A replication study of GWAS findings in migraine identifies association in a Swedish case-control sample

Background: Migraine is a common neurovascular disorder with symptoms including headache of moderate to severe intensity and recurring attacks. There is no cure for migraine today and the pathology is poorly understood. Common forms of migraine have a complex genetic background and heritability has been estimated to be around 50%. Recent genome-wide association studies (GWAS) on European and American migraine cohorts have led to the identification of new genetic risk factors for migraine. Methods: We performed an association study in a Swedish population based cohort, investigating the frequency of eight single nucleotide polymorphisms (SNPs) recently identified as genetic risk factors for migraine in three GWAS, using available array data (Illumina Omni Express chip). The eight SNPs were rs2651899, rs3790455, rs10166942, rs7640543, rs9349379, rs1835740, rs6478241 and rs11172113. Because information on rs3790455, rs10166942 and rs7640543 was not directly available, we selected SNPs in high Linkage Disequilibrium (LD) with these three SNPs, and replaced them with rs2274316, rs1003540 and rs4075749, respectively. Results: We were able to replicate the association with rs2651899 and found a trend for association with rs1835740 in our Swedish cohort. Conclusions: This is the first reported genetic association study of a Swedish migraine case control material. We have thus replicated findings of susceptibility loci for migraine in an independent genetic material, thereby increasing knowledge about genetic risk factors for this common neurological disorder.