NRG1 and schizophrenia: In this study, we aim to validate and define potential risk-associated haplotypes of ERBB4 and NRG1 in schizophrenia through a systematic analysis of SNP genotype data from three published genome-wide association studies (GWAS) , CATIE, GAIN and nonGAIN, all of which have large (>500) case-control samples with Caucasian origin.