Yet, ME/CFS patients seem to have normal NO alongside with normal IL-6 levels, before and after a physical exercise upon fatigue symptoms but exhibit high levels of F2-isoprostanes, which are oxidative stress biomarkers, probably quenched by the activity of ozone on the Nrf2/Keap1/ARE system [47,48,49]. The gene discussed is KEAP1; the disease is myalgic encephalomeyelitis/chronic fatigue syndrome.