Home Sciences They discover how a neuronal genetic mutation causes greater intelligence

They discover how a neuronal genetic mutation causes greater intelligence


German researchers have discovered that a genetic mutation that causes vision loss simultaneously increases intelligence because it increases communication between neurons.

When genes mutate, they can lead to serious diseases of the human nervous system. Researchers from the University of Leipzig and the University of Würzburg have used fruit flies to show how, in addition to the negative effect, the mutation of a neuronal gene can have a positive effect, namely a higher IQ in humans. They have published the discovery in the prestigious magazine “Brain”.

Synapses are the contact points in the brain through which nerve cells “talk” to each other. Alterations in this communication lead to diseases of the nervous system, since altered synaptic proteins, for example, can disrupt this complex molecular mechanism. This can cause mild symptoms, but also very serious disabilities in those affected.

The interest of neurobiologists, Tobias Langenhan Y Manfred Heckmanfrom Leipzig and Würzburg respectively, woke up when they read in a scientific publication about a mutation that damages a synaptic protein.

At first, affected patients attracted the attention of scientists because the mutation caused them to lose their sight. However, the doctors noted that the patients also had above-average intelligence.

“It is very rare that a mutation causes an improvement rather than a loss of function,” says Langenhan, professor and holder of a chair at the Rudolf Schönheimer Institute for Biochemistry at the Faculty of Medicine.

fruit flies

The two neurobiologists have been using fruit flies to analyze synaptic functions for many years. “Our research project was designed to insert the patients’ mutation into the corresponding gene in the fly and use techniques such as electrophysiology to test what happens to the synapses. We hypothesized that the mutation makes patients so smart because it improves communication between neurons involving the damaged protein,” explains Langenhan.

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“Of course, you can’t make these measurements at synapses in the brains of human patients. You have to use animal models for that,” she adds, specifying: “75 percent of the genes that cause disease in humans also exist in fruit flies.”

First, the scientists, together with Oxford researchers, showed that fly protein called RIM it has a molecular appearance identical to that of humans. This was essential to be able to study changes in the human brain in the fly.

In the next step, the neurobiologists inserted mutations into the fly’s genome that looked exactly like they do in sick people. They then took electrophysiological measurements of synaptic activity.

“In fact, we observed that the animals with the mutation showed a much higher transmission of information in the synapses. This surprising effect on fly synapses is probably found in the same or similar way in human patients, and could explain their higher cognitive performance, but also their blindness,” Professor Langenhan concludes.

More neurotransmitters

The scientists also discovered how increased transmission occurs at synapses: Molecular components in the transmitting nerve cell that trigger synaptic impulses move closer together as a result of the effect of the mutation, leading to increased neurotransmitter release.

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A novel method, super-resolution microscopy, was one of the techniques used in the study. “This gives us a tool to look at and even count individual molecules and confirms that the molecules in the activation cell are closer together than normal,” Langenhan says.

“The project beautifully demonstrates how an extraordinary model animal like the fruit fly can be used to gain a very deep understanding of human brain disease. Animals are genetically very similar to humans. It is estimated that 75 percent of the genes related to diseases in humans are also found in the fruit fly”, explains Professor Langenhan.

He adds that they will continue to investigate the subject at the Faculty of Medicine: “We have started several joint projects with human geneticists, pathologists and the team of the Integrated Center for Research and Treatment (IFB) Adiposity Diseases, based at the Leipzig University Hospital, they are studying disorders of brain development, the development of malignant tumors and obesity. Here, too, we will insert disease-causing mutations into the fruit fly to replicate and better understand human diseases,” he concludes.


The human cognition-enhancing CORD7 mutation increases active zone number and synaptic release. Mila M. Paul et al. Brain, awac011. DOI:https://doi.org/10.1093/brain/awac011

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