Multiple sclerosis in G: genes and geography.

Multiple sclerosis (MS) shows uneven geographic distribution globally as well as within countries. In epidemiological studies we have previously demonstrated that there is a high-risk focus for MS in the southern Ostrobothnian region of western Finland. In genetic studies we recently identified haplotypes that associate with MS specifically in patients originating from southern Ostrobothnia suggesting a founder effect. Such haplotypes can be used as molecular tools for tracing common ancestry between patients in different geographic locations. In addition to providing clues to the historical origin, such a genetic archeological approach should help narrow the size of the shared haplotype, thus facilitating the identification of etiological variants and possibly define a superfamily of MS patients with common pathogenetic mechanisms.

Update of the UMD-FBN1 mutation database and creation of an FBN1 polymorphism database.

Fibrillin is the major component of extracellular microfibrils. Mutations in the fibrillin gene on chromosome 15 (FBN1) were first described in the heritable connective disorder, Marfan syndrome (MFS). FBN1 has also been shown to harbor mutations related to a spectrum of conditions phenotypically related to MFS, called "type-1 fibrillinopathies." In 1995, in an effort to standardize the information regarding these mutations and to facilitate their mutational analysis and identification of structure/function and phenotype/genotype relationships, we created a human FBN1 mutation database, UMD-FBN1. This database gives access to a software package that provides specific routines and optimized multicriteria research and sorting tools. For each mutation, information is provided at the gene, protein, and clinical levels. This tool is now a worldwide reference and is frequently used by teams working in the field; more than 220,000 interrogations have been made to it since January 1998. The database has recently been modified to follow the guidelines on mutation databases of the HUGO Mutation Database Initiative (MDI) and the Human Genome Variation Society (HGVS), including their approved mutation nomenclature. The current update shows 559 entries, of which 421 are novel. UMD-FBN1 is accessible at www.umd.be/. We have also recently developed a FBN1 polymorphism database in order to facilitate diagnostics.

Multiple sclerosis in western Finland: evidence for a founder effect.

We have previously demonstrated that there is a high-risk focus for multiple sclerosis (MS) in the southern Ostrobothnian region of western Finland (population 376121 in 1993). Of the two southern Ostrobothnian health-care districts, Vaasa and Seinäjoki, the incidence and prevalence of MS were especially high in the latter. In recent genetic studies, we identified haplotypes of the myelin basic protein (MBP) gene in a group of MS patients originating from southern Ostrobothnia, suggesting a founder effect. This finding led us to explore the population history of the southern Ostrobothnia and correlate it with MS epidemiology. Southern Ostrobothnia can be divided into three distinct regions with respect to its historical settlement: Vaasa, Seinäjoki-south, and Seinäjoki-north. Vaasa, the coastal region was settled by Swedes, who immigrated during the 13th century. In Vaasa, the prevalence of clinically definite MS (CDMS) in 1993 was 107/10(5) (95% CI 90-124). Seinäjoki-south was populated from the 13th century onwards from southwestern Finland, a region which has been recognised as a high-risk focus of MS. In Seinäjoki-south, the prevalence of CDMS in 1993 was 219/10(5) (95% CI 190-247). Seinäjoki-north was inhabited rather late starting in the 16th century from eastern Finland. In Seinäjoki-north the prevalence of CDMS in 1993 was 136/10(5) (95% CI 108-164). The historical settlement pattern of the southern Ostrobothnia indicates that its population is quite heterogeneous. Seinäjoki-south has a very high prevalence of MS, significantly higher than its two neighbouring regions. The distinctive settlement history of Seinäjoki-south, the historical link with the other southwestern high-risk foci and molecular genetic evidence, suggest that a founder effect plays an important role in the high-risk of MS in western Finland.

A follow-up study of chromosome 19q13 in multiple sclerosis susceptibility.

A possible role of allelic variation on chromosome 19q13 in multiple sclerosis (MS) susceptibility has been suggested. We tested association of sixteen 19q13 markers with MS in 459 families. Nominally significant associations were tested in an independent set of 323 families as well as in the pooled set of 782 families. We were not able to confirm previously suggested associations with APOE, GIPR, ZNF45, ILT6 and D19S585. In the screening dataset nominally significant associations were found with D19S867 and with APOE haplotype (p=0.007 in both), but these were not replicated in the independent dataset nor in the pooled analysis of 757 families. Thus, we were not able to detect any statistically significant allelic associations. Re-sequencing based approaches may be required for elucidating the role chromosome 19q13 with MS.