Researchers have identified the first genetic marker of multiple sclerosis severity. The genetic variant was seen in people who experienced quicker progression of the disease, resulting in greater disability. The finding could lead to more effective treatments for the condition.
Multiple sclerosis is a chronic neurodegenerative disease that causes brain lesions and leads to difficulties with walking, memory and other bodily functions. It is 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 his colleagues performed a genome-wide association study using data from 22,389 people with multiple sclerosis. These types of studies use statistical analysis to pinpoint genes associated with certain characteristics, such as multiple sclerosis severity.
After analysing almost 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. On average, people with the marker required walking assistance 3.7 years earlier than those without it.
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 the number of lesions in the outer layer of their brain and in their brainstem than those without it. The researchers say this indicates the variant has a connection to the neurological injuries that trigger the progression of multiple sclerosis.
The finding could help clinicians identify which people with multiple sclerosis are more likely to have severe disease and adjust treatment plans accordingly, says Violaine Harris at the Tisch MS Research Center of New York. “This new data could also help us understand and maybe even stratify patients when we’re testing new treatment approaches,” she says.
One limitation of the research is that all the participants were of European ancestry. The researchers were unable to replicate the findings in two cohorts of people from African and Hispanic ancestry. They say this may be due to the small sample size of these cohorts.