Genetic researchers reporting in the journal Nature Genetics have discovered an additional 48 genetic variants influencing the risk of developing multiple sclerosis. The study nearly doubles the number of known genetic risk factors and thereby provides additional insights into the biology of this debilitating neurological condition.

Multiple sclerosis is a chronic disabling neurological condition that affects over 2.5 million individuals worldwide.

The disease results in patchy inflammation and damage to the central nervous system that causes problems with mobility, balance, sensation and cognition depending on the location of the changes. Neurological symptoms are often intermittent in the early stages of the disease but tend to become persistent and progressively worsen with the passage of time for the majority of patients.

The risk of developing multiple sclerosis is increased in those who have a family history of the disease.

Research studies in twins and adopted individuals have shown that this increased risk is primarily the result of genetic risk factors.

The new study takes advantage of custom designed technology known as ImmunoChip – a high-throughput genotyping array specifically designed to interrogate a targeted set of genetic variants linked to one or more autoimmune diseases.

The researchers used the ImmunoChip platform to analyze the DNA from 29,300 individuals with multiple sclerosis and 50,794 unrelated healthy controls, making this the largest genetics study ever performed for multiple sclerosis.

In addition to identifying 48 new susceptibility variants, the study also confirmed and further refined a similar number of previously identified genetic associations.

With these new findings, there are now 110 genetic variants associated with multiple sclerosis.

Although each of these variants individually confers only a very small risk of developing multiple sclerosis, collectively they explain approximately 20 per cent of the genetic component of the disease.

“With the release of these new data, our on-going effort to elucidate the genetic components of this complex disease has taken a major step forward. Describing the genetic underpinnings of any complex disease is a complicated but critical step. By further refining the genetic landscape of multiple sclerosis and identifying novel genetic associations, we are closer to being able to identify the cellular and molecular processes responsible for MS and therefore the specific biological targets for future drug treatment strategies,” said lead author Dr Jacob McCauley from the University of Miami.

“These results are the culmination of a thoroughly collaborative effort. A study of this size and impact is only possible because of the willingness of so many hard working researchers and thousands of patients to invest their time and energy in a shared goal.”

“This is another excellent example of the power of international collaboration. Each of the new associations brings nearer an understanding of how multiple sclerosis develops and thereby closer to our ultimate goal of a rational therapy that is both safe and effective at all stages of the disease,” said co-author Prof Stephen Sawcer from the University of Cambridge, UK.

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Bibliographic information: McCauley et al. Analysis of immune-related loci identifies 48 new susceptibility variants for multiple sclerosis. Nature Genetics, published online September 29, 2013; doi: 10.1038/ng.2770