Table 1.

Gene Polymorphisms in Rheumatoid Arthritis (RA)

Gene Symbol	Polymorphism Position	Alleles	Possible Effect of Polymorphism	References
TNFα	+1304	G A	May contribute to the susceptibility to RA / Possible linkage disequilibrium	[22]
	+489	G A	More severe erosive disease	[16]
	-238	G A	More severe articular erosions Less severe articular erosions	[20]
	-308	G A	Normal production of TNFα Up-regulation of TNFα production	[19, 18]
	-857	C T	May contribute to the susceptibility to RA / High TNFα production	[23]
	-863	C A	May contribute to the susceptibility to RA / High TNFα production	[21]
	-1031	T C	May contribute to the susceptibility to RA / High TNFα production	[22, 24]
	TNFa6;b5;c1;d3;e3		Increased susceptibility to RA	[29]
TNFRSF1B	codon 196	T G	More effective in increasing IL-6 production	[26]
IL-1	IL-1α -889	C T	Altered production of IL-1α	[42]
	IL-1α +4845 (exon 5)	G T	Altered production of IL-1α / Increased susceptibility to RA	[34, 38, 41]
	IL-1β -511	C T	Altered production of IL-1RA	[40]
	IL-1β +3953 (exon 5)	C T	Altered production of IL-1RA / Severe joint destruction	[40, 41, 39]
	IL-1RA +2018 (exon2)	C T	Possible pro-inflammatory effect	[43]
IL-6	-174	G C	Reduced production of IL-6	[49]
	-622	G A	Reduced production of IL-6	[48]
IL-10	-1082	G A	Up-regulation of IL-10 production in lymphocytes Lower expression levels of IL-10 / Associated with RA in women	[12] [52, 54]
	-819	T C	Lower expression levels of IL-10 / Autoimmune manifestations	[52, 53]
	-592	A C	Lower expression levels of IL-10 / Autoimmune manifestations	[52, 53]
HLA	Specific shared epitope alleles (HLA-DR)		May increase susceptibility to and severity of RA	[8-10]

TNF-α = tumor necrosis factor-α; TNFRSF 1B = TNFreceptor; IL-1 = interleukin-1; IL-6 = interleukin-6; IL-1RA = IL-1 receptor antagonist; HLA = Human Leukocyte Antigen.