Table 2 Association between the 50 bp Ins/Del genetic polymorphism at promoter region of the SOD1 and risk of heroin dependence

Ins/Ins

590 (73.8)

328 (74.2)

1.0

-

-

1.0^a

-

-

Ins/Del

188 (23.5)

102 (23.1)

0.97

0.74–1.28

0.863

0.96

0.73–1.28

0.827

Del/ Del

21 (2.6)

12 (2.7)

1.02

0.49–2.11

0.941

1.01

0.49–2.09

0.969

Ins/Ins

486 (73.4)

297 (74.3)

1.0

-

-

1.0^b

-

-

Ins/Del

159 (24.0)

91 (22.7)

0.93

0.69–1.25

0.663

0.94

0.70–1.26

0.660

Del/ Del

17 (2.6)

12 (3.0)

1.15

0.54–2.45

0.707

1.16

0.55–2.46

0.702

Ins/Ins

104 (75.9)

31 (73.8)

1.0

-

-

1.0^b

-

-

Ins/Del

29 (21.2)

11 (26.2)

1.23

0.57–2.83

0.556

1.27

0.57–2.83

0.559

Del/ Del

4 (2.9)

- (0.0)

-

-

-

-

-

-