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Table 1 Characteristics of included studies for MTHFR C677T polymorphism

From: Association between MTHFR C677T/A1298C and susceptibility to autism spectrum disorders: a meta-analysis

Author, year Quality Score Country Ethnicity Case Control Sample source Folate HWE
N CC CT TT N CC CT TT    
Boris et al. 2004 [22] 6 USA Caucasian 168 35 94 39 5389 2570 2213 606 Hospital-based YES 0
James et al. 2006 [43] 7 USA Caucasian 356 134 176 46 205 93 90 22 Hospital-based YES 0.974
Mohammad et al. 2009 [35] 7 USA Asian 138 98 35 5 138 120 18 0 Population-based NO 0.412
Pasca et al. 2009 [27] 8 Romania Caucasian 39 21 14 4 80 46 28 6 Population-based NO 0.551
dos Santos et al. 2010 [28] 7 Brazil Caucasian 151 60 68 23 100 45 41 14 Hospital-based YES 0.353
Liu et al. 2011 [44] 7 Canada Caucasian 205 68 98 39 384 177 166 41 Population-based YES 0.823
Liu et al. 2011 [44] 7 Canada Caucasian 400 167 179 54 384 177 166 41 Population-based YES 0.823
Schmidt et al. 2011 [45] 8 USA Caucasian 294 128 133 33 180 74 77 29 Population-based YES 0.241
Guo et al. 2012 [31] 7 China Asian 186 79 77 30 186 87 83 16 Population-based NO 0.542
Divyakolu et al. 2013 [46] 6 India Asian 50 27 22 1 50 42 8 0 Hospital-based NO 0.539
Park et al. 2014 [47] 7 Korea Asian 249 76 136 37 423 139 204 80 Hospital-based NO 0.737
Sener et al. 2014 [48] 9 Turkey Caucasian 98 44 51 3 70 37 33 0 Population-based NO 0.009
Shawky et al. 2014 [46] 6 Egypt Caucasian 20 7 10 3 22 16 6 0 Hospital-based NO 0.459
Meguid et al. 2015 [49] 8 Egypt Caucasian 24 11 11 2 30 20 8 2 Population-based NO 0.361
El-baz et al. 2017 [32] 6 Egypt Caucasian 31 12 15 4 39 35 4 0 Hospital-based YES 0.735
Zhao et al. 2013 [36] 9 China Asian 200 91 59 50 200 144 39 17 Hospital-based NO 0