Table 4.

Association of low PPI with the presence of the schizophrenia risk allele C of the TCF4 rs9960767 polymorphism in both investigated samples

Criterion for low PPI levelsaSamplesTotal nPPI deficit (n)TCF4 C-allele (n)PPI deficit + TCF4 C-allele (n)Odds ratio95% CIpb
1 SD below normalLondon healthy controls98171266.821.86–24.930.006
Bonn schizophrenia patients + high-risk individuals105411184.931.22–19.850.022
London + Bonn2035823144.811.95–11.870.0009
1.5 SD below normalLondon healthy controls9891234.440.95–20.890.078
Bonn schizophrenia patients + high-risk individuals105321152.070.58–7.350.304
London + Bonn203412382.380.93–6.070.093
  • Bold indicates statistical significance. CI, Confidence interval.

  • aThe healthy London sample refers to itself (mean PPI across 30 ms, 60 ms, and 120 ms SOA conditions: 30.8 ± 17.2% SD), whereas the schizophrenia spectrum Bonn sample refers to a normal population showing a mean PPI of 58.1% (±21.7 SD) at an SOA of 120 ms measured with the same setup (Quednow et al., 2008a).

  • bFisher's exact test.