A new gene linked to "small blood vessel" strokes has been discovered that may improve understanding of the condition.
Researchers identified a gene called FOXF2 which increases the risk of having a stroke due to blocked small blood vessels in the brain.
Previous studies have identified genes linked to strokes caused by reduced blood flow to the brain, and bleeding.
Lead scientist Professor Sudha Seshadri, from Boston University Medical Center in the US, said: "Unravelling the mechanisms of small vessel disease is essential for the development of therapeutic and preventive strategies for this major cause of stroke."
The research highlights a novel biological pathway affecting pericytes, a type of cell in the walls of small arteries and capillaries.
Small blood vessel disease in the brain is also a major contributor to dementia risk and is associated with gait problems and depression, the scientists said.
The findings are published in the journal The Lancet Neurology.