Since you ask, Dr. Afrin, I think that in the case of ME it is triggered by an infection
I am old-school and do better with real paper books.
I also wonder if he talks about EDS? there tends to be a predisposition in people with EDS III. I think looking back I can probabaly see warning signs in childhood also, but it didn't kick off for me until a couple of years ago - first three months of not being able to hardly breathe and having to stay in bed for three months because I couldn't walk or stand up and breathe, and steroids and asthma meds did nothing for it, then straight after this a dose of doxycycline kicked off the 24 hr a day itching...