Hello -- The ankle/calf problem should not in any way be related to the benign familial hematuria ("thin membrane disease" otherwise known). This sounds actually fairly normal, although there could be some sort of poor venous return causing his distended vein you've noticed. Of course it's also possible a sensation in the area only caused you to pay attention and notice this vein, which may have been there all along. If there is pain or swelling in the area it needs to be evaluated by a doctor, but otherwise I suspect it is just a muscle tightness, possible slight soft-tissue injury not noticed when it occurred. Again, any swelling, pain or discoloration means it should me medically evaluated. It has no relation to thin membrane disease nor should it have anything to do with high blood pressure.
I hope this is helpful to you. Good luck to you and please follow up with us here as needed.
John Kenyon, EMT, CCT
Non-invasive cardiology tech, Emergency and Critical Care technician, Critical Incident Stress Mgmt. specialist