Scientists around the world have discovered 29 new genetic variants associated with MS (multiple sclerosis). They say their findings should help researchers develop new treatments that specifically target areas of the patient's immune system. They published their study in the journal Nature.
The study was done by several researchers from around the world and was led by the Universities of Oxford and Cambridge, in England. The authors say this is the largest study yet into genes and MS.
This new discovery means that scientists now have over 57 genetic clues to MS.
Genes only play a part in MS risk. Other factors, such as vitamin D levels and viral exposure are also believed to play a role. We know that the further somebody is from the equator, the higher his/her risk is (vitamin D from sunlight may be a factor).
The authors explained that T-cells and interleukins appear to play a major role in the development of MS. T-cells are a type of white blood cell that set off an immune response. Interleukins are chemicals that stimulate the activities and growth of certain kinds of white blood cells.
Co-author, Alastair Compston, from Cambridge University, said:
"We have implicated genes that are highly relevant to the actions of those drugs. It is now clear that multiple sclerosis is primarily an immunological disease. This is the way to nail this disease and get on top of it."
The researchers examined the DNA of 9,772 individuals with MS and 17,376 people without MS (healthy controls). The patients and the controls came from 15 different countries. In total 23 research groups collaborated. The scientists confirmed the presence of 23 known genetic variations which raise the risk of developing MS slightly, and identified 29 new ones.
They found another 5 genetic variations which are likely to be involved in MS risk - making it a total of 57 genetic variations linked to MS.
Compston said that in 1970 scientists had identified one gene linked to MS, in 2007 the number rose to 3, and during the last three to four years they rose to 20, then 29 and now 57.
In an interview with the BBC, Compston said:
"This is suddenly a big new number of genes to try to understand. 80% of the genes that are implicated by the 57 'hits' are immunological. This shouts out that this is an immunological disease at the beginning. This is a very important confirmation."
Multiple sclerosis is the result of a breakdown of the myelin sheath - a protective coating around the nerve fibers in the spinal cord and brain. As the coating wears away the brain finds it harder to communicate properly with the rest of the body. The patient's ability to walk, feel, control bladder and bowel movements, and even think properly can be affected.
Severity of symptoms varies widely, from mild, where the limbs experience numbness, to very severe, in such cases the patient may be paralyzed, lose vision or have balance problems.
Another study published this week in PLoS Genetics found that some of the genes linked to MS are also associated with other autoimmune disorders, such as Diabetes Type 1 and Crohn's disease.
Approximately 400,000 American have multiple sclerosis, says the National Multiple Sclerosis Society.
Written by Christian Nordqvist