I am just wondering. My wife (she's the one who is sick, not me) has POTS, but we are still awaiting XMRV test kits. Knowing that many CFS sufferers have some form of orthostatic intolerance, but of differing types, I am suddenly wondering if XRMV-positive status is corresponding to some types of OI but not others. (BTW -- what ever happened to that survey that would elicit the varying symptoms and diagnoses of XMRV-positive people?) The finding that XMRV may tend to take up residence in smooth muscle tissue makes me wonder if that could be why a POTS sufferer's peripheral (legs particularly) blood vessels mysteriously fail to contract properly, even as their nervous system is screaming (releasing lots of norepinephrine). I'll be very interested in the results of the Vanderbilt study. Thanks in advance for all responses!