Miao J et al. [18] performed a meta-analysis to determine if polymorphisms in genes linked to the vascular system could be related to migraine. They focused their attention on the receptor for endothelin-1, (EDNRA) known as a potent vasoconstrictor investigating the EDNRA -231G > A SNP. Three studies were included in their meta-analysis for a total of 440 migraineurs, 222 subjects with tension-type headaches (TTHs) and 1323 controls. They found statistical difference between migraineurs and controls with AA genotype vs. AG + GG, suggesting a potential association of -231G > A SNP and migraine. These data suggest that individual SNPs will provide only a small piece of a much larger puzzle composed by a variety of (un) know clinical (phenotypic) information.