Genetic association study in schizophrenia and intermediate phenotypes

There is a strong genetic component in the etiology in schizophrenia, the heritability of schizophrenia has been estimated to be approximately 80%. Although linkage studies and whole genome association studies (WGASs) have identified significant association of severeal genes with schizophrenia, no causative gene or locus could be detected yet. Thus we aim to identify further schizophrenia genes in a large case-control study. 950 patients with schizophrenia according to DSM-IV and 200 first degree relatives were included. In addition, 2400 community-based healthy volunteers without relevant somatic, and with no history of psychiatric disorders in themselves and in first-degree relatives entered the study. All subjects are screened by SCID and characterized by other specific instruments. Furthermore all subjects accomplished several neurophysiological tests to investigate intermediate phenotypes as a complementary approach. Furthermore, 1000 Single Nucleotide Polymorphisms (SNPs) were selected (tag SNPs in addition to common functional variants and published candidate SNPs localized in selected genes) and high-throughput genotyping was performed using IPLEX Assay and MALDI TOF. We present here data on the influence of common genetic variations on individual differences on cognitive performance and schizophrenia.