Expression of CD69 in NK cells was higher in the ME/CFS group (p = 0.011), corroborating the observations by Curriu et al. (34) and in contrast to the study by Mihaylova et al. (26) in which they found this activation marker to be lower in ME/CFS patients but after mitogen stimulation, as opposed to the non stimulatory conditions of our and Curriu studies. The gene discussed is CD69; the disease is myalgic encephalomeyelitis/chronic fatigue syndrome.