Interleukin-18 genetic polymorphisms contribute differentially to the susceptibility to Crohn’s disease

Table 1 Main characteristics and methodological quality of all eligible studies of the relationship between interleukin-18 genetic polymorphisms and the risk of developing Crohn’s disease

Ref.	Year	Country	Ethnicity	Number		Gender (M/F)		Age (yr)		Genotyping method	SNP type	HWE test (Pvalue)	NOS score
				CD	Control	CD	Control	CD	Control
Ben Aleya et al[21]	2011	Tunisia	African	105	100	50/55	52/48	23-60	-	PCR-SSP	rs1946518 A>C	0.051	6
											rs187238 G>C	0.284
Dema et al[27]	2009	Spain	Caucasian	722	794	274/448	-	-	-	TaqMan	rs917997 C>T	0.609	5
Haas et al[29]	2005	Germany	Caucasian	470	347	139/331	122/225	-	-	TaqMan	rs187238 G>C	0.637	6
Glas et al[28]	2005	Germany	Caucasian	210	265	83/127	141/124	39.1 ± 13.6	43.2 ± 12.5	PCR-RFLP	rs1946518 A>C	0.592	8
											rs187238 G>C	0.123
											codon 35 A>C	0.774
Tamura et al[31]	2008	Japan	Asian	134	110	102/32	55/55	15-65	15-75	Direct sequencing	codon 35 A>C	0.606	8
Takagawa et al[30]	2005	Japan	Asian	210	212	150/60	97/115	32.4 ± 9.8	38.2 ± 13.7	PCR-SSP	rs1946518 A>C	0.298	8
											rs187238 G>C	0.197
Aizawa et al[26]	2005	Japan	Asian	79	102	61/18	50/52	36.8 ± 9.2	37.6 ± 6.9	Direct sequencing	rs1946519 G>T	0.947	8
											rs1946518 A>C	0.840
											rs187238 G>C	0.586
											rs360718 A> C	0.327

M/F: Male/female; CD: Crohn’s disease; SNP: Single nucleotide polymorphism; HWE: Hardy-Weinberg Equilibrium; NOS: Newcastle-Ottawa Scale; PCR-SSP: Polymerase chain reaction-sequence-specific primers; RFLP: Restriction fragment length polymorphism.