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 levelsa	Samples	Total n	PPI deficit (n)	TCF4 C-allele (n)	PPI deficit + TCF4 C-allele (n)	Odds ratio	95% CI	pb
1 SD below normal	London healthy controls	98	17	12	6	6.82	1.86–24.93	0.006
	Bonn schizophrenia patients + high-risk individuals	105	41	11	8	4.93	1.22–19.85	0.022
	London + Bonn	203	58	23	14	4.81	1.95–11.87	0.0009
1.5 SD below normal	London healthy controls	98	9	12	3	4.44	0.95–20.89	0.078
	Bonn schizophrenia patients + high-risk individuals	105	32	11	5	2.07	0.58–7.35	0.304
	London + Bonn	203	41	23	8	2.38	0.93–6.07	0.093

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.