Dataset Information

Genome, Epigenome and RNA Sequences of MZ Twins Discordant for MS

ABSTRACT:

Monozygotic (MZ) twins have been widely employed for dissection of the relative contributions of genetics and environment in disease. In multiple sclerosis (MS), an autoimmune demyelinating disease that commonly causes neurodegeneration and disability in young adults, disease discordance in MZ twins has been interpreted to indicate environmental importance in pathogenesis. However, genetic and epigenetic differences between MZ twins have been described, challenging the accepted experimental paradigm in disambiguating effects of nature and nurture. Here, we report the genome sequences of one MS-discordant MZ twin pair and messenger RNA (mRNA) transcriptome and epigenome sequences of CD4+ lymphocytes from three MS-discordant, MZ twin pairs. No reproducible differences were detected between co-twins among ~3.6 million single nucleotide polymorphisms (SNPs) or ~0.2 million insertion-deletion polymorphisms (indels). Nor were any reproducible differences observed between siblings of the three twin pairs in HLA haplotypes, confirmed MS-susceptibility SNPs, copy number variations, mRNA and genomic SNP and indel genotypes, or expression of ~19,000 genes in CD4+ T cells. Only two to 176 differences in methylation of ~2 million CpG sites were detected between siblings of the three twin pairs, in contrast to ~800 differences in methylation between T cells of unrelated individuals and several thousand differences between tissues or normal and cancerous tissues. In the first systematic effort to estimate sequence variation among MZ co-twins, we did not find evidence for genetic, epigenetic or transcriptome differences that explained disease discordance. These are the first female, twin and autoimmune disease genome sequences reported.

PROVIDER: phs000239 | dbGaP |

SECONDARY ACCESSION(S): PRJNA74839PRJNA74841

REPOSITORIES: dbGaP

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Dataset's files

Source:

			Action	DRS
	Study_Report.phs000239.NINDS_MS_MZTwins.v1.p1.MULTI.pdf	Pdf
	manifest_phs000239.NINDS_MS_MZTwins.v1.p1.c1.GRU.pdf	Pdf
	sra_manifest_phs000239.NINDS_MS_MZTwins.v1.p1.c1.GRU.txt	Txt
	datadict_v2.xsl	Other
	phs000239.v1.pht001219.v1.MS_MZTwins_Subject.data_dict_2010_05_17.xml	Xml

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Project description:DNA methylation appears to play an essential mechanistic role in the pathogenesis of ALL, thereby potentiate its use as a biomarker for diagnosis and prognosis (Milani, Lundmark et al. 2010; Geng, Brennan et al. 2012; Sandoval, Heyn et al. 2013), and even a potential target of novel therapeutic approaches in ALL. In present study, we collected blood specimens for 4 pairs of monozygotic twins (MZ) and 1 pair of dizygotic twin (DZ) that are discordant for ALL. We sought to comprehensively assess the magnitude of genetic and epigenetic differences between ALL-affected and unaffected twins. we conducted whole genome and whole methylome sequencing on these five pairs of ALL-discordant twins. We also examined both the MZ and DZ twins using whole-genome bisulfite sequencing (WGBS). At first, the methylation differences across the genome were addressed globally by Circos software. And then tried to characterize the co-twin methylation divergence in specific genomic regions between ALL-discordant twin pairs. These patterns of dynamic co-twin methylation changes in these discordant ALL samples were generally consistent among MZ and DZ twins, indicating similarities of methylation abnormalities. As a result, 780, 566, 309, 293 and 2110 DMRs were identified, with a similar distribution pattern across different genomic elements among the five twin pairs.Then we annotate whether these DMRs were located in regulatory elements and identification of genes with recurring methylation alterations in a cohort of ALL patients. We collected blood specimens from 4 pairs of MZ twins and 1 pair of DZ twin that are discordant for ALL. At first, the methylation differences across the genome were addressed globally by Circos software. And then tried to characterize the co-twin methylation divergence in specific genomic regions and differentially methylated gene regions (DMRs) were identified between ALL-discordant twin pairs. Then we annotate whether these DMRs were located in regulatory elements and identification of genes with recurring methylation alterations in a cohort of ALL patients.

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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Genome, Epigenome and RNA Sequences of MZ Twins Discordant for MS

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