Migraine is a debilitating neurological disorder affecting around 1 in 7 people worldwide, but its molecular mechanisms remain poorly understood. Some debate exists over whether migraine is a disease of vascular dysfunction or a result of neuronal dysfunction with secondary vascular changes. Genome-wide association (GWA) studies have thus far identified 13 independent loci associated with migraine. To identify new susceptibility loci, we performed the largest genetic study of migraine to date, comprising 59,674 cases and 316,078 controls from 22 GWA studies. We identified 44 independent single nucleotide polymorphisms (SNPs) significantly associated with migraine risk (P < 5 × 10−8) that map to 38 distinct genomic loci, including 28 loci not previously reported and the first locus identified on chromosome X. In subsequent computational analyses, the identified loci showed enrichment for genes expressed in vascular and smooth muscle tissues, consistent with a predominant theory of migraine that highlights vascular etiologies.

Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology.

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Migraine without aura is the most common form of migraine, characterized by recurrent disabling headache and associated autonomic symptoms. To identify common genetic variants for this migraine type, we analyzed genome-wide association data of 2,326 clinic-based German and Dutch patients and 4,580 population-matched controls. We selected SNPs from 12 loci with two or more SNPs with P-values < 1 × 10 −5 for follow-up in 2,508 patients and 2,652 controls. Two loci, i.e. 1q22 (MEF2D) and 3p24 (near TGFBR2) replicated convincingly (P = 4.9 × 10 −4 , P = 1.0 × 10 −4 , respectively). Meta-analysis of the discovery and replication data yielded two additional genome-wide significant (P < 5 × 10 −8 ) loci in PHACTR1 and ASTN2. In addition, SNPs in two previously reported migraine loci in or near TRPM8 and LRP1 significantly replicated. This study reveals the first susceptibility loci for migraine without aura, thereby expanding our knowledge of this debilitating neurological disorder. Main textMigraine is a disabling episodic neurovascular brain disorder affecting 12% of the general population [1][2][3][4] . Migraine attacks are typically characterized by severe throbbing unilateral headache and nausea, vomiting and photo-and phonophobia (migraine without aura; MO). In up to one third of patients attacks may be associated with neurological aura symptoms (migraine with aura; MA). Previous genome-wide association studies (GWAS) identified a migraine susceptibility locus on chromosome 8q22, close to MTDH, in the clinic-based International Headache Genetics Consortium (IHGC) MA study 5 and three other loci in or near PRDM16, LRP1, and TRPM8 in the population-based migraine Women's Genome Health Study (WGHS) 6 . For TRPM8 there was suggestive association (P < 1 × 10 −5 ) also in the clinic-based IHGC MA GWAS 5 . Here we report the first GWAS in MO, the most common form of migraine. We analyzed two large samples from headache centres in Germany and the Netherlands including 2,326 MO patients and 4,580 population-matched controls (Supplementary Note and Supplementary Fig. 1). A quantile-quantile plot of the joint analysis ( Supplementary Fig. 2) and an overall inflation factor ( 1000) of 1.03 were used as final quality control measures. The discovery dataset identified one genome-wide significant (P < 5 × 10 −8 ) locus on chromosome 1q22 as well as eleven additional loci containing multiple SNPs with suggestive association (P < 1 × 10 −5 ) (Supplementary Table 1). Eighteen SNPs from these 12 loci were taken forward to the replication stage in four Fig. 1 and Supplementary Table 1). Eight SNPs in six loci showed P-values < 0.05 in the replication study, and five of these SNPs also showed P-values < 5 × 10 −8 in the meta-analysis combining the discovery and replication cohorts (Table 1, Fig. 1 and Supplementary Fig. 3). Four loci (1q22, 3p24, 6p24, 9q33) replicated, although replication was less convincing for loci on 6p24 and 9q33 with replication P-values of 0.012 and 0.018, respectively, although P-values were < 5 × ...

Migraine affects over a billion individuals worldwide but its genetic underpinning remains largely unknown. Here, we performed a genome-wide association study of 102,084 migraine cases and 771,257 controls and identified 123 loci, of which 86 are previously unknown. These loci provide an opportunity to evaluate shared and distinct genetic components in the two main migraine subtypes: migraine with aura and migraine without aura. Stratification of the risk loci using 29,679 cases with subtype information indicated three risk variants that seem specific for migraine with aura (in HMOX2, CACNA1A and MPPED2), two that seem specific for migraine without aura (near SPINK2 and near FECH) and nine that increase susceptibility for migraine regardless of subtype. The new risk loci include genes encoding recent migraine-specific drug targets, namely calcitonin gene-related peptide (CALCA/CALCB) and serotonin 1F receptor (HTR1F). Overall, genomic annotations among migraine-associated variants were enriched in both vascular and central nervous system tissue/cell types, supporting unequivocally that neurovascular mechanisms underlie migraine pathophysiology.