Table 2.

Assessment of potential bias in included studies

Year	First author	Bias in selection of cases	Bias in selection of controls	Bias in genotyping controls	Bias in population stratification	Confounding bias	Multiple test and Selective outcome reports
2007	Yate et al. [54]	NO	NO	NO	NO	NO	NO
2007	Maller et al. [41]	NO	NO	NO	NO	NO	NO
2008	Edwards et al. [31]	NO	NO	NO	NO	NO	NO
2008	Spencer et al. [50]	NO	NO	NO	NO	NO	NO
2009	Scholl et al. [4]	NO	NO	NO	NO	NO	NO
2009	Francis et al. [32]	NO	NO	NO	NO	NO	NO
2009	Park et al. [44]	NO	NO	NO	NO	NO	NO
2009	Despriet et al. [30]	NO	NO	NO	NO	NO	NO
2009	Bergeron et al. [22]	NO	NO	NO	NO	NO	NO
2009	Reynolds et al. [47]	NO	NO	NO	NO	NO	NO
2009	Pei et al. [45]	NO	NO	NO	NO	NO	NO
2010	Cui et al. [29]	NO	NO	NO	NO	NO	NO
2010	Zerbib et al. [56]	NO	NO	NO	NO	NO	NO
2010	McKay et al. [43]	NO	NO	NO	NO	NO	NO
2010	Chen et al. [25]	NO	NO	NO	NO	NO	NO
2010	Kopplin et al. [37]	NO	NO	NO	Unclear	NO	NO
2010	Liu et al. [39]	NO	NO	NO	NO	NO	NO
2011	Yu et al. [55]	NO	NO	NO	NO	NO	NO
2011	Chen et al. [26]	NO	NO	NO	NO	NO	NO
2011	Hageman et al. [33]	NO	NO	NO	Unclear	NO	NO
2011	Peter et al. [46]	Yes	NO	NO	Unclear	NO	NO
2011	Yanagisawa et al. [53]	NO	NO	NO	NO	NO	NO
2012	Martinez et al. [42]	NO	NO	NO	NO	NO	NO
2012	Smailhodzic et al. [49]	NO	NO	NO	NO	NO	NO
2012	Buentello et al. [23]	NO	NO	NO	NO	NO	NO
2012	Tian et al. [51]	NO	NO	NO	NO	NO	NO
2012	Losonczy et al. [40]	NO	NO	NO	NO	NO	NO
2012	Cipriani et al. [27]	NO	Yes	NO	NO	NO	NO
2012	Jaouni et al. [36]	NO	NO	NO	NO	NO	NO
2013	Wu et al. [52]	NO	NO	NO	NO	NO	NO
2013	Helgason et al. [35]	NO	NO	NO	NO	NO	NO
2014	Contreras et al. [28]	NO	NO	NO	NO	NO	NO
2014	Caire et al. [24]	NO	NO	NO	NO	NO	NO
2014	Liu et al. [38]	NO	NO	NO	NO	NO	NO
2015	Hautamaki et al. [34]	NO	NO	NO	NO	NO	NO
2016	Saksens et al. [48]	NO	NO	NO	NO	NO	NO
2017	Bonyadi et al. [20, 21]	NO	NO	NO	NO	NO	NO
2017	Habibi et al. [57]	NO	NO	NO	NO	NO	NO