Project description:Autism is currently considered a multigene disorder with epigenetic influences. To investigate the contribution of DNA methylation to autism spectrum disorders, we have recently completed large-scale methylation profiling by CpG island microarray analysis of lymphoblastoid cell lines (LCL) derived from monozygotic twins discordant for diagnosis of autism and their nonautistic siblings. Methylation profiling revealed many candidate genes differentially methylated between discordant MZ twins as well as between both twins and nonautistic siblings. Bioinformatics analysis of the differentially methylated genes demonstrated enrichment for high level functions including gene transcription, nervous system development, cell death/survival, and other biological processes implicated in autism. The methylation status of two of these candidate genes, BCL-2 and retinoic acid receptor (RAR)-related orphan receptor alpha (RORA), was further confirmed by bisulfite sequencing and methylation-specific PCR, respectively. Immunohistochemical analyses of tissue arrays containing slices of the cerebellum and frontal cortex of autistic and age- and sex-matched control subjects revealed decreased expression of RORA and BCL-2 proteins in the autistic brain. Our data thus confirm the role of epigenetic regulation of gene expression via differential DNA methylation in idiopathic autism, and furthermore link molecular changes in a peripheral cell model with brain pathobiology in autism. Global methylation profiling was performed on lymphoblastoid cell lines (LCLs) derived from three pairs of male monozygotic twins discordant for diagnosis of autism as determined by the Autism Diagnostic Interview-Revised (ADI-R). As controls, cell lines derived from non-autistic siblings of two pairs of twins were also included in the analyses, in addition to cell lines derived from a set of monozygotic twins unaffected by autism. For all paired analyses, a direct comparison was performed in which the methylation-enriched fractions from two individuals were pooled and hybridized onto the same microarray. In addition, indirect comparisons were performed by co-hybridizing the methylation-enriched (MIRA) fraction with the respective unenriched DNA fraction obtained from the same individual. For each paired analysis (between autistic MZ twins and/or between autistic co-twin and unaffected sibling), a total number of 4 replicates were performed, including direct and indirect comparisons.
Project description:Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by abnormalities in reciprocal social interactions and language development and/or usage, and by restricted interests and repetitive behaviors. Differential gene expression of neurologically relevant genes in lymphoblastoid cell lines from monozygotic twins discordant in diagnosis or severity of autism suggested that epigenetic factors such as DNA methylation or microRNAs (miRNAs) may be involved in ASD. The goal of this study was to reveal dysregulation in miRNA levels that are inversely correlated with altered levels of target genes that, in turn, may be associated with the underlying pathophysiology of ASD, and to provide a better understanding of the role of miRNAs as a post-transcriptional gene regulatory mechanism associated with ASD. Lymphoblastoid cell lines (LCLs) derived from peripheral lymphocytes of 14 male subjects were obtained from the Autism Genetic Resource Exchange (AGRE, Los Angeles, CA). The subjects included three pairs of monozygotic twins discordant for diagnosis of autism, a normal sibling for 2 of the twin pairs, two pairs of autistic and unaffected siblings, and a pair of normal monozygotic twins. Global miRNA expression profiling of these LCLs was performed using high-throughput miRNA microarray analysis. A reference design was used for microarray hybridization in this study. The sample miRNAs were coupled with Cy3, whereas the common reference miRNA was coupled with Cy5, and two-colored miRNA microarray analyses were carried out by cohybridizing an equal amount of both miRNA samples onto one slide. Selected differentially expressed miRNAs were confirmed by quantitative RT-PCR, and the putative target genes of two of the confirmed miRNAs were validated by knockdown and overexpression of the respective miRNAs.
Project description:Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by abnormalities in reciprocal social interactions and language development and/or usage, and by restricted interests and repetitive behaviors. Differential gene expression of neurologically relevant genes in lymphoblastoid cell lines from monozygotic twins discordant in diagnosis or severity of autism suggested that epigenetic factors such as DNA methylation or microRNAs (miRNAs) may be involved in ASD. The goal of this study was to reveal dysregulation in miRNA levels that are inversely correlated with altered levels of target genes that, in turn, may be associated with the underlying pathophysiology of ASD, and to provide a better understanding of the role of miRNAs as a post-transcriptional gene regulatory mechanism associated with ASD.
Project description:Autism is currently considered a multigene disorder with epigenetic influences. To investigate the contribution of DNA methylation to autism spectrum disorders, we have recently completed large-scale methylation profiling by CpG island microarray analysis of lymphoblastoid cell lines (LCL) derived from monozygotic twins discordant for diagnosis of autism and their nonautistic siblings. Methylation profiling revealed many candidate genes differentially methylated between discordant MZ twins as well as between both twins and nonautistic siblings. Bioinformatics analysis of the differentially methylated genes demonstrated enrichment for high level functions including gene transcription, nervous system development, cell death/survival, and other biological processes implicated in autism. The methylation status of two of these candidate genes, BCL-2 and retinoic acid receptor (RAR)-related orphan receptor alpha (RORA), was further confirmed by bisulfite sequencing and methylation-specific PCR, respectively. Immunohistochemical analyses of tissue arrays containing slices of the cerebellum and frontal cortex of autistic and age- and sex-matched control subjects revealed decreased expression of RORA and BCL-2 proteins in the autistic brain. Our data thus confirm the role of epigenetic regulation of gene expression via differential DNA methylation in idiopathic autism, and furthermore link molecular changes in a peripheral cell model with brain pathobiology in autism.
Project description:Autism spectrum disorder(ASD) is a complex neurodevelopmental disorder. Aberrant DNA methylation has been observed in ASD but the mechanisms remain largely unknown. Here, we employed discordant monozygotic twins to investigate the contribution of DNA methylation to ASD etiology. Genome-wide DNA methylation analysis was performed using samples obtained from five pairs of ASD-discordant monozygotic twins, which revealed a total of 2397 differentially methylated genes. Further, such gene list was annotated with Kyoto Encyclopedia of Genes and Genomes and demonstrated predominant activation of neurotrophin signaling pathway in ASD-discordant monozygotic twins. The methylation of SH2B1 gene was further confirmed in the ASD-discordant, ASD-concordant monozygotic twins, and a set of 30 pairs of sporadic case-control by bisulfite-pyrosequencing. The results showed that there was a greater DNA methylation difference in ASD-discordant monozygotic twins than ASD-concordant monozygotic twins. Further, verification of the Chr.16:28856743 of SH2B1 showed significant differences in DNA methylation between case and control. These results suggest abnormal methylation of SH2B1 is associated with ASD etiology. Our data suggest that it might be worthwhile to further explore the functions of SH2B1 and related genes of neurotrophin signaling pathway in ASD.
Project description:Autism spectrum disorder(ASD) is a complex neurodevelopmental disorder. Aberrant DNA methylation has been observed in ASD but the mechanisms remain largely unknown. Here, we employed discordant monozygotic twins to investigate the contribution of DNA methylation to ASD etiology. Genome-wide DNA methylation analysis was performed using samples obtained from five pairs of ASD-discordant monozygotic twins, which revealed a total of 2397 differentially methylated genes. Further, such gene list was annotated with Kyoto Encyclopedia of Genes and Genomes and demonstrated predominant activation of neurotrophin signaling pathway in ASD-discordant monozygotic twins. The methylation of SH2B1 gene was further confirmed in the ASD-discordant, ASD-concordant monozygotic twins, and a set of 30 pairs of sporadic case-control by bisulfite-pyrosequencing. The results showed that there was a greater DNA methylation difference in ASD-discordant monozygotic twins than ASD-concordant monozygotic twins. Further, verification of the Chr.16:28856743 of SH2B1 showed significant differences in DNA methylation between case and control. These results suggest abnormal methylation of SH2B1 is associated with ASD etiology. Our data suggest that it might be worthwhile to further explore the functions of SH2B1 and related genes of neurotrophin signaling pathway in ASD.
Project description:Human intelligence demonstrates one of the highest heritabilities among human quantitative traits. Phenotypically discordant monozygotic twins provide a way to identify loci responsible for normal-range intelligence. We conducted array-based genome-wide gene expression analysis aiming to identify genes displaying significant difference among monozygotic twin pairs manifesting between-co-twins IQ differences. Total RNA was isolated from B-lymphoblastoid cell lines and applied to Affymetirx arrays after reverse transcription. 17 twin pairs (34 subjects) were recruited in this study.
Project description:Background: The autism spectrum includes a set of complex multigenic developmental disorders that severely impact the development of language, non-verbal communication, and social skills, and are associated with odd, stereotyped, repetitive behavior and restricted interests. To date, diagnosis of these neurologically based disorders relies predominantly upon behavioral observations often prompted by delayed speech or aberrant behavior, and there are no known genes that can serve as definitive biomarkers for the disorders. Results: Here we demonstrate, for the first time, that lymphoblastoid cell lines from monozygotic twins discordant with respect to severity of autism and/or language impairment exhibit differential gene expression patterns on DNA microarrays. Furthermore, we show that genes important to the development, structure, and/or function of the nervous system are among the most differentially expressed genes, and that many of these genes map in silico to chromosomal regions containing autism susceptibility genes or quantitative trait loci. Conclusions: Our present results provide compelling evidence that candidate genes for autism may be expressed in lymphoid cell lines from individuals with autism spectrum disorders. This finding further suggests the possibility of developing a molecular screen for autism using peripheral blood lymphocytes, an easily accessible tissue. In addition, gene networks are identified that may play a role in the pathophysiology of autism. Keywords: DNA microarrays, comparison expression profiling, relation to autistic phenotype
Project description:To identify genes dysregulated in bipolar disorder (BD1) we carried out global gene expression profiling using whole-genome microarrays. To minimize genetic variation in gene expression levels between cases and controls we compared expression profiles in lymphoblastoid cell lines from monozygotic twin pairs discordant for the disease. We identified 82 genes that were differentially expressed by ≥ 1.3-fold in 3 BD1 cases compared to their co-twins, and which were statistically (p ≤ 0.05) differentially expressed between the groups of BD1 cases and controls. Using qRT-PCR we confirmed the differential expression of some of these genes, including: KCNK1, MAL, PFN2, TCF7, PGK1, and PI4KCB, in at least 2 of the twin pairs. In contrast to the findings of a previous study by Kakiuchi and colleagues with similar discordant BD1 twin design1 our data do not support the dysregulation of XBP1 and HSPA5. From pathway and gene ontology analysis we identified up-regulation of the WNT signalling pathway and the biological process of apoptosis. The differentially regulated genes and pathways identified in this study may provide insights into the biology of BD1. Keywords: Bipolar Disorder, Monozygotic Twins, Discordant, Trasnsformed Lymphocytes