TH and migraine disorder: Another group Corominas et al. 2009 analysed 50 tag SNPs in 8 genes from the dopaminergic system: DRD1, DRD2, DRD3, DRD5, DBH, COMT, SLC6A3 and TH in two case control populations of Spanish origin and found no evidence of robust genetic association of any of these genes with migraine.