Prothrombin Factor II mutation

Dear Ask The Doctor: In plain language what is this. If 6 cousins (5 female and 1 male have tested positive AND our family has a history of strokes I suspect that many of us have this mutation. I would like to know lay terms, symptoms and test that should be requested. I found medical information but it it very hard to understand. Thank you.

Dear CJ: Prothrombin (factor II) is the precursor of thrombin, the end-product of the clotting pathway. It is a vitamin K-dependent protein which is synthesized in the liver and circulates with a half-life of approximately three to five days. An allele is a genetics term that relates to an alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome. The presence of one copy of this gene mutation increases the risk of the patient developing clots in the leg (Deep Vein Thrombosis), clots in the brain (Cerebral Vein Thrombosis), and stroke in young patients <60 years (arterial thrombosis). The diagnosis of the presence of this mutation can be performed by a blood test using Polymerase Chain Reaction (PCR).