Study Finds OA Highly Heritable Compared with Other Rheumatic Diseases
Background & Objectives: Musculoskeletal pain conditions are among the most common causes of disability worldwide, with osteoarthritis (OA) being the most prevalent. The genetic contribution to OA, especially in the hip, has been reported to be high, but OA’s heritability (i.e., the total genetic contribution to a trait) compared with other common rheumatic diseases is largely unknown.
Previous studies of the heritability of musculoskeletal disease tend to report heritabilities between ~20% and 80%. The largely varying estimates across different cohorts with different settings and inclusion criteria make the interpretation of the findings challenging because no direct comparison between diseases is possible.
Magnusson et al. sought to compare how much genetics contributes to osteoarthritis with the genetic contribution to other rheumatic/musculoskeletal diseases (RMDs) in the same population, and to explore the role of any shared genetics between OA and other rheumatic/musculoskeletal diseases.
Methods
The researchers used data from the Swedish Twin Registry, a national twin registry containing data on all Swedish twins born between 1911 and 1980, as well as the Swedish National Patient Register. The researchers estimated the heritability of OA in 59,970 twins aged 35 years or older, and compared it with other musculoskeletal pain conditions, including back and neck pain, shoulder pain, rheumatoid arthritis (RA), spondylarthritis including psoriatic arthritis (SpA/PSA), myalgia and osteoporosis.
The twins were followed until 2017 (i.e., for up to 20 years). Family-based studies are useful in disentangling the relative contribution of genetic and environmental factors to a disease because they allow for the estimation of heritability or to a combination of traits. The researchers estimated how much covariance between OA and each of the other rheumatic conditions could be explained by genetics by studying phenotypic correlations in classical, bivariate twin models.
Results
Any-site OA and hip OA (50% and 64%, respectively) were among the most heritable RMDs compared with fibromyalgia—the lowest at 23%—and spondylarthritis, the highest at 63%. The highest phenotypic correlations were between OA (any joint site) and shoulder pain in the same individual, of which 70% could be explained by shared genetics.
Conclusion
OA has relatively large heritability compared with other RMDs. The co- existence of OA and shoulder pain, as well as back pain, was common and could often be explained by genetic factors.
For complete details, including source material, refer to the full study.
