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A cluster of multiple sclerosis cases in Lysvik in the Swedish county of Värmland
Linköping University, Department of Neuroscience and Locomotion, Neurology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Neuroscience and Locomotion, Neurology. Linköping University, Faculty of Health Sciences.
2004 (English)In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 110, no 1, 14-22 p.Article in journal (Refereed) Published
Abstract [en]

Objectives – When surveying the county of Värmland in Sweden in order to determine the prevalence of multiple sclerosis (MS), we observed an aggregation of MS cases originating from the parish of Lysvik in the local region called Fryksdalen. Our intention was to analyse this cluster thoroughly, confirming the MS diagnosis and seeing if a hereditary or environmental background was plausible.

Methods – The medical files were studied and the cases were classified by a neurologist according to Poser's criteria. Hereditary factors were analysed.

Results – Sixteen living cases of MS were found, either living in the parish (n = 6) or born or raised there and had later moved to another place (n = 10). All patients had clinically definite MS. Eleven patients had relatives with MS, all of these being descendants of the Suhoinen family. Another two cases were Suhoinen descendants who did not have relatives with MS. Other common ancestors were also identified. Two cases were adopted. Eleven deceased MS patients from Lysvik were found, 10 of them had Suhoinen ancestry.

Conclusion – We report a cluster of MS cases with a common ancestry indicating heredity for MS in 85% of the cases. Lysvik is a parish where Finnish immigration was pronounced in the 17th century and there has been inbreeding to a certain extent through marriage between cousins. Thus, we interpret this aggregation as possibly being genetically based, and neurogenetic studies are now being performed. However, as two of the cases were adopted environmental factors must also be considered.

Place, publisher, year, edition, pages
2004. Vol. 110, no 1, 14-22 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-28710DOI: 10.1111/j.1600-0404.2004.00266.xLocal ID: 13879OAI: diva2:249521
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-10-23Bibliographically approved
In thesis
1. Epidemiological and genetic studies of muliple sclerosis with focus on the Swedish county of Värmland
Open this publication in new window or tab >>Epidemiological and genetic studies of muliple sclerosis with focus on the Swedish county of Värmland
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aim of this study was to perform detailed investigations of a presumed high-risk area, namely the county of Värmland, to see if previous results from our group indicating a high frequency of multiple sclerosis (MS) could be confirmed. We soon identified an aggregation of MS cases in the parish of Lysvik located in the north of Värmland and initiated epidemiological and genetical analyses of the population. We also extended our genetic research to include studies of a possible association between MS immunopathic trait and the MS susceptibility gene HLA-DR(2)15 type, but in another geographic area.

The onset-adjusted prevalence of MS in Värmland was 170/105 (95% CI: 154-185) in December 2002, which is higher than prevalence previously reported from other Swedish areas. There was a great variation in MS frequency between communities in Värmland. We found a persistently high occurrence of MS in Torsby and Sunne communities. In the community of Årjäng MS frequency had increased substantially since the previous study performed by our group.

Epidemiological analysis of a cluster of MS cases in Lysvik revealed 27 MS patients, of whom 23 were the descendants of a Finnish family originated from a common ancestor born in Savolaks in Finland in the 16th century and 18 had relatives with MS. Since this cluster was most likely to have a genetic basis (located in an area with a high inbreeding rate) the mode of MS inheritance was investigated. The linkage study using the genome-wide transmission disequilibrium test (TDT) provided several regions of interest, especially on chromosome 14q (14q24-31). The linkage peak on chromosome 17q was also confirmed by this study.

The frequency of the HLA-DR(2)15 allele was higher in healthy siblings of MS patients without MS immunopathic trait (MSIT) than in siblings with the trait, which provides further support for the hypothesis that MSIT and MS are two independent, albeit, synergistic conditions.

The prevalence study supports that Värmland County is a high-risk area. Furthermore, the aggregation of MS cases in Lysvik indicates a concentrated risk zone, possibly due to a combination of genetic, environmental and social risk factors. A widely and evenly spread environmental (i.e., infectious) agent together with cultural changes and industrialisation could possibly induce disease in subgroups of genetically more susceptible individuals. The evidence of linkage to chromosome 14 found in this study indicates that further genetic research is required.

Place, publisher, year, edition, pages
Linköping: Institutionen för nervsystem och rörelseorgan, 2006. 60 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 949
Inborn genetic diseases, Genetic predisposition to disease, Genetic predisposition to disease, Cluster analysis, Muliple sclerosis, Pedigree
National Category
Medical Genetics
urn:nbn:se:liu:diva-7444 (URN)91-85497-86-X (ISBN)
Public defence
2006-06-01, Elsa Brändströms sal, Södra ingången, plan 10, Campus US, Linköpings Universitet, Linköping, 13:00 (English)
Available from: 2006-09-27 Created: 2006-09-27 Last updated: 2012-10-23Bibliographically approved

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Callander, MargaritaLandtblom, Anne-Marie
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