title: Heritability of low back pain and the role of disc degeneration.
abstract: Twin studies suggest that both disc degeneration and back pain have a genetic component. We were interested in estimating the heritability of low back pain in men and examining whether genetic influences on back pain are mediated through genetic influences on disc degeneration. Thus, we conducted a classic twin study with multivariate quantitative genetic models to estimate the degree to which genetic (or environmental) effects on back pain were correlated with genetic (or environmental) effects on disc degeneration. Subjects included 147 monozygotic and 153 dizygotic male twin pairs (N=600 subjects) from the population-based Finnish Twin Cohort. All subjects underwent lumbar magnetic resonance imaging and completed an extensive interview, including back pain history and exposure to suspected risk factors. Disc height narrowing was the degenerative finding most associated with pain history, and was used to index disc degeneration in the models. Statistically significant genetic correlations were found for disc height narrowing and different definitions of back pain, such as duration of the worst back pain episode (r(g)=0.46) and hospitalization for back problems (r(g)=0.49), as well as disability in the previous year from back pain (r(g)=0.33). The heritability estimates for these back pain variables ranged from 30% to 46%. There also were statistically significant, but weaker, environmental correlations for disc height narrowing with back symptoms over the prior year. A substantial minority of the genetic influences on pain was due to the same genetic influences affecting disc degeneration. This suggests that disc degeneration is one pathway through which genes influence back pain.
authors.affiliation: Faculty of Rehabilitation Medicine, 2-50 Corbett Hall, University of Alberta, Edmonton, Alta., Canada T6G 2G4 National Public Health Institute and University of Helsinki, Helsinki, Finland Department of Orthopaedic Surgery, University of Texas Southwestern, Dallas, USA.
authors.forename: Michele C
authors.initials: MC
authors.lastname: Battié
authors.forename: Tapio
authors.initials: T
authors.lastname: Videman
authors.forename: Esko
authors.initials: E
authors.lastname: Levalahti
authors.forename: Kevin
authors.initials: K
authors.lastname: Gill
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
mesh_terms: D000328:Adult; D000368:Aged; D015897:Comorbidity; D005387:Finland / Q000453:epidemiology; D020022:Genetic Predisposition to Disease / Q000453:epidemiology / Q000235:genetics; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000453:epidemiology* / Q000235:genetics*; D017116:Low Back Pain / Q000453:epidemiology* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014427:Twins / Q000235:genetics*