CTLA-4 and MDR1 polymorphisms increase the risk for ulcerative colitis: A meta-analysis

Table 1 Baseline characteristics of all eligible studies

First author	Year	Ethnicity	Genotype method	Number		Gender (M/F)		Gene	SNP
				UC	Control	UC	Control
Brinar et al[29]	2013	Caucasian	PCR-RFLP	52/57		29.9 (26.0-35.70)	-	MDR1	C3435T
Repnik et al[35]	2010	Caucasian	PCR-RFLP	-	119/147	-	37.2	CTLA4	rs3087243 G/A
Ben Alaya et al[17]	2009	Africa	PCR-RFLP	18/47	52/48	39.9 (25-74)	32.4 (24-55)	CTLA4	rs231775 G/A
Farnood et al[30]	2007	Asian	PCR-RFLP	-	-	-	-	MDR1	C3435T
Magyari et al[19]	2007	Caucasian	PCR-RFLP	63/87	49/121	46.1 ± 1.3	57.7 ± 1.3	CTLA4	rs231775 G/A
Lankarani et al[32]	2006	Asian	PCR-RFLP	48/52	48/52	31.6 ± 13.4	35.36 ± 11.94	CTLA4	rs231775 G/A
Wang et al[37]	2006	Asian	PCR-RFLP	41/38	92/72	44.2 ± 16.2	37.8 ± 14.1	CTLA4	rs3087243 G/A
Osuga et al[34]	2006	Asian	PCR-RFLP	37/29	97/76	42.7 ± 14.2	19-76	MDR1	C3435T
Ho et al[31]	2006	Caucasian	PCR-RFLP	-	-	-	-	MDR1	C3435T
Rueda et al[20]	2005	Caucasian	TaqMan	-	-	-	-	CTLA4	rs3087243 G/A
Machida et al[33]	2005	Asian	PCR-RFLP	57/51	125/75	44.0 ± 16.9	32.5 ± 11.1	CTLA4	rs3087243 G/A
Machida et al[33]	2005	Asian	PCR-RFLP	57/51	125/75	44.0 ± 16.9	32.5 ± 11.1	CTLA4	rs231775 G/A
Schwab et al[36]	2003	Caucasian	TaqMan	86/63	86/63	34 ± 11	-	MDR4	C3435T

PB: Population-based; HB: Hospital-based; PCR-RFLP: Polymerase chain reaction restriction fragment length polymorphism; UC: Ulcerative colitis; MDR1: Multi-drug resistance 1; CTLA4: Cytotoxic T lymphocyte-associated antigen-4; SNP: Single nucleotide polymorphisms.

Table 2 Comparisons of genotype and allele frequencies between the case and the control groups

SNP	rs3087243 G/A			rs231775 G/A			rs1045642 C/T
	OR	95%CI	P value	OR	95%CI	P value	OR	95%CI	P value
Allele model
Asians	1.15	0.86-1.55	0.340	1.51	1.15-1.98	0.003	1.47	1.19-1.82	< 0.001
Caucasians	1.56	1.06-2.31	0.026	1.72	1.24-2.39	0.001	1.34	1.13-1.59	0.001
Africas	-	-	-	1.56	0.97-2.49	0.066	-	-	-
Overall	1.37	1.02-1.82	0.035	1.58	1.31-1.92	< 0.001	1.39	1.21-1.59	< 0.001
Dominant model
Asians	1.38	0.96-1.97	0.079	1.90	1.31-2.75	0.001	1.72	1.26-2.36	0.001
Caucasians	1.69	1.29-2.19	< 0.001	1.89	1.21-2.95	0.005	1.35	1.00-1.83	0.048
Africas	-	-	-	1.43	0.76-2.68	0.263	-	-	-
Overall	1.57	1.27-1.94	< 0.001	1.81	1.39-2.34	< 0.001	1.52	1.22-1.89	< 0.001
Homozygous model
Overall	2.41	1.67-3.48	< 0.001	2.21	1.45-3.37	< 0.001	1.92	1.44-2.56	< 0.001
Heterozygous model
Overall	0.62	0.44-0.89	0.008	0.76	0.50-1.15	0.190	0.67	0.53-0.86	0.001
Recessive model
Overall	1.98	1.42-2.76	< 0.001	1.73	1.16-2.57	0.007	1.62	1.29-2.05	< 0.001

OR: Odds ratio.

Table 3 Meta-regression analyses of potential source of heterogeneity

Heterogeneity factors	Coefficient	SE	t	P value	95%CI
				(adjusted)	LL	UL
Year	-0.061	0.035	-1.76	0.359	-0.15	0.028
Country	-0.054	0.03	-1.78	0.352	-0.131	0.024
Ethnicity	0.001	0.042	0.03	1	-0.106	0.109
Method	0.203	0.092	2.2	0.219	-0.034	0.44
SNP	0.045	0.057	0.79	0.85	-0.101	0.191
Sample	0	0	0.09	1	0	0

SE: Standard error; LL: Lower limit; UL: Upper limit. SNP: Single nucleotide polymorphism.