BDNF and migraine disorder: The SNP rs1553005 of the latter gene has been found to interact with the variant rs2049046 of the gene encoding brain-derived neurotrophic factor (BDNF) increasing the risk of migraine [rs1553005(CGRP)*rs2049046(BDNF) = GC*AT – OR 1.88 (95 %CI 1.20–2.93), P = 0.005] [42].