Table 2: Risk of bias assessment.

Author, yearAscertainment of GRAscertainment of non-GRGenotyping controlsPopulation stratificationConfounding biasSelective outcome reportsHWE

Azzawi et al. 2001 [11]YesYesUnclearNANoYesNo
Bijlsma et al. 2002 [6]YesYesYesNANoYesNo
Plaza et al. 2003 [10]YesYesYesNANoYesYes
Gourley et al. 2004 [8]YesYesYesUnclearNoYesNo
McDaniel et al. 2004 [9]YesYesYesUnclearNoYesNo
Filippo et al. 2006 [7]YesYesYesUnclearNoYesNo
Girnita et al. 2008 [12]YesYesNAYesYesYesNo

NA: not available.