High rates of Multiple Sclerosis in Orkney remain a mystery
New research using Orkney Complex Disease Study (ORCADES) and Viking Health Study - Shetland data shows that common genetic variants do not explain high numbers of Multiple Sclerosis (MS) cases in Orkney.
Cases of MS are higher in Orkney than anywhere else in the world. Many researchers have tried to understand why MS rates are so high in Orkney and have been unable to find a reason.
In the past, researchers used ORCADES data to try and understand the role that vitamin D played in MS rates. They found that low levels of vitamin D do play an important role in influencing someone's risk of getting MS. However, the levels of Vitamin D in Orkney are not different enough from elsewhere in Scotland to explain why MS cases are are so much higher in Orkney. In fact, levels of vitamin D in Orkney were actually higher than in Glasgow! To read more about that study, click the link below.
ORCADES study finds holidays in the sun hold key to boosting vitamin D
In the latest research, led by Professor Jim Flett Wilson, the mystery has continued. Researchers aimed to understand if common genetic variants played a role in the high number of MS cases in Orkney. To do this, they used as a 'polygenic risk score' to help understand how a person's risk of MS compares to others with different genetics.
Sadly, the results for this study were similar to the results found in the previous vitamin D work. A genetic variant in the region known as the 'Human Leukocyte Antigen' (HLA) is a little more common in Orkney than in other areas of Scotland. However it's not common enough to explain why there is such a big difference. Despite that, Professor Wilson believes that's not the end of the story.
It's not that we are looking for one thing. It will be a combination. If someone has a rare variant increasing their risk of MS, and also has low vitamin D, maybe smokes, maybe has the HLA variant as well, then the combination of risk factors might be enough to tip them into clinical disease.
In the future, Professor Wilson hopes to look at the combination of factors that might be making MS rates higher in Orkney, compared to elsewhere. He particularly wants to look in more detail at rare genetic variants.
Our data may not have helped discover why there is such a big difference in MS case numbers yet. However, each possibility that is removed means we can narrow down our efforts to understanding currently untested factors that might be influencing it.
This research was funded by the MRC Human Genetics Unit and the Shetland and Orkney Multiple Sclerosis Research Project. If you'd like to read the full paper, click the link below.
Contribution of common risk variants to multiple sclerosis in Orkney and Shetland