VSD: a database for schizophrenia candidate genes focusing on variations

Schizophrenia is a common mental disease characterized by delusions, hallucinations, and formal thought disorder. It has been demonstrated with genetic evidence that the disease is a polygenic disorder. Pharmacological, neurochemical, and clinical studies have suggested a number of schizophrenia susceptibility loci. In order to systematically search for genes with small effect in the development of schizophrenia, a database called VSD was established to provide variation data for publicly available candidate genes. Most of the genes encode neurotransmitter receptors, neurotransmitter transporters, and the enzymes involved in their metabolism. Other candidate genes extracted from published literature are also included. The variation information has been collected from publicly available mutation and polymorphism databases such as dbSNP, HGVbase, and OMIM, with single nucleotide polymorphism (SNP) being the most abundant form of collected variations. Reference sequences from NCBI's RefSeq database are used as references when positioning variation at transcript and protein levels. The nonsynonymous SNPs (nsSNPs) that lead to amino acid changes in the functional sites or domains of proteins are distinguished since they are more likely to affect protein function and would be target SNPs for association studies. In addition to variation data, gene descriptions, enzyme information, and other biological information for each gene locus are also included. The latest version of VSD contains 23,648 variations assigned to a total of 186 genes. Five-hundred eighty-eight domains and sites annotated in the SWISS-PROT and InterPro databases are found to contain nsSNPs. VSD may be accessed via the World Wide Web (www.chgb.org.cn/vsd.htm) and will be developed as an up-to-date and comprehensive locus-specific resource for identifying susceptibility genes for schizophrenia.