Table 13 Studies examining enzymes of the γ-glutamyl cycle or transulphuration pathway in autism

Glutathione peroxidase

Plasma

Yorbik et a l. 2002 [71]

45 cases, (39 M, 6 F) 41 controls, (35 M, 6 F)

270 ± 40

390 ± 80

< 0.05

low

U/L

Söğüt et al. 2003 [72]

27 cases, (16 M, 11 F) 30 controls, (16 M, 14 F)

40.9 ± 11.3

24.2 ± 6.3

< 0.0001

high

U/L

Al-Gadani et al. 2009 [81]

30 cases, (22 M, 8 F) 30 controls, (20 M, 10 F)

2468.8 ± 999.3

1438.5 ± 611.2

< 0.05

high

U/L

Mostafa et al. 2010 [83]

44 cases, (30 M,14 F) 44 controls, (30 M, 14 F)

441.5 (100)²

589 (176)²

< 0.001

low

U/L

Erythrocytes

Golse et al. 1978 [63]

24 cases, (17 M, 7 F)

6 controls, (2 M, 4 F)

4.7 ± 0.29

8.45 ± 0.95

< 0.0001

low

U/g haemoglobin

Yorbik et al. 2002 [71]

45 cases, (39 M, 6 F) 41 controls, (35 M, 6 F)

28.72 ± 2.64

38.01 ± 5.03

< 0.05

low

U/g haemoglobin

Pasca et al. 2006 [74]

12 cases, (9 M, 3 F)

9 controls, (6 M, 3 F)

7.75 ± 0.93

7.45 ± 0.65

ns

ns

U/g haemoglobin

Vergani et al. 2011 [84]

28 cases (21 M, 7 F)

32 controls (20 M, 12 F)

ns

ns

nmols NADPH/min/mg haemoglobin

Platelets

Golse et al. 1978 [63]

36 cases, (15 M, 21 F) 21 controls, (9 M, 12 F)

51.53 ± 1.61

46.56 ± 2.69

ns

ns

U/g platelet protein

Glutathione reductase

Plasma

Al-Yafee et al. 2011 [85]

20 cases (20 M, 0 F)

20 controls (20 M, 0 F)

70.25 ± 16.35

60.19 ± 15.42

0.052

trend high

U/L

Glutathione-s-transferase

Plasma

Al-Yafee et al. 2011 [85]

20 cases (20 M, 0 F)

20 controls (20 M, 0 F)

0.42 ± 0.18

0.73 ± 0.37

0.002

low

μmol/min/ml