5hmC	5-Hydroxymethylcytosine
5hmdC	5-hydroxymethyl-2′-deoxynytidine
5hmdC	Global DNA hydroxy methylation
5mC	5-Methylcytosine
5mdC	Global DNA methylation
ARC	American College of Rheumatology Criteria
BAI	Beck Anxiety Index
BDNF	Brain-derived neurotrophic factor
BMI	Body mass index
C-CPM	Cold effect on conditioned pain modulation
COMT	Catecholamine-O-methyltransferase
CpG	Cytosine-phosphate-Guanine dinucleotide
CPM	Conditioned pain modulation
CPT	Cold pain thresholds
CSI	Central sensitization inventory
CSL	CFS symptom list for ME/CFS-related symptoms
DNA	Deoxyribonucleic acid
DNMT3a	DNA methyltransferase 3a
EM-Seq	Enzymatic methyl-sequencing
FM	Fibromyalgia
fMRI	Functional magnetic resonance imaging
H-CPM	Heat effect on conditioned pain modulation
HDAC1	Histone deacetylase 1
HPLC	High-pressure liquid chromatography
HPT	Heat pain thresholds
IPAQ	International physical activity questionnaire
LC/MS-MS	Liquid chromatography and tandem mass spectrometry
MB-COMT	Membrane-bound COMT
MBD1	Methyl-CpG-binding domain 1
ME/CFS	Myalgic encephalomyelitis/chronic fatigue syndrome
MeCP2	Methyl-CpG-binding proteins
METs	Metabolic equivalents
MOR	µ-Opioid receptor 1
mRNA	Messenger RNA
NRS	Numeric Rating Scale
OPRM1	µ-Opioid receptor 1 gene
PCA	Principal component analysis
PCR	Polymerase chain reaction
PCS	Pain catastrophizing scale
PET	Positron emission tomography
PPT	Pressure pain threshold
QST	Quantitative sensory testing
RM-LMM	Repeated-measures linear mixed model
S-COMT	Soluble COMT
SF-36	Short-form 36 questionnaire
TAPSß	TET-assisted pyridine borane sequencing
VIF	Variance inflation factor
WPI	Widespread Pain Index