A new study published online first in the journal Annals of Rheumatic Diseases on 19 September, shows how for the first time researchers have identified a gene linked to a common cause of lower back pain: a condition known as lumbar disc degeneration (LDD).
While more research is needed to fully understand the link, the team, from King’s College London, hopes the study will lead to new treatments for the condition.
LDD is a common age-related problem: for instance, over a third of women aged 30 to 50 will have at least one degenerate disc in their spine.
When the disc degenerates it becomes dehydrated, loses height, and the vertebrae on either side develop bony growths called osteophytes. As these changes take place, they cause or exacerbate lower back pain.
Back pain is not a well understood condition, despite the fact it “can have a serious impact on people’s lives and is one of the most common causes of sickness leave, costing both the NHS and UK economy billions each year,” first author, Frances Williams, Senior Lecturer in the Department of Twin Research and Genetic Epidemiology at King’s College London, says in a press statement.
In the case of LDD, scientists have for some time believed genes are involved, because up to 4 out of 5 people with LDD inherit the condition.
Williams and colleagues are the first to suggest there is a link between LDD and a gene called PARK2.
For their study, the researchers examined spinal MRI scans of 4,600 people whose genes had been mapped using genome-wide association (GWA) techniques.
They analyzed the MRI scans using a measuring technique they had developed, which they describe in their paper as “a continuous trait based on disc space narrowing and osteophytes growth which is measurable on all forms of imaging (plain radiograph, CT scan and MRI)”.
The participant data came from “five cohorts of Northern European extraction each having GWA data imputed to HapMap V.2”.
Using meta-analysis techniques (a statistical method that allows data from studies of similar design to be pooled and analyzed as if they came from one large study), the researchers compared the MRI measures with the genome data, and found a strong link between a variant of PARK2 and the presence of degenerate discs.
This led them to suggest the gene affects the rate at which the discs degenerate.
“We have performed, using data collected from around the world, the biggest genome-wide association analysis of lumbar disc degeneration (LDD),” says Williams.
“We have identified a gene called PARK2 as associated with LDD. We have shown that the gene may be switched off in people with the condition,” she adds.
Although they don’t know exactly how this happens, the researchers suggest environmental factors are involved, for instance lifestyle and diet. These factors could trigger epigenetic changes that in turn switch off the gene.
The team hopes disc researchers will now take the findings further, and discover exactly what role PARK2 plays:
“It is feasible that if we can build on this finding and improve our knowledge of the condition, we may one day be able to develop new, more effective treatments for back pain caused by this common condition,” says Williams.
Funds from the Wellcome Trust and Arthritis Research UK paid for the study.
Written by Catharine Paddock PhD