Initial heritability analyses of endophenotypic measures for schizophrenia: the consortium on the genetics of schizophrenia.
BACKGROUND
Exploration of the genetic architecture of specific endophenotypes may be a powerful strategy for understanding the genetic basis of schizophrenia.


OBJECTIVE
To characterize the genetic architecture of some key endophenotypic measures selected for their reported heritabilities in schizophrenia.


METHODS
Family-based heritability study.


METHODS
Seven sites across the United States.


METHODS
At the time of these initial data analyses, the members of 183 nuclear families ascertained through probands with schizophrenia had been assessed for these endophenotypes.


METHODS
Variance component models were used to assess the heritability of and the environmental and genetic correlations among the endophenotypes. The Consortium on the Genetics of Schizophrenia assesses the neurophysiologic measures of prepulse inhibition of acoustic startle, P50 event-related potential suppression, and the antisaccade task for eye movements and the neurocognitive measures of the Continuous Performance Test (Degraded Stimulus version), the California Verbal Learning Test, the Letter-Number Sequencing test, and 6 measures from the University of Pennsylvania Computerized Neurocognitive Battery. The heritabilities of these 12 measures are the focus of this article.


RESULTS
All of the endophenotypes and the University of Pennsylvania Computerized Neurocognitive Battery measures were found to be significantly heritable (P < or = .005), with heritabilities ranging from 24% to 55%. Significant environmental and genetic correlations were also observed between many of the endophenotypic measures.


CONCLUSIONS
This is the first large-scale, multisite, family-based heritability study of a collection of endophenotypes for schizophrenia and suggests that endophenotypes are important measures to consider in characterizing the genetic basis of schizophrenia.
Greenwood
Tiffany A
TA
Department of Psychiatry, University of California San Diego, La Jolla, USA.
Braff
David L
DL
Light
Gregory A
GA
Cadenhead
Kristin S
KS
Calkins
Monica E
ME
Dobie
Dorcas J
DJ
Freedman
Robert
R
Green
Michael F
MF
Gur
Raquel E
RE
Gur
Ruben C
RC
Mintz
Jim
J
Nuechterlein
Keith H
KH
Olincy
Ann
A
Radant
Allen D
AD
Seidman
Larry J
LJ
Siever
Larry J
LJ
Silverman
Jeremy M
JM
Stone
William S
WS
Swerdlow
Neal R
NR
Tsuang
Debby W
DW
Tsuang
Ming T
MT
Turetsky
Bruce I
BI
Schork
Nicholas J
NJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D004777:Environment; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D040582:Inheritance Patterns; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010375:Pedigree; D010641:Phenotype; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology / Q000235:genetics*; D014481:United States