Scientists in Britain have identified a genetic defect linked to migraine which could provide a target for new treatments.
A flawed gene found in a family of migraine sufferers could help trigger the severe headaches, a study in Nature Medicine suggests.
Dr Zameel Cader of the University of Oxford said the discovery was a step forward in understanding why one in five people suffer from migraine, the BBC reports.
Until now, the genes directly responsible for migraine have been unknown.
In this study, scientists found a gene known as TRESK was directly attributable as a cause of migraine in some patients.
The study found that if the gene does not work properly, environmental factors can more easily trigger pain centres in the brain and cause a severe headache.
The international team used DNA samples from families with common migraine to identify the defective gene.
Dr Cader said migraines seem to depend on how excitable the nerves are in specific parts of the brain.
"Finding the key player which controls this excitability will give us a real opportunity to find a new way to fight migraines and improve the quality of life for those suffering," he told the BBC.
Dr Aarno Palotie, from the Wellcome Trust Sanger Institute, said the breakthrough could - in the long term - lead to new drugs which could switch off the pain of migraines.
A migraine is a severe, long-lasting headache usually felt as a throbbing pain at the front or on one side of the head.
Some can have a warning visual disturbance, called an aura, before the start of the headache, and many people also have symptoms such as nausea and sensitivity to light during the headache itself.