Genes increase a person's sensitivity to pain
Researchers have identified three variants of a single gene that are responsible for increased sensitivity to mechanical pain.An international team of researchers has shown that the presence of one of the three variants of the SCN9A gene inherited from Neanderthals lowers the pain threshold - increases a person's sensitivity to mechanical influences. The variations are most common in Native American populations.
The SCN9A gene encodes a protein that delivers sodium to cells and helps send signals to nerves that recognize pain. In a study published in 2020, another group of scientists found a correlation between variations in this gene and pain sensitivity in Europeans.
In the new paper, the researchers confirmed the previous finding with data from Hispanics. They also showed that the prevalence of gene variants associated with pain sensitivity was higher in Native Americans.
In the first part of the study, researchers analyzed genetic samples collected from more than 5,900 people living in Brazil, Chile, Colombia, Mexico, Peru and Chile. On average, 46% of participants had Amerindian ancestry, 49.6% had European ancestry and 4.4% had African ancestry.
Analysis revealed 30% of participants had the D1908G gene variant, and another 13% of participants had two other gene variants, V991L and M932L, which are typically inherited together. And the prevalence of these variations increased among Peruvians, who had the highest proportion of Amerindian ancestry. In contrast, the prevalence of these variations decreased among Brazilians with predominantly European ancestry.
After the genetic analysis, the researchers conducted pain threshold tests on more than 1,600 volunteers in Colombia. The scientists used pressure, heat and cold sensitivity tests and asked volunteers to report as soon as they felt discomfort. The analysis confirmed that hypersensitivity correlated with the presence of one of three variants of the SCN9A gene.
Scientists believe that the presence of genetic variations created an evolutionary advantage for Neanderthals and the first members of modern humans to reach the Americas. "People who first reached North America would have had to endure harsh and cold conditions, so it's possible that these variants have other effects besides pain - for example, they could have helped people cope with the cold in some way," says Pierre Faux, co-author of the study.