New genetic clues to multiple sclerosis
Discovery of new genetic risk factors for multiple sclerosis confirms that the disease is of immunological origin
12th August - In a large international study into multiple sclerosis (MS), scientists have discovered new genetic variations that are implicated in the disease. Most of the genes are linked to the body's immune system, confirming existing theories that MS is immunological in origin.
Inflammation comes first
The results will help settle the debate over the complex sequence of events that leads to disability in multiple sclerosis. This will have important implications for future treatment strategies, according to Professor Alastair Compston of the University of Cambridge, who co-led the study. It has previously been suggested that MS is a degenerative disease that triggers immune system inflammation, but the new findings indicate that the inflammation comes first, according to Professor Compston.
MS is not directly inherited and it is not caused by any single gene. The results of the study, published in Nature on 10th August, bring the number of genes linked to MS to 57. The new research confirms 23 genes suspected to be linked to the disease and adds another 34. Of those 34 genes, 29 are definite and five are probable.
MS, which affects around 100,000 people in the UK, is the most common neurological condition in young adults. It is an autoimmune disorder, which means that the body attacks its own cells. MS affects the central nervous system (the brain and spinal cord). Each nerve fibre in the central nervous system is surrounded by a substance called myelin, which helps messages from the brain travel to the rest of the body. In MS, the immune system mistakes the myelin for a foreign substance and attacks it. This disrupts the transfer of messages from the brain. People with the disease may have problems with vision, mobility and balance, and may suffer from muscle weakness.
The genes identified in the new research include those that influence specific cells of the immune system, either through controlling interleukins (messenger chemicals that help immune cells communicate) or T-cells, which help the body fight off intruders. About a third of the genes identified are also linked to other autoimmune diseases, such as Crohn's disease, rheumatoid arthritis and type 1 diabetes.
The study was carried out by an international team of researchers, led by the University of Oxford and the University of Cambridge. It involved 9,772 people with MS and a comparison group of 17,376 people who did not have the disease, from 15 countries in all.
Treatments should target immune system
For MS patients, the results suggest that treatments not targeted towards the immunological system do not make sense, according to Professor Compston. The findings will help confirm the direction of existing research into MS. Four of the gene variants are already targeted by medicines approved to treat the disease or in clinical trials.
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."
Experts also believe that environmental factors, such as an infection or low levels of vitamin D, may play a role in multiple sclerosis.