Lower COMT activity has in fact been associated with increased catecholamine levels in the brain, which in turn have been associated with pain, hyperalgesia, and increased susceptibility to infections [6, 19, 20], all established features of CFS/FM.[25, 32] Our results are in line with these findings, as we showed the low-activity haplotype to be associated with symptoms in both patients with CFS/FM and healthy controls. This evidence concerns the gene COMT and myalgic encephalomeyelitis/chronic fatigue syndrome.