U.S. scientists have found three genes linked to crippling migraine headaches, including one that explains why women are the primary sufferers.

The findings appear in the British journal Nature Genetics.

The team of scientists from Harvard Medical School found variations in three genes common in migraine sufferers.

Migraines are painful debilitating headaches whose symptoms often include nausea and an unbearable sensitivity to light. The exact cause of migraines is unknown.