087). Similar to previous studies, they identified one deletion in a case at 1q21.1, a deletion within NRXN1, and four duplications at 16p13.1 in cases, and one in a control subject. However no deletions were observed at 22q11.2 or

15q13.3 loci. In a reverse trend for the 15q11.2 locus, three deletions were observed in controls compared with one in cases. Based on all the above studies, we may summarize that rare CNVs, until recently, were only thought to play an important role in disorders such as mental Inhibitors,research,lifescience,medical retardation and autism. However, it now appears that CNV make a substantial contribution to the BI 6727 understanding of schizophrenia etiology and pathogenesis. Deletions at 1q21.1, 15q11.2, and 15q13.3 might join the ranks of 22q11.2 as uncommon but important chromosomal aberrations that can lead to severe behavioral disturbances including schizophrenia. What next? Conclusions and future directions Despite decades of research effort, our understanding Inhibitors,research,lifescience,medical of the genesis

of schizophrenia remains an enigma. The methods used for mapping susceptibility genes have progressed enormously over the past several years. The genome-wide studies have pointed to the role of both common variants as Inhibitors,research,lifescience,medical well as rare variants in schizophrenia susceptibility. However, the effect size associated with common variants is smaller than initially estimated (OR<1.2) and only rare variants generally have a large effect. Furthermore, the number of total susceptibility variants for schizophrenia may Inhibitors,research,lifescience,medical be in the order of thousands.114 Considering the low effect size observed for the associated SNPs the sample size required for replicating these associations with adequate power Inhibitors,research,lifescience,medical would theoretically be up to 100 000 each of cases and controls. To achieve such sample sizes with detailed and consistent phenotype measurement is a

formidable challenge. It may be that testing broader phenotypes such as psychosis might help the field to collect these large numbers as well as detect genes which overlap between different disorders. However, the opposite approach may also be valid, that is to narrow 4-Aminobutyrate aminotransferase the phenotype to a hopefully more homogeneous subgroup, for example including use of brain imaging measures, electrophysiology, or carefully defined symptom subtypes. A smaller number of genes of greater effect sizes may influence more refined, specific phenotypes. An interesting outcome of the GWAS data analyses is that there appears to be a considerable overlap between schizophrenia and bipolar disorder, consistent with the idea that they exist on a clinical continuum with overlapping symptom dimensions. A recent study in two million Swedish families also observed that schizophrenia and bipolar disorder share susceptibility genes.