A number of observations, including among our study population, have implicated variants in the
syntaxin-1A, a component of the synaptic vesicles, in
migraine susceptibility. Therefore, we hypothesize that variants in other components of the vesicle machinery are involved in
migraine.
BACKGROUND:
Migraine is a common and complex
neurologic disorder that affects approximately 15-18% of the general population. The exact cause of
migraine is unknown; however, genetic studies have made possible substantial progress toward the identification of underlying molecular pathways.
Neurotransmitters have been for long considered to have a key role in
migraine pathophysiology; so we investigated common variants in genes involved in the synaptic vesicle machinery and their impact in
migraine susceptibility.
METHODS: We performed a case-control study comprising 188 unrelated patients with
headache and 286 healthy controls in a population from the north of Portugal. Benefiting from the presence of linkage disequilibrium, we selected and genotyped 119 tagging single-nucleotide polymorphisms in 18 genes.
RESULTS: We found significant associations between single-
nucleotide variants and
migraine in 7 genes, SYN1, SYN2, SNAP25,
VAMP2, STXBP1, STXBP5, and UNC13A, either conferring an increased risk or protection of
migraine. Due to SYN1 X-chromosomal location, we performed the statistical analysis separated by gender and, in the female group, the C allele of rs5906435 increased the risk for
migraine susceptibility (P = .021; OR = 1.69; 95% CI: 1.21-2.34). In contrast, the TT genotype of the same variant emerged as a potential protective factor (P = .003; OR = 0.45; 95% CI: 0.27-0.74). The SYN2 analysis supported the rs3773364's G allele (P = .014) as a risk factor for
migraine, and although not statistically significant after correction, the AG genotype (P = .006; OR = 1.86; 95% CI: 1.20-2.90) reinforced the allelic findings. Additionally, we found the SNAP25-rs363039's CT genotype (P = .001; OR = 2.14; 95% CI: 1.36-3.34), the STXBP5-rs1765028's T allele (P = .041; OR = 1.46; 95% CI: 1.13-1.90), and the UNC13B-rs7851161's TT genotype (P = .001; OR = 2.14; 95% CI: 1.36-3.34) as statistically significant risk factors for
migraine liability. VAMP2-rs1150's G allele revealed a risk association to
migraine, not statistically significant after correction (P = .068). Additionally, we found haplotypes in SYN1, SYN2, STXBP1, and UNC13B to be associated with
migraine.
CONCLUSIONS: Overall, this study provides a new insight into
migraine liability, identifying possible starting points for functional studies.