5-HTTLPR polymorphism in the serotonin transporter gene and migraine: A systematic review and meta-analysis

Background and methods: Data on the association between the SLC6A4 5-HTTLPR polymorphism and migraine are conflicting. We performed a systematic review and meta-analysis among studies published up to September 2009. For each study with genotype information, we calculated odds ratios (OR) and 95% confidence intervals (CI) assuming additive, dominant, and recessive genetic models. We then calculated pooled ORs and 95% CIs. Results: Among the ten studies identified there was no overall association between the polymorphism and any migraine for Europeans or Asians. However, European women carrying the S allele had an increased risk for any migraine (dominant model: pooled OR = 2.02; 95% CI 1.24-3.28). Results among Europeans further suggested an increased risk for migraine with aura among carriers of the S/S genotype (recessive model: pooled OR = 1.41; 95% CI 0.83-2.40). Conclusions: While our results indicate no overall association between the SLC6A4 5-HTTLPR polymorphism and migraine among Europeans and Asians, gender and migraine aura status may have modifying roles among Europeans.