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Full genome sequencing of a monozygotic twin discordant for schizophrenia

ABSTRACT: We sequenced the genomes from a monozygotic twin discordant for schizophrenia and a tumor-normal pair of an ovarian cancer patient. Using whole-genome twin data to discriminate between correctly identified single nucleotide variants (SNVs) and errors a strategy for the accurate detection of SNVs was developed. By applying stringent sequencing quality measures, excluding error-prone regions and selecting SNVs identified by different mapping and variation calling algorithms, error rates were ~37-fold reduced. This enabled us to identify the first discordant SNVs in monozygotic twins using whole-genome sequencing. In addition, by showing that novel SNVs are highly enriched in errors, accurate estimates of the number of novel and rare SNVs occurring in unrelated Caucasian individuals were obtained. Finally, somatic mutations in coding and regulatory sequences were reliably identified in the highly rearranged ovarian tumor. Overall, our data demonstrate that strategies to reduce error rates in whole-genomes are required for disease gene discovery.

PROVIDER: EGAS00001000152 | EGA |

REPOSITORIES: EGA

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Project description:We aim to investigate circulating genome-wide microRNA (miRome) profiles in Moyamoya disease (MMD)-discordant monozygotic (MZ) twins with the RNF213 founder mutation (rs112735431).A disease discordant monozygotic twin-based study design may unmask potential confounders from previously published circulating microRNA signature in MMD. Circulating genome-wide microRNA (miRNome) profiling was performed in MMD-discordant monozygotic twins, non-twin-MMD patients, and non-MMD healthy volunteers by microarray followed by qPCRvalidation, using blood samples. Differential plasma-microRNAs were further quantified in endothelial cells differentiated from iPS cell lines (iPSECs) derived from another independent non-twin cohort. Lastly, their target gene expression in the iPSECs was analyzed. Microarray detected 309 plasma-microRNAs in MMD-discordant monozygotic twins that were also detected in the non-twin cohort. Principal component analysis of the plasma-microRNA expression level demonstrated distinct 2 groups separated by MMD and healthy control in the twin- and non-twin cohorts. Of these, differential up-regulations of hsa-miR-6722-3p/-328-3p were validated in the plasma of MMD (Imposed threshold: absolute log2 expression fold change (logFC) > 0.26 for the twin cohort; absolute logFC > 0.26, p < 0.05, and q < 0.15 for the non-twin cohort). In MMD derived iPSECs, hsa-miR-6722-3p/-328-3p showed a trend of up-regulation with a 3.0- or higher expression fold change. Bioinformatics analysis revealed that 41 target genes of miR- 6722-3p/-328-3p were significantly down-regulated in MMD derived iPSECs and were involved in STAT3, IGF-1-, and PTEN-signaling, suggesting a potential microRNA- gene expression interaction between circulating plasma and endothelial cells. In conclusion, our MMD-discordant monozygotic twin-based study confirmed a novel circulating microRNA signature in MMD as a potential diagnostic biomarker minimally confounded by genetic heterogeneity. The novel circulating microRNA signature can contribute for the future functional microRNA analysis to find new diagnostic and therapeutic target of MMD.

Project description:The expression level for 15 887 transcripts in lymphoblastoid cell lines from 19 monozygotic twin pairs (10 male, 9 female) were analysed for the effects of genotype and sex. On an average, the effect of twin pairs explained 31% of the variance in normalized gene expression levels, consistent with previous broad sense heritability estimates. The effect of sex on gene expression levels was most noticeable on the X chromosome, which contained 15 of the 20 significantly differentially expressed genes. A high concordance was observed between the sex difference test statistics and surveys of genes escaping X chromosome inactivation. Notably, several autosomal genes showed significant differences in gene expression between the sexes despite much of the cellular environment differences being effectively removed in the cell lines. A publicly available gene expression data set from the CEPH families was used to validate the results. The heritability of gene expression levels as estimated from the two data sets showed a highly significant positive correlation, particularly when both estimates were close to one and thus had the smallest standard error. There was a large concordance between the genes significantly differentially expressed between the sexes in the two data sets. Analysis of the variability of probe binding intensities within a probe set indicated that results are robust to the possible presence of polymorphisms in the target sequences. Keywords: Monozygotic twin pair Expression Profiles Genome-wide gene expression in lymphoblastoid cell lines was determined using microarrays derived from 15 monozygotic (MZ) twin pairs (10 male, 9 female). 10 twin pair are discordant, 4 are concordant for a disease phenotype and their are 5 controls which have no disease phenotype. This data set was analyzed to interrupt replicated effects of sex and genotype, not disease characteristics. Subsets of these samples have been analyzed separately for disease characteristics, (GSE7036 M-bM-^@M-^S 3 MZ twins discordant for bipolar disorder) and (GSE7486 - 5 discordant and 4 concordant MZ twin pairs with idiopathic absence epilepsies and 5 unaffected MZ twin pairs).

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Full genome sequencing of a monozygotic twin discordant for schizophrenia

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