Molecular basis of the irritable bowel syndrome

Table 1 Genetic alterations on irritable bowel syndrome

Gene	Polymorphism	Ref.
Serotonergic system
SERT promoter	5-HTTLPR, deletion	[13-17]
	rs25531	[81]
HTR3A	-42C > T	[50]
HTR3B	386A > C	[82]
HTR3C	489C > A	[83]
HTR3E	rs62625044	[50]
Adrenergic and opioidergic system
α2-adrenergic receptor	α2C del 322-325, deletion	[19]
	α2A-1291C > G	[19,84]
COMT	α2A-1291 C > G	[20]
	Val158Met	[21,22]
CNR1	(AAT)n triplet repeat	[23]
	rs806378	[24]
CRH-R1	rs7209436	[27]
	rs242924	[27]
BDNF	Val166Met	[85]
OPRM1	118A > G	[85]
Cytokines
IL-10	-1082 A > G	[28-30]
	396 T > G	[30]
	-819T > G	[34]
TNF alpha	-308G > A	[28]
	-238G > A	[86]
GNβ3	825C > T	[32]
TLR9+	-1237T > C	[84]
	2848 G> A	[84]
IL1R	Pst-I 1970C > T	[86]
IL4	-590C > T	[84,87]
	-33T	[87]
IL6	-174G > C	[84,86]

SERT: Serotonin reuptake transporter; COMT: Catechol-O-methyltransferase; CNR1: Cannabinoid receptor 1; CRH-R1: CRH receptor 1; IL: Interleukin; TNF: Tumor necrosis factor.