Table 1 General characteristics of studies included in the meta-analysis
AuthorYearCountryMethods of genotypeSample sizeGene frequency (Case)Gene frequency (Control)HWEScore of quality
CaseControlPPPAAAPPPAAA
Ostgren [22]2003SwedenPCR-RFLP1941901474341365130.4688
Rodriguez-Esparragon [23]2003SpainPCR2292122062211743620.9287
Horiki [7]2004JapanPCR-RFLP2053001931202762400.4717
Shen [24]2004ChinaPCR-RFLP125112113111103900.6587
Shen [12]2004ChinaPCR-RFLP7022066312061310.1286
Zhang [25]2005ChinaPCR-RFLP13215712840148900.7127
Gouni-Berthold [8]2005GermanPCR-RFLP2551401905781043240.4307
Pan [26]2007ChinaPCR-RFLP1771191542301011800.3727
Hui [27]2007JpanTaqMan PCR2612712151602611000.7577
Lu [28]2008ChinaPCR-RFLP4783614463113124810.5507
Ruixing [13]2008ChinaPCR-RFLP4461213418235124764120.0007
Gao [14]2010ChinaPCR-RFLP34513733771131240.0007
Zhang [15]2011ChinaPCR-SSCP*2804102641603921800.6507
Dong [9]2012ChinaPCR-RFLP12417812220177100.9707
Lian [16]2012ChinaTaqMan PCR2725481669016293205500.1087
Bener [10]2013KatarPCR22013081852871175122110.0008
Gu [29]2013ChinaTaqMan PCR2695511668518293210480.2627
Chen [30]2014ChinaMALDI-TOF-MS1451651103321055370.9246
Wang [31]2015ChinaPCR-RFLP81682453624436426318800.0717
Grygiel-Gorniak [17]2015PolandTaqMan PCR151120101446843240.6617
Zhang [18]2018ChinaPCR-RFLP3092902624522593100.3368
  • *PCR-SSCP, Polymerase chain reaction single-strand conformation polymorphism.