Table 1.
Key methodological characteristics of included studies
| Author | Year of publication | Design | Study cohort | Country | Ethnicity | Sample size (case/control) | Genotypes distribution (case/control) | Allelic distribution (case/control) | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| CC | TC | TT | T | C | |||||||
| Hamza et al16 | 2011 | Case‐control | NGRC | United States | Caucasian | 1458/931 | 1227/716 | 219/204 | 12/11 | 216/200 | 2700/1662 |
| PEG | United States | Caucasian | 280/310 | 234/249 | 42/55 | 4/6 | 46/60 | 514/560 | |||
| PAGE | United States | Caucasian | 525/1474 | 434/1199 | 85/267 | 6/8 | 88/258 | 962/2690 | |||
| HIHG | United States | Caucasian | 209/133 | 169/110 | 36/22 | 4/1 | 39/22 | 379/244 | |||
| Yamada‐Fowler et al17 | 2014 | Case‐control | Swedish population | Sweden | Caucasian | 193/377 | 159/284 | 30/88 | 4/5 | 38/98 | 348/656 |
| Ahmed et al18 | 2014 | Case‐control | French population | France | Caucasian | 300/598 | 242/492 | 56/101 | 2/5 | NA | NA |
| Danish population | Denmark | Caucasian | 1288/1394 | 1042/1094 | 232/286 | 14/14 | NA | NA | |||
| Seattle population | United States | Caucasian | 386/502 | 302/418 | 77/81 | 7/3 | NA | NA | |||
| Rochester population | United States | Caucasian | 315/315 | 247/244 | 68/68 | 0/3 | NA | NA | |||
| Kim et al19 | 2018 | Case‐control | HPFS | United States | Caucasian | 286/964 | 242/809 | 43/146 | 1/9 | 45/164 | 527/1764 |
| NHS | United States | Caucasian | 393/1625 | 301/1291 | 90/320 | 2/14 | 94/348 | 692/2902 | |||
| CPS‐IIN | United States | Caucasian | 150/165 | 114/130 | 36/35 | 0/0 | 36/35 | 264/295 | |||
Abbreviations: CPS‐IIN, Cancer Prevention Study II Nutrition Survey; HIHG, Hussman Institute for Human Genomics; HPFS, Health Professionals Follow‐up Study; NA, Not available; NGRC, NeuroGenetics Research Consortium; NHS, Nurses’ Health Study; PAGE, Parkinson's, Genes, and Environment from the prospective NIH‐AARP Diet and Health Study; PEG, Parkinson, Environment and Gene.