ITGAL and cyclic hematopoiesis: Based on the strength of association to a successful verapamil treatment of migraine [43], and a potential role for the corresponding gene in CH pathophysiology, we selected four markers in four different genes; rs17844444 in protocadherin β6 (PCDHB6), rs10882386 in phospholipase C ε1 (PLCE1), rs1531394 in anoctamin 3 (ANO3), and rs2230433 in α subunit of integrin lymphocyte function associated antigen-1 (ITGAL).