Accordingly, the mutation changes a protein that is active in the retina, but also in the synapses of the brain. The latter ensures that neural signals are transmitted more quickly, thereby increasing intelligence.

Most mutations in our genome have little or no impact. But in some cases, the change in the DNA code disrupts or prevents the production of important proteins and, in extreme cases, triggers fatal diseases. On the other hand, there must also be cases in which mutations bring advantages to their carrier – after all, this is the basis of evolution. However, such positive mutation effects have only rarely been observed to date.

However, Mila Paul from the University of Würzburg and her colleagues have now uncovered an unusual case. The impetus for this came from a specialist article reporting on a newly discovered mutation. This CORD7 mutation exchanges an amino acid in a protein that is active in the retina, but also in the synapses of the brain. In affected patients, this causes a decline in the visual cells and leads to blindness.

But that’s not all: research revealed that people with this inherited mutation scored remarkably well on tests of their verbal intelligence and working memory – they were above average in intelligence. But how could this be explained? Could the CORD7 mutation harm and benefit its carriers at the same time? After all, the affected protein is also needed in the synapses of the brain and thus the switching points of thought.

“Our assumption: The mutation makes the patients so smart because it improves communication between the nerve cells in which the modified protein is integrated,” explains senior author Tobias Langenhan from the University of Leipzig. To investigate this assumption, he and His team examined the mode of action of the CORD7 mutation in more detail.”Of course, you can’t take the measurements on the synapses in the brains of the patients,” says Langenhan.

But there is another way: Conveniently, the RIIM gene affected by the mutation occurs in one of the classic model animals of genetics: the fruit fly Drosophila. “Our research project was designed to insert the patient’s mutation into the corresponding gene in the fly and use methods such as electrophysiology to test what then happens to the synapses,” says Langenhan. The researchers used the proven CRISPR/Cas9 gene scissors to insert the mutation.

The result: “We were actually able to observe that the animals with the mutation showed increased information transmission at the synapses,” the researchers report. Additional analyzes revealed the reason for this. According to this, the active zones on the “sending” part of the synapse move closer together and thus enable an increased release of neurotransmitters. “This causes a faster, more efficient synapse response and increases the amount of neurotransmitter pool available for release,” write Paul and her colleagues.

This could explain how and why the CORD7 mutation also improves thinking skills in humans. “This astonishing effect on the fly synapses is probably also found in the same or a similar way in the patients and could explain the increased cognitive performance, but also their blindness,” says Langenhan. The exchange of just one amino acid in a single protein therefore has a profound negative as well as positive effect.

Source: University of Leipzig

This article was written by Nadja Podbregar

The original of this article “Researchers decode gene mutation that makes you smart – but also blind” comes from scinexx.