Multiple linkage regions have been reported in schizophrenia, and some appear
Multiple linkage regions have been reported in schizophrenia, and some appear to harbor susceptibility genes that are differentially expressed in postmortem brain tissue derived from unrelated individuals. genes in the 4q33?35.1 haplotype region were also differentially expressed in schizophrenia in postmortem dorsolateral prefrontal cortex: and and regulation of genes. Introduction Genome-wide linkage analysis is an important tool for mapping complex genetic disorders such as schizophrenia. While linkage has been predictably more successful for Mendelian disorders, linkage analysis has identified a number of complex disease loci. To date, multiple linkage regions have been reported in schizophrenia, and some appear to harbor schizophrenia susceptibility genes (O’Donovan et al. 2003; Harrison and Owen 2003). With the exception of a few genes, such as neuregulin 1 (Stefansson et al. 2002) and dysbindin (Straub et al. 2002), there have been no other replicated genes found to be associated with schizophrenia in linkage regions. With a suffcient number of informative meioses (100 to 200) linkage can narrow a buy AZ 10417808 disease gene search for a Mendelian-based disorder to an interval of 1 1 cM. For complex diseases, due to incomplete penetrance and the inability to distinguish phenocopies from true recombination events, typically linkage can only narrow a disease gene search to an area of 10?30 cM. Such regions contain hundreds of potential candidate genes. Additional methods are needed to help prioritize the selection of candidate genes for mutation searches in broad linkage regions. It is known that noncoding variants can alter gene transcription (Knight 2005). Thus, genes that are differentially expressed in linkage regions may be attractive candidates for mutation searches and postmortem expression studies. While access to brain tissue is not possible for living subjects, a readily available and commonly used source of mRNA for expression studies are lymphocytes, due to their availability from living participants. Lymphocyte tissue buy AZ 10417808 is usually of a different embryological origin than brain and does not express all brain relevant genes, while lymphocytes do show abundant expression of genes found in neural tissues (M. P. Vawter, unpublished results). Another advantage buy AZ 10417808 of lymphocyte gene expression is the relative absence of confounding factors, such as postmortem interval, agonal factor, or pH (Vawter et al. 2004; Tsuang et al. 2005). Medications can affect in vivo gene expression, but these effects might be mitigated in transformed lymphocytes utilized in the present study. Moreover, regulatory mutations that alter gene expression in the brain may lead to altered expression in other tissues. It is now possible to study gene expression on a genome-wide basis using high-density microarrays, and such investigations may help identify genes underlying illness within linkage regions. In addition, microarray investigation of gene expression also makes it possible to study whether a gene (or genes) within a linkage region is usually coregulated with transcription of other genes in the genome. Such studies may identify other loci important for schizophrenia as well as regulatory or metabolic pathways underlying the pathophysiology. We have combined genome linkage analysis and genome-wide expression in the present study. Methods Subjects All subjects provided informed consent for genetic mapping studies, and the institutional review board approved all protocols. The multiplex pedigree consisted of 20 members (Fig. 1). Seventeen individuals in the pedigree were initially scanned with microsatellite markers for genome-wide linkage analysis. Ten informative subjects were selected for final screening: five individuals with schizophrenia and the haplotype, and five unaffected controls without the haplotype (Table 1). These Mouse monoclonal to DKK3 10 subjects (Fig. 1) were analyzed by microarray, SNP microarray genotyping, Q-PCR, and mutation scanning. Fig. 1 Multiplex-pedigree showing schizophrenia (recursively varied from 0.05?0.45) and was calculated using LINKAGE software. dChip SNP Linkage and MERLIN (Abecasis et al. 2002) were both used to analyze linkage of phenotype to SNP genotype data. SNP data for autosomal chromosomes were used for linkage analysis in the pedigree by a variant of the LanderCGreen algorithm in the dChip Linkage module of dChip to perform multipoint parametric linkage analysis and compute a LOD score at each SNP position (Lander and Green 1987; Kruglyak et al. 1996, 1995). We verified linkage found with dChip Linkage with MERLIN version 1.0.1 software. The MERLIN software package version 1.0.1 (Abecasis et al. 2002) was used to analyze linkage to the disease with a dominant parametric model for both SNP and MSM markers. In using either MERLIN or dChip Linkage, there was only one suggestive linkage region found in the genome scan at chromosome 4q. MERLIN was used to analyze each quantitative gene expression phenotype from microarray analysis to genetic microsatellite and SNP markers. The linkage of an individual gene expression value as a continuous trait and a microsatellite marker was calculated with MERLIN variance component linkage analysis program. The potential regulatory regions were mapped as cis-regulatory if within 5 Mb of the gene, and trans-regulatory, if >5 Mb from the gene (Morley et al. 2004)..