Pain research update from a genetic point of view.

Molecular biology investigates the genetic causes of many diseases. Currently, molecular biology in pain research lags behind the investigations of the molecular basis of mental disorders. A significant challenge in pain genetic research is the fact that pain involves emotional factors. Tools available for pain measurements and interindividual comparisons have been imperfect. Another problem relates to research ethics. Unlike animal studies, there is very limited ability to evoke experimental pain in a group of humans with precisely defined age, sex, medication, and pain experience. Nevertheless, pain investigations at the gene level have commenced. Recent progress in molecular biology has enabled gene expression modulation in animal models using "knockout," "oligo-antisense," and viral vector techniques. These methods enable investigation, at molecular level, as to which of the approximately 30,000 genes of the human genome might be involved in pain mediation, which of these are polymorphic, and which polymorphisms are responsible for interindividual differences in pain perception. Recently, the genetic bases of familial hemiplegic migraine and congenital insensitivity to pain with anhidrosis have been shown. In the last 6 years, genetic pain research has focused on potential gene therapy for patients with chronic pain. Results of these studies are encouraging and potentially applicable to clinical practice in the near future.