Table 4 Analysis of gene-gene interactions (all cases versus controls) after adjustment*
Gene-gene interactionsMultiplicative interactionp Value
Odds ratio (95% CI)
CYP2D6GSTM10.68 (0.30 to 1.56)0.37
PON55GSTM10.80 (0.48 to 1.34)0.40
PON192GSTM10.88 (0.64 to 1.22)0.45
GSTT1GSTM11.17 (0.76 to 1.80)0.47
GSTM3GSTM10.75 (0.52 to 1.09)0.13
GSTP1 haplotypeGSTM10.88 (0.62 to 1.24)
    AB/AC/AD vs AANull vs pos1.23 (0.69 to 2.19)0.48**
    BB/BC/CC vs AANull vs pos
NQO1GSTM10.96 (0.70 to 1.35)0.82
NAT2GSTM11.17 (0.67 to 2.04)0.58
CYP2D6GSTT11.21 (0.36 to 4.10)0.76
GSTP1 haplotypeGSTT11.11 (0.70 to 1.74)
    AB/AC/AD vs AANull vs pos1.38 (0.63 to 3.01)0.70**
    BB/BC/CC vs AANull vs pos
MAO-B (males only)NQO10.98 (0.62 to 1.57)0.95
MAO-B (females only)NQO10.93 (0.52 to 1.67)
    AG vs AA0.83 (0.40 to 1.69)0.87**
    GG vs AA
MAO-B (males only)DRD2A*1.51 (0.55 to 4.15)0.43
MAO-B (females only)DRD2A‡‡0.71 (0.23 to 2.21)
    AG vs AA0.99 (0.26 to 3.74)0.79**
    GG vs AA
MAO-B (males only)DRD2B0.65 (0.37 to 1.15)0.14
MAO-B (females only)DRD2B‡1.01 (0.50 to 1.99)
    AG vs AA0.58 (0.24 to 1.39)0.37**
    GG vs AA
  • *Logistic regression adjusting for age, sex, country, ever used tobacco containing product, ever knocked unconscious and first degree family history of Parkinson’s disease.

  • **For three category factors p value for trend derived from logistic regression assuming equidistance between genetic categories.

  • ‡Excludes Malta.

  • ‡‡Excludes Sweden and Malta.