I am currently waiting for results from a genetic mitochondrial disease that runs in my family. I was diagnosed with POTS, but after doing POTS protocol for a month they determined it's not true POTS, but POTS like symptoms. I have been fully worked up by Pulmonary and did the Pulmonary exercise test...I passed, but barely, but I passed, so they said it's not Pulmonary. With all of the different symptoms I have...they think it's mitochondrial or stemming from my nervous system not functioning properly. I still have more testing to do like a muscle biopsy if the genetic test is negative. Not giving up. (I do NOT have sleep apnea. I'm on oxygen for nocturnal hypoxemia without apnea. Hope this helps.