DRD2 and cyclic hematopoiesis: Studies addressing genetic factors underlying treatment response to triptans have described GNB3 C825T gene polymorphism to be associated with a better response to triptans in CH patients, and polymorphisms in the PRDM16, SLC6A4 and DRD2 genes to be associated with a better, inconsistent and worse response to triptans in migraine patients, respectively [183].