Project description:Turner Syndrome (TS) is a rare cytogenetic disorder caused by the complete loss or structural variation of the second sex chromosome. The most common cause of early mortality in TS results from a high incidence of left-sided congenital heart defects, including bicuspid aortic valve (BAV), which occurs in about 30% of individuals with TS. BAV is also the most common congenital heart defect in the general population with a prevalence of 0.5-2%, with males being three-times more likely to have a BAV than females. TS is associated with genome wide hypomethylation when compared to karyotypically normal males and females. Alterations in DNA methylation in primary aortic tissue are associated with BAV in euploid individuals. Here we show significant differences in DNA methylation patterns associated with BAV in TS found in peripheral blood. When comparing TS with BAV to TS with no heart defects we identified a differentially methylated region encompassing the BAV-associated gene MYRF, and enrichment for binding sites of two known transcription factor contributors to BAV. When comparing TS with BAV to euploid women with BAV, we found significant overlapping enrichment for ChIP-seq transcription factor targets including genes in the NOTCH1 pathway, known for involvement in the etiology of non-syndromic BAV, and other genes that are essential regulators of heart valve development. Overall, these findings suggest that altered DNA methylation affecting key aortic valve development genes contributes to the greatly increased risk for BAV in TS.
Project description:X chromosome inactivation (XCI) is a dosage compensation mechanism that silences the majority of genes on one X chromosome in each female cell. In order to characterize epigenetic changes that accompany this process, we measured DNA methylation levels in both 45,X Turner syndrome patients, who carry a single active X chromosome (Xa) and normal 46,XX females, who carry one Xa and one inactive X (Xi). Methylated DNA was immunoprecipitated and hybridized to tiling oligonucleotide arrays, generating epigenetic profiles of active and inactive X chromosomes. We observed that XCI is accompanied by changes in DNA methylation specifically at CpG islands. While the majority of CpG islands show increased methylation levels on the Xi, XCI results in reduced methylation at ~20% of CpG islands. Both intra- and inter-genic CpG islands are epigenetically modified, with the biggest increase in methylation occuring at the promoters of genes silenced by XCI. In contrast, genes escaping XCI have low levels of promoter methylation, while genes that undergo polymorphic silencing show intermediate increases in methylation proportionate to their frequency of inactivation. Thus promoter methylation and susceptibility to XCI are correlated. We observed a global correlation between CpG island methylation and the evolutionary age of different X chromosome strata, and that genes escaping XCI show increased methylation within gene bodies. We utilized our epigenetic map to predict both novel genes escaping XCI, and to identify sequence features that may contribute to the XCI process. Finally, as our study included Turner syndrome patients with single X chromosomes of both maternal and paternal origin we searched for parent-of-origin specific methylation differences, but found no evidence to support imprinting on the human X chromosome. Our study provides the first epigenetic profile of active and inactive X chromosomes, giving novel insights into the phenomenon of dosage compensation. Methylated DNA was enriched by immunoprecipitation using antibodies against 5-methylcytosine. meDIP and input DNA was labeled with cy5 and cy3 respectively and hybridized to Nimblegen arrays comprising 2.1 million 50-85mers covering human chromosomes 20, 21, 22, X and Y at a mean density of ~1 probe per 100bp. Resulting log2 fluorescence ratios correspond to methylation levels. Seven patients with Turner syndrome (45,X karyotype), and three normal females (46,XX karyotype) were analyzed. Of the Turner syndrome cases, four had a maternally-derived X, and three had a paternally-derived X chromosome.
Project description:We have generated iPSCs from monosomy X (Turner Syndrome), trisomy 8 (Warkany Syndrome 2), trisomy 13 (Patau Syndrome) and partial trisomy 11;22 (Emanuel Syndrome), using either skin fibroblasts from affected individuals or amniocytes from antenatal diagnostic tests. These cell lines stably maintain the karyotype of the donors and behave like embryonic stem cells (ESCs) in all tested assays. Turner Syndrome iPSCs were used for further studies including global gene expression analysis and tissue-specific directed differentiation. Multiple clones displayed lower levels of the pseudoautosomal genes ASMTL and PPP2R3B than the controls. Moreover, they could be transformed into neural-like, hepatocyte-like and heart-like cells but displayed insufficient up-regulation of the pseudoautosomal placental gene CSF2RA during embryoid body (EB) formation. These data support that abnormal organogenesis and early lethality in Turner Syndrome are not caused by a tissue-specific differentiation blockade but rather involves other abnormalities including impaired placentation. Global gene expression profiling with DNA microarrays showed that 3 TS iPSC clones corresponding to the same patient showed a global gene expression pattern similar to ESCs and euploid iPSCs, and very different from donor cells .We detected transcriptomic changes between TS iPSCs and the other ESCs/iPSCs but these variations did not follow a pattern and in fact all pluripotent cell lines clustered together. For DNA microarray analysis, all cells were treated with Trizol, followed by RNA extraction and hybridization.
Project description:Turner syndrome is a relatively rare condition that is usually associated with the loss of all or part of an X chromosome. Amniotic fluid is a complicated biological material, could contribute to the understanding of turner syndrome pathogenesis. In this study, ATAC-seq analysis of Turner syndrome (45X) and Female (46XX) amniotic fluid cells was applied to illustrate that genome wide chromatin accessible landscapes. Our results show that Turner Syndrome has higher chromatin accessibility than Female on autosomes and has lower chromosome accessibility on the X chromosome. We identified candidate genomic regions and transcript factors that may play an important role in Turner syndrome pathogenesis. Our analysis suggests that the phenotype of Turner Syndrome should be the result of abnormal regulation of gene expression in the whole genome, not just the result of insufficient doses of X chromosome haploids.
Project description:Human DNA methylation Beadchip v1.2 was used to obtain n=113 Illumina DNA methylation array from whole blood samples. The main goal of the study was to measure the epigenetic age (also known as DNA methylation age) of subjects with a severe developmental disorder (known as syndrome X) and controls. To measure DNA methylation age, we used the epigenetic clock software described in Horvath S (n=2013) DNA methylation age of human tissues and cell types. Genome Biology.2013, 14:R115. DOI: 10.1186/10.1186/gb-2013-14-10-r115 PMID: 24138928. The data set contains 5 affected female subjects who exhibit a pure form of syndrome X. Further, the study includes two syndrome X-like subjects who also have Down syndrome and Ring- X Turner syndrome, respectively. For the diseased subjects, we collected several family members (parents and possibly siblings). We also collected several control families who do not have an affected child. Apart from family data, we also analyzed 62 blood samples from healthy controls.
Project description:We have generated iPSCs from monosomy X (Turner Syndrome), trisomy 8 (Warkany Syndrome 2), trisomy 13 (Patau Syndrome) and partial trisomy 11;22 (Emanuel Syndrome), using either skin fibroblasts from affected individuals or amniocytes from antenatal diagnostic tests. These cell lines stably maintain the karyotype of the donors and behave like embryonic stem cells (ESCs) in all tested assays. Turner Syndrome iPSCs were used for further studies including global gene expression analysis and tissue-specific directed differentiation. Multiple clones displayed lower levels of the pseudoautosomal genes ASMTL and PPP2R3B than the controls. Moreover, they could be transformed into neural-like, hepatocyte-like and heart-like cells but displayed insufficient up-regulation of the pseudoautosomal placental gene CSF2RA during embryoid body (EB) formation. These data support that abnormal organogenesis and early lethality in Turner Syndrome are not caused by a tissue-specific differentiation blockade but rather involves other abnormalities including impaired placentation.
Project description:This SuperSeries is composed of the following subset Series: GSE41751: Correlated alterations in genome organization, histone methylation, and DNA-lamina interactions in Hutchinson-Gilford progeria syndrome (expression) GSE41757: Correlated alterations in genome organization, histone methylation, and DNA-lamina interactions in Hutchinson-Gilford progeria syndrome (ChIP-seq) GSE41763: Correlated alterations in genome organization, histone methylation, and DNA-lamina interactions in Hutchinson-Gilford progeria syndrome (Hi-C) Refer to individual Series
Project description:Genomewide methylation analysis in Silver Russell syndrome patients compared to healthy controls Bisulphite converted DNA from the 24 samples were hybridised to the Illumina Infinium 450k Human Methylation Beadchip