Table 1. Characteristics of the case-control studies included in meta-analysis.
| First authors/references | Year | Country | Ethnicity | Age group | Atopic status | Case(n) | Control(n) | Genotypingmethod | Qualityscore |
| van der Pouw Kraan [7] | 1999 | Netherlands | Caucasian | NA | Atopic | 101 | 107 | PCR-OLA | 5 |
| Hakonarson [8] | 2001 | Iceland | Caucasian | Mixed | Atopic | 94 | 94 | PCR | 10 |
| Howard [9] | 2001 | Holland | Caucasian | Adults | Mixed* | 171 | 119 | Sequencing | 9 |
| Kauppi [10] | 2001 | Finland | Caucasian | NA | NA | 163 | 132 | PCR | 7 |
| Leung [11] | 2001 | China | Asian | Children | Mixed* | 157 | 54 | PCR-RFLP | 9 |
| Xi 1 [12] | 2004 | China | Asian | Adults | NA | 45 | 46 | PCR-RFLP | 5 |
| Xi 2 [12] | 2004 | China | Asian | Children | NA | 43 | 31 | PCR-RFLP | 5 |
| Wu [13] | 2004 | China | Asian | Mixed | NA | 100 | 100 | PCR-RFLP | 7 |
| Donfack 1 [14] | 2005 | USA | Caucasian | NA | Mixed* | 126 | 205 | DNAprint, LAS | 9 |
| Donfack 2 [14] | 2005 | USA | African American | NA | Mixed* | 205 | 183 | DNAprint, LAS | 9 |
| Moissidis [15] | 2005 | USA | African American | Mixed | NA | 61 | 157 | PCR-RFLP | 5 |
| Zhao [16] | 2005 | China | Asian | Children | NA | 130 | 100 | PCR-RFLP | 7 |
| Kabesch [17] | 2006 | Germany | Caucasian | Children | NA | 73 | 773 | PCR-RFLP | 9 |
| Battle [18] | 2007 | USA | African American | Mixed | NA | 264 | 176 | PCR-RFLP | 11 |
| Kang [19] | 2007 | Korea | Asian | Children | NA | 374 | 242 | PCR-RFLP | 11 |
| Chan [20] | 2008 | China | Asian | Children | Mixed | 273 | 141 | PCR-RFLP | 7 |
| Kim [21] | 2008 | Korea | Asian | Children | Mixed* | 715 | 240 | PCR-RFLP | 10 |
| Black [22] | 2009 | UK | Caucasian | Adults | NA | 275 | 2453 | Tetra primer PCR | 11 |
| Daley [23] | 2009 | Australia | Caucasian | Mixed | NA | 644 | 751 | Illumina | 9 |
| Bead Array | |||||||||
| System | |||||||||
| H Li [24] | 2009 | China | Asian | Children | NA | 192 | 192 | PCR-RFLP | 8 |
| Jiang [25] | 2009 | China | Asian | Mixed | NA | 24 | 24 | PCR-RFLP | 7 |
| Llanes [26] | 2009 | Spain | Caucasian | Adults | Atopic | 109 | 50 | PCR-RFLP | 8 |
| Wang [27] | 2009 | China | Asian | Children | Mixed | 446 | 511 | Taqman | 8 |
| Feng [28] | 2009 | China | Asian | Children | NA | 45 | 43 | PCR | 6 |
| Wang [29] | 2009 | China | Asian | Adults | NA | 150 | 160 | PCR-RFLP | 6 |
| Bottema [30] | 2010 | Netherlands | Caucasian | Adults | Atopic | 115 | 92 | MassARRAY | 8 |
| Dmitrieva-Zdorova [31] | 2010 | Russia | Caucasian | Adults | Atopic | 283 | 227 | MALDI-TOF mass-spectrometry | 5 |
| Palikhe [32] | 2010 | Korea | Asian | Adults | NA | 463 | 430 | SNAPshot | 6 |
| Undarmaa 1 [33] | 2010 | Japan | Asian | Children | Atopic | 325 | 336 | TaqMan-ASA | 9 |
| Undarmaa 2 [33] | 2010 | Japan | Asian | Adults | Atopic | 367 | 676 | TaqMan-ASA | 9 |
| Wu XH [34] | 2010 | China | Asian | Children | NA | 252 | 227 | PCR-RFLP | 8 |
| Yang LF [35] | 2010 | China | Asian | Children | NA | 178 | 158 | PCR-RFLP | 5 |
| DeWan [36] | 2010 | USA | Mixed | Children | Atopic | 104 | 503 | Affymetrix | 11 |
| Genome-Wide Human | |||||||||
| SNP Array 5.0, TaqMan | |||||||||
| Yang XX [37] | 2011 | China | Asian | Adults | Mixed* | 193 | 204 | MALDI-TOF mass-spectrometry | 7 |
| Baye 1 [38] | 2011 | USA | Caucasian | Children | NA | 413 | 298 | IGGAS | 9 |
| Baye 2 [38] | 2011 | USA | African American | Children | NA | 315 | 51 | IGGAS | 9 |
| Noguchi [39] | 2011 | Japan | Asian | Children | Mixed | 938 | 2376 | Illumina HumanHap550v3 | 12 |
| /610-Quad Genotyping BeadChip | |||||||||
| Munoz [40] | 2012 | Mexico | Caucasian | Children | NA | 90 | 111 | TaqMan | 5 |
*
Data for atopic or non-atopic asthma patients could be separately extracted.
PCR, polymerase chain reaction; OLA, oligonucleotide ligase assay; RFLP, restriction fragment length polymorphism; LAS, multiplex PCR and an immobilized linear array system; TaqMan-ASA, TaqMan allele-specific amplification method; IGGAS, Illumina GoldenGate Assay system; NA, not available.