in other regions. That's why stroke patients often suffer paralysis or lose speech," said UCLA neuroscientist and lead study author Dr. S. Thomas Carmichael in a press release. "When CCR5 is missing or blocked, neurons can make new connections and rewire the brain, enabling patients to regain some lost function." Even more promising is earlier research by a group of international scientists that found that "decreasing CCR5 function" in mice led to enhanced memory and learning and declared CCR5 a "suppressor for cortical plasticity and hippocampal learning and memory."


In addition to all this, MIT reported that Carmichael's team also found a link between educational success and decreased CCR5. "We are the first to report a function of CCR5 in the human brain," Carmichael said, "and the first to report a higher level of education." This quote seems to have driven the majority of headlines suggesting the possibility of genetically-altered, hyperintelligent Chinese twins. Having perused the original study, however, it seems that Carmichael is referencing a group of stroke patients with the previously mentioned CCR5-Δ32 mutation who "exhibited greater recovery of neurological impairments and cognitive function" than the CCR5-active patients. 


To be clear: before you go trying to conduct CRISPR experiments on yourself, please not that we could not find any peer-reviewed literature directly linking the CCR5-Δ32 mutation or CCR5 suppression to increased human intelligence. 


One would think that if such genetic modifications were possible, they'd be all the rage in China, where genetic testing for intelligence seems to be on the rise, but what remains murky is whether or not Jiankui's experiment was even successful. As Stat News reported shortly after the experiment began making headlines, the edits may have been incomplete, which would have left the twins with their CCR5 receptors at least somewhat intact. Even so, at least one scientist believes that there would be some kind of brain alteration. "The answer is likely yes, it did affect their brains," UCLA neurobiologist Alcino J. Silva told Technology Review. "The simplest interpretation is that those mutations will probably have an impact on cognitive function in the twins." Silva's reticence in stating whether or not that "impact" would be positive or negative stems from the unpredictability of these experiments. "We simply don't know what the consequences will be in mucking around," Silva said. "We are not ready for it yet."






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