TABLE 1.
Summary characteristics of the studies included in the meta-analysis1
| Age, y | Sample size, n | Sex, % female | Genotyping methods | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Authors | Country | Ethnicity | Study design | Disease | Case | Control | Case | Control | Control source | SNPs | NOS | ||
| de Oliveira et al. (21) | Brazil | Caucasian | Case–control | MCI, AD | 74.60 ± 4.94 | 74.09 ± 7.17 | 15 | 24 | 24 (61.5) | Healthy elderly | PCR | ApaI, BsmI, FokI, TaqI | 7 |
| Keyimu et al. (30) | China | Asian | Case–control | MCI | 65.63 ± 7.46 | 64.44 ± 6.20 | 124 | 124 | 109 (44.0) | Patients who were without MCI, but have the same or similar life background, age, and gender as selected MCI patients | PCR | ApaI, BsmI | 6 |
| Abriz et al. (29) | China | Asian | Case–control | MCI | 77. 22 ± 6.59 | 76. 72 ± 5.71 | 100 | 145 | 127 (51.8) | Patients who were without MCI, but have the same or similar life background, age, and gender as selected MCI patients | PCR | ApaI, BsmI | 6 |
| Gezen-Ak et al. (27) | Turkey | Caucasian | Case–control | AD | 75.1 ± 5.7 | 73.6 ± 7.3 | 104 | 109 | NA | Age-matched controls without any neurodegenerative diseases | PCR | ApaI, BsmI, FokI, TaqI | 4 |
| Gezen-Ak et al. (25) | Turkey | Caucasian | Case–control | AD | 74 ± 4.2 | 75.2 ± 6.8 | 108 | 115 | NA | Controls without any neurodegenerative diseases | PCR | BsmI, FokI | 4 |
| Khorram et al. (24) | Iran | Asian | Case–control | AD | 78.5 ± 7.8 | 77.4 ± 7.0 | 145 | 162 | 190 (61.9) | Age-matched unrelated healthy controls | PCR | ApaI, TaqI | 8 |
| Lehmann et al. (26) | United Kingdom | Caucasian | Case–control | AD | NA | NA | 255 | 260 | 265 (51.5) | Elderly controls from the longitudinal cohort of the Oxford Project to Investigate Memory and Ageing | PCR | ApaI, TaqI | 5 |
| Łaczmański et al. (23) | Poland | Caucasian | Case–control | AD | 73.7 ± 8.6 | 64.5 ± 7.8 | 108 | 77 | 167 (90.3) | Healthy volunteers | PCR | ApaI, BsmI, FokI, TaqI | 6 |
| Luedecking-Zimmer et al. (28) | United States | Caucasian | Case–control | AD | 77.3 ± 6.4 | 76.8 ± 6.3 | 564 | 523 | NA | Controls were obtained from the same geographical area from which the patients were derived, and were found cognitively intact | PCR | FokI | 5 |
| Mun et al. (22) | South Korea | Asian | Case–control | AD | 79.82 ± 7.02 | 68.94 ± 6.10 | 144 | 335 | 285 (59.5) | Healthy elderly | PCR | ApaI, BsmI, FokI, TaqI | 6 |
1
Values are means ± SDs unless otherwise indicated. AD, Alzheimer disease; MCI, mild cognitive impairment; NA, not available; NOS, Newcastle-Ottawa Scale; SNP, single nucleotide polymorphism.