The MS population has an increased disease mortality, while the increase in the risk of accidents and suicides is not significantly increased among patients with MS in Finland.

Previous surveys in Finland from the 1960s have documented an uneven geographic distribution of multiple sclerosis (MS). In the present study, the incidence of MS was studied during 1979–1993 in the western Vaasa and Seinäjoki regions and in southern Uusimaa. The overall difference between the western and southern regions persisted; 8.7 per 100,000 in the western, and 5.1 per 100,000 in the southern region. The incidence of 11.6 per 100,000 in Seinäjoki was more than twofold greater than the 5.2 per 100,000 incidence found in neighboring Vaasa. An increasing incidence trend was observed for men in Seinäjoki, and a decrease for both sexes in Vaasa, while in Uusimaa the incidence remained stable for both sexes. The different incidence trends could not be readily explained by differences in case ascertainment but suggest the effect of environmental factors that have modulated the incidence of MS during the 15-year study period.

The results were sensitive only to large changes in analysis perspective or MTC. Based on the analyses, teriflunomide was cost-effective versus BSC or DMF with the common threshold values, was dominant versus other first-line RRMS treatments, and provided the greatest impact on investment. Teriflunomide is potentially the most cost-effective option among first-line treatments of RRMS in Finland.

Central Finland represents an average risk area of MS when compared with other areas of Finland but still a high risk in global comparison. The recent rapid increase in both prevalence and incidence is largely accounted for by increased use of MRI.

The risk of cancer among multiple sclerosis (MS) patients was evaluated emphasising cancers with a potentially infectious aetiology. Cancer incidence was estimated among incident MS patients in 1964–1993 (n = 1,597) in Finland. The cohort was followed up for cancer incidence through the Finnish Cancer Registry until 1999. A total of 85 cancer cases were diagnosed showing a standardised incidence ratio (SIR) of 1.0 (95% CI 0.8–1.2) for all cancers. The risk (SIR) of haematological tumours was 1.1 and that of central nervous system (CNS) tumours 1.3. The small excess risk of haematological malignancies is consistent with infectious aetiology, whereas the association between MS and CNS tumours may be due to misclassification.

Objective To study the position of hemiplegic migraine in the clinical spectrum of migraine with aura and to reveal the importance of CACNA1A, ATP1A2 and SCN1A in the development of hemiplegic migraine in Finnish migraine families. Methods The International Classification of Headache Disorders 3rd edition criteria were used to determine clinical characteristics and occurrence of hemiplegic migraine, based on detailed questionnaires, in a Finnish migraine family collection consisting of 9087 subjects. Involvement of CACNA1A, ATP1A2 and SCN1A was studied using whole exome sequencing data from 293 patients with hemiplegic migraine. Results Overall, hemiplegic migraine patients reported clinically more severe headache and aura episodes than non-hemiplegic migraine with aura patients. We identified two mutations, c.1816G>A (p.Ala606Thr) and c.1148G>A (p.Arg383His), in ATP1A2 and one mutation, c.1994C>T (p.Thr665Met) in CACNA1A. Conclusions The results highlight hemiplegic migraine as a clinically and genetically heterogeneous disease. Hemiplegic migraine patients do not form a clearly separate group with distinct symptoms, but rather have an extreme phenotype in the migraine with aura continuum. We have shown that mutations in CACNA1A, ATP1A2 and SCN1A are not the major cause of the disease in Finnish hemiplegic migraine patients, suggesting that there are additional genetic factors contributing to the phenotype.

Complex traits, including migraine, often aggregate in families, but the underlying genetic architecture behind this is not well understood. The aggregation could be explained by rare, penetrant variants that segregate according to Mendelian inheritance or by the sufficient polygenic accumulation of common variants, each with an individually small effect, or a combination of the two hypotheses. In 8,319 individuals across 1,589 migraine families, we calculated migraine polygenic risk scores (PRS) and found a significantly higher common variant burden in familial cases (n = 5,317, OR = 1.76, 95% CI = 1.71-1.81, p = 1.7 × 10) compared to population cases from the FINRISK cohort (n = 1,101, OR = 1.32, 95% CI = 1.25-1.38, p = 7.2 × 10). The PRS explained 1.6% of the phenotypic variance in the population cases and 3.5% in the familial cases (including 2.9% for migraine without aura, 5.5% for migraine with typical aura, and 8.2% for hemiplegic migraine). The results demonstrate a significant contribution of common polygenic variation to the familial aggregation of migraine.

In the original publication of this paper, the middle initial of Michael D. Ferrari's name was inadvertently left out. This has since been corrected online. The authors apologize for the error.