Genetics and pain

It has been well known for years that there is considerable interindividual variability in the sensitivity to and tolerance of experimental pain stimuli, in the propensity to develop painful pathologies, and in the response to analgesic therapies; however, this does not mean that such differences are because of genetic factors alone, as pain is a complex phonemenon in which psychological and environmental factors, for example, as well as those inherent to physiological mechanisms, play an important role. Several different methods are used in genetic pain research. Although the identification of mutations can explain some very infrequent pathologies that follow Mendelian patterns of inheritance, the research method used in most cases is the genetic association study, which tests the correlation between a certain phenoytpe (pain) and a polymorphism or single-nucleotide polymorphism. At present there is evidence suggesting that genetic factors may be at least partially responsible for the greater pain experienced by certain individuals following an acute injury, such as a surgical intervention; however, studies analyzing the influence of genetics on chronic postsurgical pain have been scarce.