Several genes involved in vascular functions, such as endothelin-1 (ETA-1), angiotensin-converting enzyme (ACE), Neurogenic Locus Notch Homolog Protein 4 (NOTCH4) and methylenetetrahydrofolate reductase (MTHFR) genes have been studied in patients with primary headaches and some of these, such as the MTHFR gene, were significantly associated with migraine [19-24]. Here, NOTCH4 is linked to migraine disorder.