Scientists have identified a 'migraine gene', raising hopes of new drugs to nip the crippling headaches in the bud.
Migraines feature in the World Health Organisation's top 20 most disabling lifetime conditions and affect one in eight men and women.
They lead to more sick days than any other illness - at a cost to the economy of more than £2billion a year.
The intense headaches, which can be accompanied by nausea and visual disturbances, as well as sensitivity to light, can take up to three days to pass, and one in seven sufferers believes that time off due to migraines has affected their career.
With current drugs not effective or not suitable for all sufferers, the latest breakthrough could make the condition more bearable for millions.
An international research team, spearheaded by experts from the Wellcome Trust Sanger Institute, in Cambridge, compared the DNA of thousands of migraine sufferers with that of other people.
This highlighted a genetic flaw that appears to raise the odds of the disease by allowing glutamate, a chemical that transmits messages in the brain, to build up in the junctions between brain cells.
Drugs that stop glutamate from accumulating could halt migraines, the journal Nature Genetics reports. Although past research has identified genes linked to rare forms of migraine, never before has one behind the most common form of the condition been found.
Dr Aarno Palotie, of the Sanger Institute, said: 'This is the first time we have been able to peer into the genomes of many thousands of people and find genetic clues to understand common migraine.
'Studies of this kind are possible only through large-scale international collaboration - bringing together the wealth of data with the right expertise and resources - so that we could pick out this genetic variant.
'This discovery opens new doors to understand common human diseases.'
Professor Christian Kubisch, of the University of Ulm, Germany, said: 'This research paves the way for new studies to look in depth at the biology of the disease and how this alteration may exert its effect.'
Professor Peter Goadsby, trustee of the Migraine Trust, said: 'The results of this large study of migraine sufferers brings us a little closer to understanding some fundamental aspects of the disorder, implicating an important chemical in the brain, glutamate, which turns on nerve cells.
'Such findings bring hope for new research directions to find better treatments for migraine.'
