Twin Study Shows that Disc Degeneration May be Genetic
BY LAUREN UZDIENSKI, JUNE 10, 2008
Results from the Finnish Twin Spine Study show that disc degeneration may not be the result of physical strain, but genetically determined. The study, which was initiated in 1991, examined 147 pairs of identical and 153 pairs of fraternal male twins; this analysis considered pairs of identical male twins where one twin had a sedentary job and the other had a job that was physically demanding. When spinal x-rays were compared, there was surprisingly little difference in the twins' levels of spinal degeneration.
Despite one twin's increased exposure to suspected risk factors for back pain and spinal disorders, a side-by-side comparison of x-rays for both twins showed similar degrees of degeneration for both twins, as well as the same types of disease and spinal levels affected. In suggesting that susceptibility to spinal disease is genetically determined, the data counters the commonly accepted injury model, which asserts that activity and strain are the primary influence on spinal disease and progression. While there was an impact from physical loading, including handling heavy loads, bending, twisting and static work in awkward postures, it appeared minimal in the context of this study.
Data from this study could develop into an intriguing hypothesis for gene therapy. Teams of researchers North America and Europe are currently conducting further research into specific genes and biological mechanisms at work in disc degeneration and back pain; understanding how degeneration progresses over time; and differentiating normal, inconsequential changes from degenerative changes that lead to pain.
