Tuesday, August 16, 2011
Multiple sclerosis genes identified,chance of a cure?
Multiple sclerosis genes identified in largest-ever study of the disease
Most of the newly discovered multiple sclerosis (MS) gene variants are involved in the body's immune system
Alok Jha, science correspondent
guardian.co.uk, Wednesday 10 August 2011 19.00 BST
Computer-generated image of the DNA double helix
Computer-generated image of the DNA double helix. The study compared DNA from 9,772 people with MS with that from 17,376 healthy people. Photograph: Rex Features
Scientists have discovered 29 new gene variants that are implicated in multiple sclerosis, following the largest ever study of the genetics of the disease.
The genes are involved in controlling parts of the body's immune system, confirming research strategies and pointing to possible treatments for people who develop MS. The discoveries more than double the list of parts of the human genome that researchers believe contribute to the disease.
MS is one of the most common diseases of the nervous system, affecting more than 2.5 million people around the world. It is caused by damage to the protective insulation around nerve fibres, called the myelin sheath, preventing the nerves from working properly. This can affect everyday activities including sight, walking, thinking and control of organs.
In the latest study, led by Alastair Compston from the University of Cambridge, scientists looked at 600,000 locations in the DNA from 9,772 people with MS and compared it with those of 17,376 unrelated healthy people.
It is the largest-ever study into the disease, involving 250 researchers in the International Multiple Sclerosis Genetics Consortium and the Wellcome Trust Case Control Consortium. The results were published on Wednesday in Nature.
The first gene to be linked to MS, called HLA, was found in the early 1970s. Since then, several more genes have been implicated. In the Nature paper, researchers confirmed the involvement of 23 previously suspected gene variants and found 29 new variants. A further five variants were identified as strong candidates for future studies of the disease.
"The genes implicated by these 57 regions tell a very coherent story," said Compston. "There is a narrative that goes across these which is extremely informative – the story is immunological – 80% of the genes within the regions implicated are intimately involved in the workings of the immune response. This puts immunology right at the front end of the disease, unambiguously."
Many of the genes identified by Compston's team are involved in the function of T-cells, a type of immune cell that is responsible for destroying foreign invaders. Of the new gene variants found for MS, around a third have already been linked to a range of autoimmune conditions, where the T-cells malfunction and start attacking the body's own cells, such as Crohn's disease and Type 1 diabetes.
The findings also confirm some of the research scientists had already been pursuing. Four of the gene variants for MS are directly associated with drugs that are either already licensed or in clinical trials.
Peter Donnelly, a co-author of the research and head of the Wellcome Trust Centre for Human Genetics at Oxford University, said the study still did not reveal the complete picture for MS. "Our best guess at this is that, collectively, now the variants explain about 20% of the heritability," he said. "The rest will be down to a multitude of as-yet-undiscovered gene variants, each adding a tiny percentage to the overall risk of developing the disease."
Simon Gillespie, chief executive of the MS Society said: "By identifying which genes may trigger the development of MS, we can identify potential 'risk factors' and look at new ways of treating, or even preventing, the condition in the future. The MS Society is delighted to have helped fund this groundbreaking research."
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