Low frequency of the disease‐associated DRB1*15‐DQB1*06 haplotype may contribute to the low prevalence of multiple sclerosis in Sami

Harbo, Hanne F.; Utsi, Egil; Lorentzen, Åslaug R.; Kampman, Margitta T.; Celius, Elisabeth Gulowsen; Myhr, Kjell–Morten; Lie, Benedicte A.; Mellgren, Svein Ivar; Thorsby, E.

doi:10.1111/j.1399-0039.2007.00803.x

Cited by 37 publications

(43 citation statements)

References 33 publications

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“…Norway is a relatively homogenous population, except from the aboriginal Sami population in the North, which have a different human leucocyte antigen profile and are proven less prone for autoimmune disorders like multiple sclerosis (MS) and Bechterews [36,37] . Results from genomewide association studies are divergent, both regarding associations within the HLA loci as well as non-HLA alleles across populations [38,39] .…”

Section: Discussionmentioning

confidence: 99%

Geographical Distribution of Myasthenia Gravis in Northern Europe - Results from a Population-Based Study from Two Countries

et al. 2015

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Objectives: To compare the prevalence of myasthenia gravis (MG) subgroups based on immunological markers and clinical presentation in two geographically complete MG populations in northern Europe. Methods: This cross-sectional study included all living MG patients in Norway and a regional cohort from the Netherlands. Patients were identified using their hospital registration codes. Medical charts of subjects >16 years were reviewed. Inclusion criteria were clinical MG, a positive antibody test for acetylcholine receptor (AChR MG) or muscle-specific kinase (MuSK MG), or if seronegative MG, confirmed by an electrophysiological test. Results: 1,205 MG patients (534 Norwegians and 671 Dutch) fulfilled the criteria, giving a higher point prevalence in the Netherlands (167/million, 95% CI 155-180) than in Norway (138/million, 95% CI 126-150). In particular, rates of AChR MG (143 vs. 111/million), MuSK MG (6.5 vs. 0.5/million), and ocular phenotype (62 vs. 24/million) were higher in the Netherlands. Conclusion: Novel findings are an AChR MG geographical north-south gradient and a 2.6-fold more ocular MG patients in the Netherlands than in Norway. The MuSK MG latitudinal gradient supports the notion of a north-south gradient in Europe, with a higher prevalence in the south. The variation is probably explained by genetic differences between the populations, in addition to environmental interactions.

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Section: Discussionmentioning

confidence: 99%

Geographical Distribution of Myasthenia Gravis in Northern Europe - Results from a Population-Based Study from Two Countries

et al. 2015

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“…Also here numbers are small, but recent epidemiological and genetic studies suggest that the lower than expected prevalence of MS above the Arctic Circle could be explained by a traditional diet that is rich in vitamin D [5] and possibly by genetic admixture of the ''MS-resistant'' indigenous Sami [4]. Parallels to this situation could probably be found in Alaska, and population-based ecological and genetic studies in this area would be very interesting.…”

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confidence: 94%

Alaska, multiple sclerosis, and the vitamin D hypothesis

Holmøy

Kampman

2009

J Neurol

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In their recent paper on the relative risk and estimated prevalence of multiple sclerosis (MS) among Alaskan military veterans, Wallin and coworkers found that migration from coterminous US to Alaska decreases MS risk, and that migration in the opposite direction increases it [8]. They conclude that their findings do not support the vitamin D and sunlight ecological hypothesis of MS [1]. We think this is not necessarily correct.The authors identified only one case of MS in men born in Alaska who entered active duty in Alaska, while nine Alaskan born men with residence in another state at entry of active duty developed MS [8]. This increased risk of MS for Alaskan-born moving to the coterminous US is, in our opinion, the main finding of the study, and is indeed consistent with the vitamin D/sunlight hypothesis. As indicated by the month-of-birth effect on MS risk [9], environmental risk factors operate also very early in life, perhaps before birth. In line with this notion, the authors even cite a study that documents poor vitamin D levels in Alaskan children.The authors compare Alaska with Scandinavia, ignoring the exception to the general latitude gradient for MS prevalence that has been reported from Norway [3,6]. Also here numbers are small, but recent epidemiological and genetic studies suggest that the lower than expected prevalence of MS above the Arctic Circle could be explained by a traditional diet that is rich in vitamin D [5] and possibly by genetic admixture of the ''MS-resistant'' indigenous Sami [4]. Parallels to this situation could probably be found in Alaska, and population-based ecological and genetic studies in this area would be very interesting.Another limitation of the study is that results are based on findings in men only. There is, however, a pronounced and increasing female:male ratio in MS, possibly mediated by epigenetic modifications of HLA-DRB1*15 haplotypes [1]. Recent evidence suggests an interaction between female sex, possibly mediated by oestrogen, and vitamin D in MS [2,7]. References

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“…MS-associated HLA haplotypes are less frequent in the indigenous Sami [3] , and ethnic variations of Fc-␥ receptor and IL-10 polymorphisms between Sami and Norwegian populations have been described [57,58] . In Norway, the first diagnoses of MS in Sami people were made in the early 1990s, and the lowest incidence of MS was found in the most northerly county, Finnmark, where the Sami population is highest [59] .…”

Section: Ms Susceptibility Genesmentioning

confidence: 99%

Vitamin D: A Candidate for the Environmental Effect in Multiple Sclerosis – Observations from Norway

Kampman

Brustad

2008

Neuroepidemiology

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Multiple sclerosis (MS) is a chronic disease of the central nervous system, pathologically characterized by inflammation, demyelination, and axonal damage, presumably auto-immune in nature. Complex interactions between genetic susceptibility and environmental factors, such as vitamin D status and primary Epstein-Barr virus infection in adolescence or later in life, probably determine the MS risk. Norway at a latitude 58–71°N is a discrete exception to the hypothesis that solar UV radiation exposure, mediated by vitamin D, coheres with the latitude gradient seen for MS prevalence. Where UV radiation exposure is low in Norway,vitamin D sufficiency is maintained through a traditional diet providing vitamin D as well as marine omega–3 polyunsaturated fatty acids. This observation supports an environmental interaction between diet and latitude, with vitamin D as the common mediator. The potential roles of vitamin D, other environmental exposures, and genes in the complex aetiology of MS are discussed in this review.

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Low frequency of the disease‐associated DRB115‐DQB106 haplotype may contribute to the low prevalence of multiple sclerosis in Sami

Cited by 37 publications

References 33 publications

Geographical Distribution of Myasthenia Gravis in Northern Europe - Results from a Population-Based Study from Two Countries

Geographical Distribution of Myasthenia Gravis in Northern Europe - Results from a Population-Based Study from Two Countries

Alaska, multiple sclerosis, and the vitamin D hypothesis

Vitamin D: A Candidate for the Environmental Effect in Multiple Sclerosis – Observations from Norway

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