Cross-trait analyses identify shared genetics between migraine, headache, and glycemic traits, and a causal relationship with fasting proinsulin

The co-occurrence of migraine and glycemic traits has long been reported in observational epidemiological studies, but it has remained unknown how they are linked genetically. We used large-scale GWAS summary statistics on migraine, headache, and nine glycemic traits in European populations to perform cross-trait analyses to estimate genetic correlation, identify shared genomic regions, loci, genes, and pathways, and test for causal relationships. Out of the nine glycemic traits, significant genetic correlation was observed for fasting insulin (FI) and glycated haemoglobin (HbA1c) with both migraine and headache, while 2-h glucose was genetically correlated only with migraine. Among 1703 linkage disequilibrium (LD) independent regions of the genome, we found pleiotropic regions between migraine and FI, fasting glucose (FG), and HbA1c, and pleiotropic regions between headache and glucose, FI, HbA1c, and fasting proinsulin. Cross-trait GWAS meta-analysis with glycemic traits, identified six novel genome-wide significant lead SNPs with migraine, and six novel lead SNPs with headache (P-meta < 5.0 x 10(-8) and Psingle-trait < 1 x 10(-4)), all of which were LD-independent. Genes with a nominal gene-based association (P-gene <= 0.05) were significantly enriched (overlapping) across the migraine, headache, and glycemic traits. Mendelian randomisation analyses produced intriguing, but inconsistent, evidence for a causal relationship between migraine and headache with multiple glycemic traits; and consistent evidence suggesting increased fasting proinsulin levels may causally decrease the risk of headache. Our findings indicate that migraine, headache, and glycemic traits share a common genetic etiology and provide genetic insights into the molecular mechanisms contributing to their comorbid relationship.

Automated summary

The co-occurrence of migraine and glycemic traits has been observed in epidemiological studies, and this study aimed to investigate the genetic link between them. Cross-trait analysis of GWAS data revealed genetic correlations and shared genomic regions between migraine, headache, and various glycemic traits. Novel genetic markers associated with migraine and headache were identified, and gene-based association analyses showed overlaps across migraine, headache, and glycemic traits. Mendelian randomization analyses provided intriguing but inconsistent evidence for causal relationships. These findings shed light on the common genetic factors and molecular mechanisms underlying the comorbidity of migraine, headache, and glycemic traits.