Researchers may have identified key genes linked to why some people have a higher tolerance for pain than others.

Study author Tobore Onojjighofia, MD, MPH, with Proove Biosciences and a member of the American Academy of Neurology and colleagues evaluated 2,721 people diagnosed with chronic pain for certain genes. Participants were taking prescription opioid pain medications. The genes involved were COMT, DRD2, DRD1 and OPRK1. The participants also rated their perception of pain on a scale from zero to 10. People who rated their pain as zero were not included in the study.

Low pain perception was defined as a score of one, two or three; moderate pain perception was a score of four, five or six; and high pain perception was a score of seven, eight, nine or 10.

Nine percent of the participants had low pain perception, 46 percent had moderate pain perception and 45 percent had high pain perception.

The researchers found that the DRD1 gene variant was 33 percent more prevalent in the low pain group than in the high pain group. Among people with a moderate pain perception, the COMTand OPRK variants were 25 percent and 19 percent more often found than in those with a high pain perception.

The DRD2 variant was 25 percent more common among those with a high pain perception compared to people with moderate pain.