An elderly woman from Italy, her two daughters and three grandchildren, do not feel pain due to a mutation in the ZFHX2 gene, which is responsible for assembling most of the pain receptor components in nerve cells, according to an article published in the journal Brain.
“If members of this family break their arms or legs, they initially feel a little pain, but it goes away quickly. For example, Laetitia broke her shoulder while skiing, did not notice it and continued to ski all day. She only found out about the fracture the next day,”said James Cox from University College London (UK).
In the genome of humans and other animals with a branched nervous system, there are several dozen genes that are responsible for interacting with the environment and generating danger signals. The most effective and universal of these signals is the feeling of pain, which helps people remember dangerous objects and phenomena and avoid them in the future.
Accordingly, if such genes are broken, then their owner either ceases to feel pain at all, or only feels some. A striking example is the Cape hairless mole rat, small rodents that are almost unresponsive to acids, fire and many other stimuli due to mutations in genes responsible for transmitting pain signals to the brain.
Cox and his colleagues have uncovered the genetic secrets of a unique Italian family - a 78-year-old grandmother, her 50-year-old daughters and teenage grandchildren - who rival diggers for pain insensitivity.
For the first time, scientists learned about the family of "supermen" in 2008, when Italian doctors told about it. Its members often received fractures or severe bruises and cuts and did not notice this, continuing to act with their arms and legs, as if they were not broken.
For a long time, doctors could not understand how this happened - these people did not feel the most serious pain associated with damage to bones and muscles, but at the same time they often complained of headaches and pain in the intestines, as well as discomfort during childbirth. To clarify the issue, scientists decoded the DNA of family members and studied the structure of all genes associated with pain.
As it turned out, the reason for the development of "superpowers" was a single mutation in the ZFHX2 gene, which plays the role of a kind of regulator of the sensitivity of nerve cells in response to various pain stimuli.
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Interested in the role of this gene in the work of the "pain center" in the brain, scientists first completely removed it from the DNA of mice, and then transplanted them with a "mutant" version of ZFHX2. As a result, the rodents almost completely stopped responding to heat, burns, burning substances and other painful stimuli, because the work of 16 other genes, the activity of which is controlled by ZFHX2, changed.
This discovery, Cox notes, could help scientists create drugs that would suppress it and temporarily "turn off" pain. As for the Italian family, the scientists suggested that its members go through the reverse procedure and return the feeling of pain, but they refused.