The first genetic advance in multiple sclerosis research in three decades has opened new approaches to treating the neurological disorder, scientists said yesterday.

Research has identified two genetic variants that each raises a person’s risk of developing MS by about 30 per cent, shedding new light on the origins of the autoimmune disease that could ultimately lead to better therapies.

The two genes are the first to be linked conclusively to MS since the mid-1970s, when the only other gene that is known to contribute to the condition was found.

Their discovery is particularly promising as both are involved in managing the activity of T-cells, the “infantry” of the immune system that sometimes mistakenly attack healthy tissue to cause autoimmune conditions. In MS, the immune system starts to destroy the fatty myelin sheaths that insulate nerve cells, leading to progressive neurological damage.

Both genes, which control receptors that T-cells use to find their targets, are potential targets for new drugs to control MS. They were found in a major study of the genetics of MS published in the New England Journal of Medicine, and the significance of one has been confirmed in two separate papers published in Nature Genetics.

Scientists said that the genes would have important implications for understanding the disease and ultimately for treating it.

Margaret Pericak-Vance of the University of Miami, a senior member of both research groups, said: “They give us a new way of looking at the biology of the disease, and could be targets for therapeutic development."

Stephen Hauser, Professor of Neurology at the University of California, San Francisco, said of one of the genes, the interleukin-7 receptor (IL-7R): “I believe that this receptor and its interaction with regulatory T-cells will now become a major focus of research on MS.”

While MS is not directly inherited or caused by a single gene, it is known to be partly inheritable: people with close relatives who have the condition are at higher risk. Since the 1970s, however, only one gene that contributes to a raised risk has been identfied. A variant of this gene, known as HLA-DRB1, seems to make the body worse at recognising its own tissue, and increases an individual’s chances of developing MS by up to four times.

The new genetic variants affect a different part of the immune system, the control receptors on T-cells that act as receiving antennae for interleukins – proteins that summon these killer cells to attack invaders.

Each has less effect on MS than HLA-DRB1, raising the risk by about 30 per cent, but both are common.

Some 72 per cent of white Europeans have the most damaging version of the interleukin-2 receptor (IL-2R) gene, while 56 per cent have the most damaging variant of the IL-7R gene.

This indicates that these genes are far from the only contributors to MS – the overwhelming majority of people who carry the risky variants are healthy. Many other genes, as well as environmental factors, are involved.

David Hafler, Professor of Neurology at Harvard Medical School in Boston, who led one of the research teams, said: “Each gene contributes only a small amount of risk. The big question is, how do they interact with each other, and are they in common pathways? A major effort to understand the full complement of genes involved in MS will be necessary to completely understand the disease.” A fuller knowledge of how the genes raise risk, however, will still be useful in designing new drugs. It may even prove possible to correct the inter-leukin signalling pathways to stop the condition from developing.

Simon Gregory, of Duke University in North Carolina, who contributed to the research, said: “Our finding is very important because the genetic factors that are already known to be associated with multiple sclerosis only explain less than half of the total genetic basis for the disease.”

The discovery that IL-2R is linked to MS is also significant because previous research has suggested it also contributes to two other autoimmune conditions, type 1 diabetes and autoimmune thyroid disease.

“Scientists are increasingly finding genetic links between autoimmune diseases that affect different tissues in the body, including type 1 diabetes and rheumatoid arthritis,” Professor Hafler said. “This study will likely spur further research into the connection between these seemingly separate conditions.”

The findings have emerged from two slightly different approaches to gene-hunting that have become possible because of advancing technology and the mapping of the human genome. The most important was a genome-wide association study, which scanned more than 500,000 genetic variations from more than 13,000 people to find associations between particular mutations and MS.

“People have been looking for genes involved in MS for 30 years,” Professor Hafler said. “Why weren’t they found? The answer is you couldn’t do it without the sequence of the human genome.”

Lee Dunster, of the MS Society, said: “One of the great unknowns about MS is what causes it and this looks like a welcome breakthrough in getting to grips with the genetics behind the disease. People with MS often worry about what caused it, and particularly whether it will affect their children, so a better understanding of the role of certain genes is good news. These latest findings will be of great interest to researchers trying to develop future treatments.”

The NHS is considering funding a trial to compare an unlicensed drug which prevents blindness with its expensive, licensed counterpart. British doctors, in a challenge to the prices charged by pharmaceutical companies for Lucentis, are preparing to offer their patients Avastin, its cheaper but unlicensed counterpart which is used widely in the US. Both drugs can save the vision of those who develop an eye degeneration disease but Lucentis costs so much — £761.20 per injection — that it is recommended only in the worst cases.

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