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

Table 2 Meta-analysis of subgroups for the relationships between IL-18 genetic polymorphisms and Crohn’s disease risk

	W allele vs M allele (Allele model)			WW + WM vs MM (Dominant model)			WW vs WM + MM (Recessive model)			WW vs MM (Homozygous model)			WW vs WM (Heterozygous model)
	OR	95%CI	Pvalue	OR	95%CI	Pvalue	OR	95%CI	Pvalue	OR	95%CI	Pvalue	OR	95%CI	Pvalue
SNP type
rs1946518 A>C	1.45	1.22-1.72	0.000	1.62	1.22-2.14	0.001	1.59	1.26-2.01	0.000	1.98	1.45-2.72	0.000	1.43	1.12-1.84	0.005
rs187238 G>C	1.69	1.39-2.06	0.000	2.04	1.48-2.81	0.000	1.81	1.42-2.31	0.000	2.53	1.82-3.52	0.000	1.66	1.29-2.13	0.000
rs360718 A>C	2.03	1.20-3.43	0.008	2.33	0.46-11.88	0.308	2.39	1.29-4.43	0.006	3.17	0.61-16.40	0.169	2.31	1.22-4.38	0.010
rs917997 C>T	0.91	0.77-1.06	0.229	0.80	0.55-1.18	0.267	0.91	0.74-1.11	0.349	0.78	0.52-1.16	0.220	0.93	0.76-1.15	0.525
codon 35 A>C	1.15	0.91-1.45	0.256	1.30	0.75-2.26	0.355	1.15	0.85-1.55	0.360	1.41	0.79-2.52	0.250	1.11	0.81-1.52	0.523
rs1946519 G>T	1.14	0.74-1.77	0.545	1.24	0.51-3.03	0.641	1.17	0.64-2.13	0.604	1.32	0.51-3.43	0.566	1.13	0.60-2.13	0.697
Ethnicity
Asians	1.54	1.28-1.85	0.000	1.81	1.29-2.53	0.001	1.65	1.28-2.12	0.000	2.25	1.56-3.24	0.000	1.54	1.18-2.00	0.001
Africans	1.99	1.42-2.79	0.000	2.69	1.55-4.67	0.000	2.11	1.38-3.22	0.001	3.55	1.67-7.53	0.001	1.66	1.07-2.59	0.025
Caucasians	1.23	0.97-1.54	0.083	1.27	0.92-1.77	0.148	1.29	0.97-1.73	0.079	1.44	0.94-2.22	0.096	1.25	0.97-1.61	0.086
Genotyping method
PCR-SSP	1.67	1.35-2.07	0.000	1.91	1.37-2.67	0.000	1.84	1.45-2.34	0.000	2.35	1.55-3.56	0.000	1.67	1.30-2.15	0.000
TaqMan	1.20	0.69-2.10	0.521	1.17	0.55-2.53	0.681	1.29	0.64-2.58	0.479	1.32	0.46-3.80	0.603	1.27	0.68-2.36	0.450
PCR-RFLP	1.25	1.07-1.46	0.005	1.36	1.00-1.85	0.053	1.31	1.06-1.63	0.013	1.55	1.11-2.16	0.011	1.25	0.99-1.56	0.059
Direct sequencing	1.56	1.16-2.11	0.003	2.46	1.37-4.43	0.003	1.61	1.08-2.42	0.021	3.21	1.72-5.99	0.000	1.46	0.98-2.18	0.061
Sample size
Small sample-size (n ≤ 200)	1.61	1.29-2.01	0.000	2.29	1.60-3.27	0.000	1.66	1.25-2.20	0.001	2.85	1.93-4.20	0.000	1.46	1.12-1.90	0.005
Large sample-size (n > 200)	1.33	1.08-1.63	0.007	1.33	1.02-1.74	0.038	1.44	1.11-1.86	0.007	1.54	1.07-2.21	0.019	1.38	1.08-1.76	0.009

W: Wild-type allele; M: Mutant allele; WW: Wild-type homozygote; WM: Heterozygote; MM: Mutant homozygote; OR: Odds ratio; SNP: Single nucleotide polymorphism.