Genetic TPH2 variants and the susceptibility for migraine: association of a TPH2 haplotype with migraine without aura

The serotonergic system plays a major role in the etiology of migraine. The rate-limiting enzyme in serotonin homeostasis and availability is tryptophan hydroxylase (TPH). The TPH2 isoform is responsible for the cerebral serotonin biosynthesis. To investigate the role of genetic variation in TPH2 in the pathogenesis of migraine eight haplotype tagging SNPs covering the whole TPH2 gene where chosen using Haploview and genotyped in 503 migraineurs and 515 healthy controls. Association analysis was performed on a single SNP and haplotype basis using chi (2) and logistic regression analysis. Single SNP analysis revealed a weak association with migraine, which did not remain after correction for multiple testing. Haplotype analyses revealed association of a haplotype with migraine without aura. Stratification by aura and triptan response did not reveal a positive association with the investigated polymorphisms. These results suggest a possible influence of genetic variation in TPH2 in the pathogenesis of migraine.