Pain reporting at different body sites is explained by a single underlying genetic factor

OBJECTIVES: Musculoskeletal pain is reported commonly; however, the extent to which pain in individual body areas reflects the severity of site-specific pathology or a more generalized propensity to feel pain is uncertain. We used a classical twin design to examine the pattern of pain reporting at different body sites among monozygotic (MZ) and dizygotic (DZ) twins to assess its heritability and to examine evidence for a common underlying propensity to report musculoskeletal pain. METHODS: A well-characterized sample of female twins (TwinsUK cohort) was sent a questionnaire to determine their experience of pain in the neck and back, elbow, knee, thigh, hands or feet. The genetic contribution to pain reporting was assessed through univariate and multivariate analyses. RESULTS: Pain was reported with a prevalence of 17-46%, depending on the anatomical site. Univariate analysis indicated an underlying heritability for pain reporting at all sites of 28-71%. Pain reporting at different sites was modestly but uniformly correlated; a single factor accounted for 95% of the overall variance in pain reporting. The correlation for scores on this factor was 0.46 in MZ twins and 0.23 in DZ twins, corresponding to a 'pain reporting factor' heritability of 46% (95% CI 40%, 52%). CONCLUSIONS: A single genetic factor underlies the propensity to report body pain at different musculoskeletal sites. These findings, which contrast with those for radiographic OA that is determined by genetic factors specific to each anatomical site, will inform the future search for therapeutic targets to treat pain in chronic degenerative diseases.