Chronic Pain Gene Discovery May Spark Treatments

10 aug 2010- Nearly 20 percent of American adults suffer from persistent, chronic pain, but a new genetic clue may aid in the understanding and treatment of the debilitating condition.

Chronic pain can affect all aspects of life, from sleep, to work, to exercise. Some individuals are more susceptible to pain than others, but the reason for this has not been understood. For example, the amount of pain two patients experience after the same surgery can differ greatly.

An international team of researchers sought to find out if there is a genetic basis for susceptibility to pain. Using animal models, they were able to link mouse chromosome 15 with pain. Using two fine-mapping approaches, they narrowed it down to one gene: Cacgn2, which was previously know to be associated with cerebral function and epilepsy. Before now, no other gene has ever been associated with pain.

To further test the gene, scientists used a mouse strain harboring the mutant gene, previously used for epilepsy research, and the findings were consistent; the mice experienced different behavioral and electrophysiological characteristics linking the chronic pain to Cacgn2.

Researchers wanted to know if the Cacgn2 gene is responsible for chronic pain in humans as well. To find out, they studied a cohort of breast cancer patients that had all or partial removal of the breast, and found genetic polymorphisms in Cacgn2 were significantly associated with chronic pain experienced after surgery.

"The immediate significance is the mere awareness that differences in pain perception may have a genetic predisposition," Ariel Darvasi of the Hebrew University of Jerusalem in Israel, was quoted as saying. "Our discovery may provide insights for treating chronic pain through previously unthought-of mechanisms."

SOURCE: Genome Research, published online August 4, 2010