The prevalence of neurological symptoms and neuro-muscular pain in MCS, FM, and CFS has also directed investigations towards COMT polymorphisms, since COMT genetic and epigenetic factors are implicated in the impairment of catecholamine regulation, of cognitive tasks, and in the disregulation of nociceptive signalling of NF-kB [103]. This evidence concerns the gene COMT and myalgic encephalomeyelitis/chronic fatigue syndrome.