Table 1. Characteristics of eligible studies in the meta-analysis of MTHFR 677C>T polymorphism and male infertility.
| Cases | Controls | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| First author | Year | Quality scores | Group | Design | Total | CC | CT | TT | Total | CC | CT | TT | P HWE |
| Asians | |||||||||||||
| Park | 2005 | 6 | Total | HB | 373 | 105 | 205 | 63 | 396 | 145 | 200 | 51 | 0.161 |
| Azoo | 286 | 75 | 164 | 47 | |||||||||
| OAT | 85 | 28 | 40 | 17 | |||||||||
| Lee | 2006 | 6 | Total | HB | 360 | 115 | 181 | 64 | 325 | 118 | 166 | 41 | 0.138 |
| Azoo | 174 | 44 | 100 | 30 | |||||||||
| OAT | 186 | 71 | 81 | 34 | |||||||||
| A | 2007 | 6 | Total | NA | 355 | 130 | 160 | 65 | 252 | 128 | 95 | 29 | 0.085 |
| Azoo | 228 | 83 | 97 | 48 | |||||||||
| oligo | 127 | 47 | 63 | 17 | |||||||||
| Sun | 2007 | 5 | Total | PB | 182 | 27 | 86 | 69 | 53 | 15 | 28 | 10 | 0.630 |
| OAT | 22 | 3 | 11 | 8 | |||||||||
| oligo | 46 | 10 | 20 | 16 | |||||||||
| Yang | 2010 | 5 | Total | PB | 131 | 34 | 55 | 42 | 293 | 98 | 142 | 53 | 0.901 |
| Qiu | 2011 | 6 | Total | NA | 271 | 75 | 112 | 84 | 180 | 63 | 85 | 32 | 0.720 |
| Azoo | 158 | 42 | 66 | 50 | |||||||||
| oligo | 113 | 33 | 46 | 34 | |||||||||
| Safarinejad | 2011 | 6 | OAT | HB | 164 | 58 | 80 | 26 | 328 | 144 | 148 | 36 | 0.825 |
| Liu | 2012 | 7 | Total | PB | 75 | 27 | 38 | 10 | 72 | 40 | 28 | 4 | 0.753 |
| Pei | 2013 | 7 | Total | PB | 290 | 39 | 138 | 113 | 90 | 24 | 47 | 19 | 0.651 |
| Li | 2014 | 6 | Total | HB | 82 | 14 | 36 | 32 | 133 | 36 | 61 | 36 | 0.340 |
| Caucasians | |||||||||||||
| Ebisch | 2003 | 7 | Total | PB | 77 | 42 | 28 | 7 | 113 | 50 | 48 | 15 | 0.522 |
| Stuppia | 2003 | 5 | Total | NA | 93 | 37 | 37 | 19 | 105 | 33 | 43 | 29 | 0.065 |
| Azoo | 21 | 8 | 6 | 7 | |||||||||
| oligo | 66 | 25 | 29 | 12 | |||||||||
| Singh | 2005 | 6 | Total | PB | 151 | 105 | 40 | 6 | 200 | 163 | 37 | 0 | 0.149 |
| Paracchini | 2006 | 6 | Total | PB | 59 | 11 | 32 | 16 | 46 | 18 | 21 | 7 | 0.830 |
| Ravel | 2009 | 6 | Total | HB | 250 | 118 | 101 | 31 | 114 | 49 | 52 | 13 | 0.887 |
| Azoo | 70 | 33 | 31 | 6 | |||||||||
| oligo | 180 | 85 | 70 | 25 | |||||||||
| Murphy | 2011 | 7 | Total | PB | 149 | 73 | 63 | 13 | 182 | 94 | 73 | 15 | 0.876 |
| Gupta | 2011 | 5 | Total | HB | 522 | 378 | 116 | 28 | 315 | 251 | 58 | 6 | 0.228 |
| Azoo | 68 | 49 | 15 | 4 | |||||||||
| OAT | 65 | 41 | 23 | 1 | |||||||||
| Chellat | 2012 | 5 | Total | NA | 74 | 31 | 33 | 10 | 84 | 36 | 38 | 10 | 0.995 |
| Azoo | 46 | 20 | 19 | 7 | |||||||||
| OAT | 28 | 11 | 14 | 3 | |||||||||
| Weiner | 2013 | 6 | Total | PB | 271 | 129 | 116 | 26 | 301 | 153 | 115 | 33 | 0.112 |
| Azoo | 98 | 49 | 41 | 8 | |||||||||
| oligo | 82 | 40 | 31 | 11 | |||||||||
| Naqvi | 2014 | 5 | Total | NA | 637 | 447 | 154 | 36 | 364 | 275 | 79 | 10 | 0.145 |
| Azoo | 49 | 34 | 11 | 4 | |||||||||
| OAT | 65 | 39 | 24 | 2 | |||||||||
| oligo | 37 | 23 | 12 | 2 | |||||||||
| Mfady | 2014 | 6 | Total | HB | 150 | 67 | 63 | 20 | 150 | 74 | 67 | 9 | 0.221 |
| Africans | |||||||||||||
| Eloualid | 2012 | 5 | Total | NA | 257 | 152 | 88 | 17 | 690 | 351 | 286 | 53 | 0.617 |
| Azoo | 110 | 65 | 37 | 8 | |||||||||
| oligo | 147 | 87 | 51 | 9 | |||||||||
| Not mentioned | |||||||||||||
| Gava (37) | 2011 | 7 | Total | PB | 156 | 81 | 60 | 15 | 233 | 167 | 53 | 13 | 0.003 |
| Azoo | 49 | 27 | 15 | 7 | |||||||||
| oligo | 107 | 54 | 45 | 8 | |||||||||
| Gava (49) | 2011 | 7 | Total | PB | 133 | 66 | 51 | 16 | 173 | 136 | 27 | 10 | 0.000 |
| Azoo | 55 | 35 | 14 | 6 | |||||||||
| oligo | 78 | 31 | 37 | 10 | |||||||||
| Vani | 2012 | 6 | Total | HB | 206 | 158 | 42 | 6 | 230 | 188 | 42 | 0 | 0.128 |
| Camprubí | 2013 | 6 | Total | PB | 107 | 47 | 43 | 17 | 25 | 8 | 15 | 2 | 0.172 |
| oligo | 23 | 12 | 9 | 2 |
Azoo-azoospermia; OAT-oligoasthenoteratozoospermia; oligo-oligozoospermia
HB, hospital-based controls; PB, population-based controls
HWE, Hardy Weinberg Equilibrium
NA, not available