Scientists have taken a step towards understanding why Northern Ireland has one of the highest rates of multiple sclerosis in the world after finding a strong link between the debilitating condition and low levels of sunshine.
The MS Society has released the results of new research which found significant evidence that a direct interaction between vitamin D, produced in the body through sunlight, and a common genetic variant raises the risk of developing MS.
The research, published today in the journal PLoS Genetics, suggests that a vitamin D deficiency during pregnancy and the early years may increase the risk of the baby going on to develop MS later in life.
The causes of MS are unclear, but it has been known for some time that a combination of environmental and genetic factors play a role.
This research may now have narrowed the search for environmental risk factors down to the role of vitamin D.
Previous studies have shown that populations from northern Europe have an increased risk of getting MS if they live in areas receiving less sunshine.
MS is more common in areas further away from the equator.
It is virtually unheard of in places like Malaysia or Ecuador, but is relatively common in Britain, the US, Canada and Scandinavia.
Scotland has the highest prevalence in the world, with around 10,000 people living with MS. Northern Ireland has the second highest prevalence in the world with 4,000 sufferers.
Through the study — funded by the UK’s MS Society, the MS Society of Canada, the Wellcome Trust and the Medical Research Council — researchers at the University of Oxford and the University of British Columbia have established a direct relationship between a gene variant known as DRB1*1501 and vitamin D.
Proteins activated by vitamin D in the body bind to a particular DNA sequence lying next to the DRB1*1501 variant, in effect switching the gene on.
Patricia Gordon, director of the MS Society Northern Ireland, said the “remarkable results” would go some way to understanding why Northern Ireland has such high levels of the condition.
“These remarkable results tie together leading theories about the environment, genes and MS. Northern Ireland has the second highest levels of multiple sclerosis worldwide with over 4,000 people affected, making these research developments even more significant,” she said. “This is one part of the overall jigsaw.”
A common but incurable disorder
MS is the most common disabling neurological disorder affecting young adults. More than 85,000 people in the UK have MS, 4,000 of them in Northern Ireland.
- The condition is caused by damage to myelin, the protective sheath surrounding nerve fibres of the central nervous system. This damage means messages between the brain and the body are not transmitted as they should be, leading to a range of symptoms including loss of sight and mobility, muscle spasms, slurred speech, pain, fatigue and depression.
- There is no cure for MS and few effective treatments.
- Three times as many women as men are affected and the average age of diagnosis is in the early thirties.