Table 2.

Differential Heritability of PPI and P50 Gating Measures in Nuclear Families with Positive vs. Negative Family History

Endophenotype	All 296 Families			97 FH+ Families			96 FH− Families
	No.	h2r ± SE	P value	No.	h2r ± SE	P value	No.	h2r ± SE	P value
PPI	701	0.29 ± 0.09	0.0004	242	0.47 ± 0.13	0.017	215	0.02 ± 0.17	ns
Startle Magnitude	821	0.62 ± 0.07	<0.0001	278	0.54 ± 0.11	<0.0001	259	0.60 ± 0.14	<0.0001
P50 Gating	568	0.20 ± 0.10	0.019	192	0.36 ± 0.17	0.011	175	0.03 ± 0.17	ns
P50 S1	564	0.39 ± 0.10	<0.0001	190	0.80 ± 0.20	<0.0001	175	0.35 ± 0.20	0.034
P50 S2	564	0.27 ± 0.11	0.005	191	0.19 ± 0.18	ns	174	0.36 ± 0.19	0.026
Continuous Performance Test	881	0.34 ± 0.06	<0.0001	294	0.31 ± 0.11	0.001	283	0.29 ± 0.12	0.005
Letter-Number Span	951	0.34 ± 0.06	<0.0001	320	0.31 ± 0.11	0.001	301	0.41 ± 0.13	<0.0001
Verbal Learning	949	0.26 ± 0.06	<0.0001	323	0.28 ± 0.12	0.004	299	0.31 ± 0.10	0.001

Key: FH+ = multiply affected families with a positive history for schizophrenia and/or bipolar disorder; FH− = singleton families with only the required schizophrenia proband and no evidence of other major psychiatric disorders. Nonsignifcant p values >0.10 are indicated as “ns”. For the cognitive measures shown for comparison, Continuous Performance Test refers to the Degraded Stimulus version d′ measure, Letter-Number Span was the reordered condition, and Verbal Learning refers to the California Verbal Learning Test list A total recall score.