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Researchers find evidence of multigenetic etiology for degenerative disc disease
They studied more than 120 SNPs from 28 candidate genes as potential risk factors.
BERGEN, Norway — Finding genetic causes for various diseases has generated hope for new treatments and cures. Recently a team of international researchers identified new genes likely responsible for intervertebral disc degeneration.
During a multicenter study, extensive analysis showed 24 genes were positively associated with specific signs of disc degeneration and changes on MRI, according to Tapio Videman, MD, at the University of Alberta, Edmonton, Alberta.
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Image: Videman T |
“The findings support a multigenetic origin for disc degeneration,” he said, describing the research as challenging and “still a work in progress.”
Signal intensity was the most significant MRI finding that correlated with genes, Videman told Orthopedics Today.
He presented results at the International Society for the Study of the Lumbar Spine 33rd Annual Meeting, here.
Classic twin studies previously showed that genes had a dominant effect on disc degeneration. But the amount of that effect, including the extent of the genetic variance and exact roles the different genes played, was unclear from that work, Videman told Orthopedics Today.
But it was a start.
For this study, nearly a dozen researchers from Canada, Finland and the United States analyzed genetic factors and MRIs for a population sampling of more than 600 Finns. They performed in-depth analysis of 28 candidate genes for degenerative intervertebral discs, selected by world-renowned geneticist Leena Peltonen, MD, PhD, University of Helsinki, who is one of the investigators.
First, researchers developed special digital measurements to assess the different findings considered important in the spine as seen on 1.5-Tesla MRIs, including measurements for reactionary and mechanical findings, like general wear and tear.
Investigators then attempted to correlate phenotypes consisting of six degenerative lumbar spine changes seen on MRI with more than 120 single nucleotide polymorphisms, or SNPs, from the 28 candidate genes. They made adjustments for age, occupational loading and total body weight/axial disc area (P<.05), three factors previously associated with degenerative findings.
Signal variance uncovered
They found 24 of 28 candidate genes associated with at least one phenotype, which explained 0.7% to 4.0% of the variances they saw in MRI signals. For example, they found about a dozen genes, including aggrecan, four to seven collagen genes, one matrix metalloproteinase gene, and one to three interleukin genes, associated with disc narrowing and bulging assessed quantitatively and qualitatively, with quantitative bulging, and with adjusted disc signal.
“Disc signal was associated with 14 genes and in SNPs of eight candidate genes,” Videman said.
The team also found an interleukin gene and seven collagen genes associated with annular tears analyzed quantitatively.
Other associations found included a connection between herniations and collagen and interleukin genes, and between Schmorl’s nodes and 12 genes, including the aggrecan gene, and collagen and interleukin genes.
“I think it has been quite obvious that there’s a dominant hereditary component to disc degeneration.”
For more information:
- Videman T, Saarela J, Kaprio J, et al. Most of the 28 studied candidate genes were associated with the degenerative MRI findings in the intervertebral disc. #21. Presented at the International Society for the Study of the Lumbar Spine 33rd Annual Meeting. June 14-17, 2006. Bergen, Norway.