Increases in P2X4, P2X5, TRPV1, and ASIC3 plus exaggerated COMT, α-2A, and β-2 adrenergic receptor expression following moderate exercise have been a unique profile in CFS and CFS+FMS patients, not evident in any other patient group with chronic fatigue or pain that we have examined to date. This evidence concerns the gene P2RX4 and myalgic encephalomeyelitis/chronic fatigue syndrome.