Genetic research in schizophrenia: new tools and future perspectives.

Genetically, schizophrenia is a complex disease whose pathogenesis is likely governed by a number of different risk factors. While substantial efforts have been made to identify the underlying susceptibility alleles over the past 2 decades, they have been of only limited success. Each year, the field is enriched with nearly 150 additional genetic association studies, each of which either proposes or refutes the existence of certain schizophrenia genes. To facilitate the evaluation and interpretation of these findings, we have recently created a database for genetic association studies in schizophrenia ("SzGene"; available at http://www.szgene.org). In addition to systematically screening the scientific literature for eligible studies, SzGene also reports the results of allele-based meta-analyses for polymorphisms with sufficient genotype data. Currently, these meta-analyses highlight not only over 20 different potential schizophrenia genes, many of which represent the "usual suspects" (eg, various dopamine receptors and neuregulin 1), but also several that were never meta-analyzed previously. All the highlighted loci contain at least one variant showing modest (summary odds ratios approximately 1.20 [range 1.06-1.45]) but nominally significant risk effects. This review discusses some of the strengths and limitations of the SzGene database, which could become a useful bioinformatics tool within the schizophrenia research community.