Table 1 Characteristics of studies included in the meta-analysis

Baris S(2016)

Turkish

37.8 ± 1.0

–

PCR-RFLP

rs1800896

–

Hu J. stage I(2015)

Chinese Han

33.60 ± 8.78

39.66 ± 11.19

PCR-RFLP

rs1800896, rs1800872, rs1554286

p > 0.05

Hu J. stage II(2015)

Chinese Han

33.60 ± 8.78

39.66 ± 11.19

PCR-RFLP

rs1800871

p > 0.05

Al-Okaily F(2015)

Saudi

37.87 ± 12.5

36 ± 10

PCR-ARMS

rs1800896, rs1800871, rs1800872

–

Talaat R. M(2014)

Egyptian

34.37 ± 10.36

–

PCR-SSP

rs1800896, rs1800871

p > 0.05

Xavier J. M(2012)

Iranian

39.1 ± 11.0

42.0 ± 11.6

Sequenom iPlex assay

rs1800896, rs1518111, rs1554286

P > 0.01

Shahram F(2011)

Iranian

–

–

PCR-SSP

rs1800896, rs1800871, rs1800872

p > 0.05

Ates O(2010)

Turkish

37.2 ± 8.4

52 ± 7

PCR-ARMS

rs1800896, rs1800871, rs1800872

–

Dilek K(2009)

Turkish

–

–

PCR-SSP

rs1800896, rs1800871, rs1800872

p > 0.05

Wallace GR(2007)

UK

–

–

PCR-SSP

rs1800896, rs1800871

p > 0.05

Wallace GR(2007)

ME

–

–

PCR-SSP

rs1800896, rs1800871

p > 0.05

Kramer M(2018)

Turkish

–

–

Sanger technique

rs1800871, rs1800872, rs1518111

–

Kramer M(2018)

Israeli

–

–

Sanger technique

rs1800871, rs1800872, rs1518111

–

Yu H(2017)

Chinese Han

34.86 ± 9.9

35.46 ± 10.3

Sequenom Mass Array

rs1800871, rs1554286

–

Carapito R(2015)

Iranian

–

–

Taqman

rs1800871, rs1518111

–

Wu Z(2014)

Chinese

38.02 ± 12.44

38.81 ± 10.45

Sequenom Mass Array

rs1800871, rs1518111

p > 0.05

Khaib Dit Naib O(2013)

Western Algeria

26 ± 11

–

Direct sequencing

rs1800871, rs1800872

–

Kirino Y(2013)

Turkish

–

–

GWAS

rs1800871, rs1518111

P < 0.0001

Mizuki N(2010)

Japanese

–

–

GWAS

rs1800871, rs1800872

P < 0.001

Mizuki N(2010)

Korean

–

–

GWAS

rs1800871, rs1800872

P < 0.001

Mizuki N(2010)

Turkish

–

–

GWAS

rs1800871, rs1800872

P < 0.001

Afkari B(2018)

Iranian

38.02 ± 10.25

37.4 ± 8.5

PCR-RFLP

rs1800872

p > 0.05

Montes-Cano MA(2013)

Spanish

38.7 ± 13.8

–

Taqman

rs1800872

p > 0.05

Remmers EF(2010)

Discovery-Turkish

–

–

GWAS

rs1518111

p > 0.00001

Remmers EF(2010)

Rplication-Turkish

–

–

GWAS

rs1518111

p > 0.00001

Remmers EF(2010)

Replication-Middle Eastern Arab

–

–

GWAS

rs1518111

p > 0.00001

Remmers EF(2010)

Replication-Greek

–

–

GWAS

rs1518111

p > 0.00001

Remmers EF(2010)

Replication-UK Caucasian

–

–

GWAS

rs1518111

p > 0.00001

Remmers EF(2010)

Replication-Korean

–

–

GWAS

rs1518111

p > 0.00001

Remmers EF(2010)

Replication-Japanese

–

–

GWAS

rs1518111

p > 0.00001