Illustration of nerve cells damaged by multiple sclerosis
Science Photo Library/Alamy
Researchers have identified the first genetic marker of multiple sclerosis severity. The genetic variant was seen in people who experienced faster disease progression, resulting in greater disability. The finding may lead to more effective treatments for the condition.
Multiple sclerosis is a chronic neurodegenerative disease that causes brain damage and leads to problems with walking, memory and other bodily functions. It’s unclear why some people with the condition can live relatively normal lives with treatment, while others experience rapid disease progression.
So, Adil Harroud at McGill University in Canada and colleagues conducted a genome-wide association study using data from 22,389 people with multiple sclerosis. These types of studies use statistical analysis to locate genes associated with certain traits, such as the severity of multiple sclerosis.
After analyzing nearly 8 million genetic variants, the researchers found one with a significant association with a score that measures disability in people with multiple sclerosis, adjusted for age. People with a marker needed walking assistance an average of 3.7 years earlier than those without.
The team then examined brain tissue samples collected from a separate group of 290 people with multiple sclerosis who had died. On average, those with the marker had nearly twice as many lesions in the outer layer of their brain and in their brain stem than those without it. The researchers say this indicates that the variant is linked to the neurological injuries that drive the progression of multiple sclerosis.
The finding could help clinicians identify which people with multiple sclerosis are more likely to have serious disease and adjust treatment plans accordingly, says Viola Harris at the Tisch MS Research Center in New York. “This new data could also help us understand and maybe even stratify patients as we test new treatment approaches,” she says.
A limitation of the study is that all participants were of European descent. The researchers were unable to replicate the findings in two cohorts of people of African and Hispanic descent. They say this may be due to the small sample size of these cohorts.
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