Table 2.

Studies included in the meta-analysis

No.	First author	Year	Population	Number of participants used in analysis
				CD	UC	Controls
1	Hampe et al[5]1	2007	Germany, UK	2122	1227	2056, 1032 for CD, UC respectively
2	Baldassano et al[6]	2007	USA	142	NA	281
3	Büning et al[7]	2007	Germany, Hungary, Netherlands	614	296	707
4	Cummings et al[8]	2007	UK	645	676	1190
5	Prescott et al[9]	2007	UK	727	877	579
6	Rioux et al[10]2	2007	North-America	1571	353	1184, 207 for CD, UC respectively
7	Roberts et al[11]	2007	New Zealand	496	466	549
8	Yamazaki et al[12]	2007	Japan	481	NA	437
9	Amre et al[13]	2009	Canada	286	NA	290
10	Baptista et al[14]	2008	Brazil	180	NA	189
11	Fowler et al[15]3	2008	Australia	154	NA	420
12	Gaj et al[16]	2008	Poland	59	NA	140
13	Glas et al[17]	2008	Germany	768	507	1615
14	Lakatos et al[18]	2008	Hungary	266	149	149
15	Lappalainen et al[19]	2008	Finland	240	459	190
16	Latiano et al[20]	2008	Italy	667	668	749
17	Okazaki et al[21]	2008	Canada	208	113	314
18	Perricone et al[22]	2008	Italy	163	NA	160
19	Peterson et al[23]	2008	USA	555	NA	486
20	Van Limbergen et al[24]4	2008	Scotland	629	580	345
21	Zhi et al[25]	2008	China	40	40	50
22	Weersma et al[26]	2009	Holland	1684	1120	1350
23	Hancock et al[27]	2008	UK	586	NA	1156
24	Yang et al[28]	2009	Korea	377	NA	372
25	Newman et al[29]	2009	Canada	435	NE	895
Total				14 095	7531	15 849, 13 852 for CD, UC respectively

¹Data were extracted from the combination of panel A, panel B, panel C, and UC cohort; ²Only GWA study and replication cohort 2 study were included; ³Data from the cohort 1 study were not included in the analysis based on the use of data for controls from 251 families with IBD; ⁴Data of the UC group were obtained by communication with the authors of this publication. CD: Crohn’s disease; UC: Ulcerative colitis; NA: Not applicable (no such group); NE: Non-extractable or unavailable data.