A cluster of multiple sclerosis cases in Lysvik in the Swedish county of Varmland

Abstract

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.

High inbreeding in the Faroe Islands does not appear to constitute a risk factor for multiple sclerosis

“…The high-prevalence regions found in northern Sweden and western Finland where ties of kinship were found in 22 out of 33 patients and in approximately 85% of cases respectively were also calculated from pedigree data. 10,11 This can give only expected and not a true degree of relatedness. Nevertheless other possible explanations for the inconsistent findings cannot be ruled out.…”

An ecological study of industry in a high-risk region of multiple sclerosis

“…It is also important to consider the possibility of gene-environment interaction and, in fact, there are indications that this might be the case in the cluster of Lysvik, situated in the high-risk county of Värmland [22]. A large pedigree of descendants from the Finnish immigrant Povel Suhoinen, born in 1584, suggested a genetic component of this cluster.…”

“…Eighty-one percent of the MS patients in the cluster had the same ancestor, and of these 69% had relatives with MS. There were 16 MS patients born and/or raised in the cluster of Lysvik in the Fryksdal valley (1759 population in 1997) [22].…”

“…The highest rate (per year) was found in the most northern municipalities of Sunne (5.16 per 100,000) and Torsby (4.99 per 100,000). An interesting observation and a possible link of MS is a sawmill [21] in the high-risk cluster of Lysvik in the Fryksdal region of the county [22]. This sawmill, probably led to the presence of pentachlorophenol in soil and water [23].…”

Further considerations on the distribution of multiple sclerosis in Sweden

“…7) which to some extent resembles the data from Sällström/Kurtzke. There is no doubt regarding the high‐risk zone Fryksdalen (Torsby and Sunne communities), where a cluster (Lysvik) recently has been described (14).…”