Genome-wide association studies have implicated a common genetic variant in chromosome 6p24 in coronary artery disease, as well as four other vascular diseases: migraine headache, cervical artery dissection, fibromuscular dysplasia, and hypertension. However, it has not been clear how this polymorphism affects the risk for so many diseases. Researchers show how this DNA variant enhances the activity of a gene called endothelin-1, which is known to promote vasoconstriction and hardening of the arteries.