Table 1.
General characteristics of studies included in the current meta-analysis
| Author | Year | Country | Ethnicity | Sample type | Case, N (M, %) | Control, N (M, %) |
|---|---|---|---|---|---|---|
| Kwong et al17 | 2002 | People’s Republic of China | Asian | Tissue | 33 (72.72%) | 6 (0.00%) |
| Liang et al39 | 2015 | People’s Republic of China | Asian | Tissue | 48 (75.00%) | 26 (0.00%) |
| Wonget al40 | 2002 | People’s Republic of China | Asian | Tissue | 32 (75.00%) | 5 (0.00%) |
| Zhang et al36 | 2012 | People’s Republic of China | Asian | Tissue | 49 (67.35%) | 20 (0.00%) |
| Nawaz et al27 | 2015 | Morocco | Caucasian | Tissue | 44 (25.00%) | 18 (27.78%) |
| Kong et al38 | 2006 | People’s Republic of China | Asian | Tissue | 46 (76.00%) | 6 (0.00%) |
| Fendri et al26 | 2009 | Tunisia | Caucasian | Tissue | 68 (88.24%) | 9 (0.00%) |
| Challouf et al37 | 2012 | Tunisia | Caucasian | Tissue | 36 (47.22%) | 19 (15.79%) |
| Chang et al35 | 2003 | People’s Republic of China | Asian | Tissue | 30 (76.67%) | 6 (0.00%) |
| Tong et al34 | 2002 | People’s Republic of China | Asian | Brushing | 28 (50.00%) | 12 (0.00%) |
| Yang et al33 | 2015 | People’s Republic of China | Asian | Brushing | 96 (68.75%) | 43 (18.60%) |
| Chang et al35 | 2003 | People’s Republic of China | Asian | Brushing | 30 (50.00%) | 43 (2.33%) |
| Zhang et al36 | 2012 | People’s Republic of China | Asian | Brushing | 49 (55.10%) | 20 (0.00%) |
| Chang et al35 | 2003 | People’s Republic of China | Asian | Brushing | 30 (63.33%) | 37 (0.00%) |
| Yang et al33 | 2015 | People’s Republic of China | Asian | Blood | 220 (27.27%) | 50 (4.00%) |
| Wong et al32 | 2004 | People’s Republic of China | Asian | Blood | 41 (19.51%) | 43 (0.00%) |
| Tian et al31 | 2013 | People’s Republic of China | Asian | Blood | 35 (51.43%) | 41 (9.76%) |
Abbreviation: M, Methylation.