What genes play an important role in stroke?

Rarely one gene: Most strokes are due to risk factors such as hypertension, diabetes, and cholesterol issues have a genetic component that usually isn't localized to one gene. Familial clusters of strokes due to a single gene (eg cadasil) or single mitochondrial RNA mutation (eg melas) are rare.

Many: There is no "stroke gene". There are many conditions which are genetically determined, such leiden factor v deficiency which leads to stroke. If you have strong family history of stroke, you should find out what condition(s) your family has contributing to their strokes. This is a more productive approach than searching the human genome.