Molecular Phenotype of Constitutional TET2 Haploinsufficiency in Humans
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PROVIDER: EGAS00001003454 | EGA |
REPOSITORIES: EGA
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Project description:In order to investigate whether carriers of BRCA1 heterozygous mutation show altered miRNA expression profiles, we established a panel of lymphoblastoid cell lines (LCLs) harboring either mutated or WT BRCA1 (control) and investigated their miRNA expression profiles. We were especially interested whether we find differences in miRNA expression between carriers of missense versus truncating mutation in BRCA1 gene. We evaluated the miRNA expression in a panel of 21 non-treated lymphoblastoid cell lines (LCLs). Among them, 6 LCLs with WT BRCA1, 5 LCLs carrying missense mutation in BRCA1, and 10 LCLs harboring truncating mutation in BRCA1 were included in this study.
2015-12-31 | E-GEOD-60444 | biostudies-arrayexpress
Project description:In order to investigate whether carriers of BRCA1 heterozygous mutation show altered gene expression profiles, we used a whole genome microarray expression profiling of a panel of lymphoblastoid cell lines (LCLs) harboring either mutated or WT BRCA1 (control). We were especially interested whether we find differences in gene expression between carriers of missense versus truncating mutation in BRCA1 gene. We evaluated gene expression of a panel of 21 non-treated lymphoblastoid cell lines (LCLs). Among them, 6 LCLs with WT BRCA1, 5 LCLs carrying missense mutation in BRCA1, and 10 LCLs harboring truncating mutation in BRCA1 were included in this study.
2015-12-31 | E-GEOD-60396 | biostudies-arrayexpress
Project description:Epigenetic modifying enzymes DNMT3A and TET2 are recurrently mutated in hematological disorders despite possessing opposing biochemical functions in the DNA methylation processes. Using conditional ablation, we show these contrasting genotypes result in different functional effects in hematopoietic stem cells (HSCs). Loss of Dnmt3a bestows enhanced self-renewal on HSCs in serial, competitive repopulation assays while Tet2 loss functionally depletes HSCs after a tertiary transplant despite an initial competitive advantage. Moreover, loss of Tet2 sensitizes HSCs to the addition of a common leukemic driver mutation Flt3-ITD. Tet2-null mice experience a 5-fold decrease in median survival time when combined with Flt3-ITD while that of Dnmt3a-null mice decreases 1.5-fold. Molecular characterization of transcriptomes and chromatin accessibility reflects the functional differences between the genotypes as Dnmt3a-null cells reside in a more stem cell-like state while Tet2 loss leads to functional attrition of down-stream progenitors. These data further prove that DNMT3A and TET2 mutations lead HSCs down different molecular and functional pathways despite similar disease destinations.
2020-04-01 | GSE139911 | GEO
Project description:In order to investigate whether carriers of BRCA1 heterozygous mutation show altered miRNA expression profiles, we established a panel of lymphoblastoid cell lines (LCLs) harboring either mutated or WT BRCA1 (control) and investigated their miRNA expression profiles. We were especially interested whether we find differences in miRNA expression between carriers of missense versus truncating mutation in BRCA1 gene.
2015-12-31 | GSE60444 | GEO
Project description:In order to investigate whether carriers of BRCA1 heterozygous mutation show altered gene expression profiles, we used a whole genome microarray expression profiling of a panel of lymphoblastoid cell lines (LCLs) harboring either mutated or WT BRCA1 (control). We were especially interested whether we find differences in gene expression between carriers of missense versus truncating mutation in BRCA1 gene.
2015-12-31 | GSE60396 | GEO
Project description:Germline mutations in fundamental epigenetic regulatory molecules including DNA methyltransferase 3A (DNMT3A) are commonly associated with growth disorders, whereas somatic mutations are often associated with malignancy. We profiled genome-wide DNA methylation patterns in DNMT3A c.2312G>A; p.(Arg771Gln) carriers in a large Amish sibship with Tatton-Brown-Rahman syndrome (TBRS) and their mosaic father. This defined widespread DNA hypomethylation at specific genomic sites enriched at locations annotated to genes involved in morphogenesis, development, differentiation, and malignancy predisposition pathways. TBRS patients also displayed highly accelerated DNA methylation aging.
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Project description:Background: Constitutional MLH1 epimutations are characterized by monoallelic methylation of the MLH1 promoter throughout normal tissues, accompanied by allele-specific silencing. The mechanism underlying primary MLH1 epimutations is currently unknown. The aim of this study was to perform an in-depth characterization of constitutional MLH1 epimutations targeting the aberrantly methylated region around MLH1 and other genomic loci. Methods: Twelve MLH1 epimutation carriers, 61 Lynch syndrome patients and 41 healthy controls, were analyzed by Infinium Human Methylation 450K beadchip, and targeted molecular techniques were used to characterize the MLH1 epimutation in carriers and their inheritance pattern. Results: No nucleotide or structural variants were identified in-cis on the epimutated allele in ten carriers, in which intergenerational methylation erasure was demonstrated in two, suggesting primary type of epimutation. CNVs outside the MLH1 locus were found in two cases. EPM2AIP1-MLH1 CpG island was identified as the sole differentially methylated region in MLH1 epimutation carriers compared to controls. Conclusion: Primary constitutional MLH1 epimutations arise as a focal epigenetic event at the EPM2AIP1-MLH1 CpG island in the absence of cis-acting genetic variants. Further molecular characterization is needed to elucidate the mechanistic basis of MLH1 epimutations and their heritability/reversibility.
2017-11-28 | GSE107351 | GEO
Project description:Background: Constitutional MLH1 epimutations are characterized by monoallelic methylation of the MLH1 promoter throughout normal tissues, accompanied by allele-specific silencing. The mechanism underlying primary MLH1 epimutations is currently unknown. The aim of this study was to perform an in-depth characterization of constitutional MLH1 epimutations targeting the aberrantly methylated region around MLH1 and other genomic loci. Methods: Twelve MLH1 epimutation carriers, 61 Lynch syndrome patients and 41 healthy controls, were analyzed by Infinium Human Methylation 450K beadchip, and targeted molecular techniques were used to characterize the MLH1 epimutation in carriers and their inheritance pattern. Results: No nucleotide or structural variants were identified in-cis on the epimutated allele in ten carriers, in which intergenerational methylation erasure was demonstrated in two, suggesting primary type of epimutation. CNVs outside the MLH1 locus were found in two cases. EPM2AIP1-MLH1 CpG island was identified as the sole differentially methylated region in MLH1 epimutation carriers compared to controls. Conclusion: Primary constitutional MLH1 epimutations arise as a focal epigenetic event at the EPM2AIP1-MLH1 CpG island in the absence of cis-acting genetic variants. Further molecular characterization is needed to elucidate the mechanistic basis of MLH1 epimutations and their heritability/reversibility.
2017-11-28 | GSE107352 | GEO
Project description:Lynch syndrome, caused by germline heterozygous mutations of the DNA mismatch repair genes MLH1, MSH2, MSH6 and PMS2, or deletions affecting the EPCAM gene upstream of MSH2, is characterized by a predisposition to early-onset colorectal and additional extracolonic cancers. An alternative but rare cause of Lynch syndrome is a constitutional epimutation of MLH1, which is characterized by promoter methylation and transcriptional silencing of a single allele in normal tissues. Worldwide, five families with autosomal dominant transmission of a constitutional MLH1 epimutation linked to an MLH1 haplotype with two single nucleotide variants (c.-27C>A and c.85G>T) have been identified. Array-based genotyping using Affymetrix SNP 6.0 data in four of these families revealed a shared haplotype extending across a ≤2.6 Mb region of chromosome 3p22 encompassing MLH1 and additional flanking genes, indicating common ancestry. Genomic DNA from 5 carriers of the c.-27C>A and c.85G>T variants was hybridized on Affymetrix SNP6.0 array according to manufacturer's procedures
2013-04-01 | E-GEOD-45149 | biostudies-arrayexpress
Project description:Constitutional MLH1 epimutations are a rare cause of Lynch syndrome. Low methylation levels (≤10%) have been occasionally described. The aim of this study was the identification of patients with low levels of epigenetic mosaicism in MLH1 gene. Eighteen patients with MLH1 hypermethylated tumors and undetectable methylation in blood as assessed by Methylation-Specific Multiplex Ligation-Dependent Probe Amplification were included (MS-MLPA). Highly sensitive MS-Melting Curve Analysis (MS-MCA) at MLH1 promoter was used to screen for epigenetic mosaicism. Constitutional methylation was confirmed by other methods. Mutational analysis of hereditary cancer genes including MLH1 was performed. MS-MCA analysis identified one case (5.6%) with low levels of methylation (1-2%) in blood DNA. The patient had developed 3 gastrointestinal tumors at ages 22, 24 and 25, sharing MLH1 promoter hypermethylation and loss of heterozygosity associated with c.655A allele. The presence of low MLH1 methylation levels was confirmed by clonal bisulfite sequencing, evidencing the association with c.-93G allele (in phase with c.655G). The extension of the hypermethylated region overlaps with the reported in constitutional MLH1 epimutation carriers. No rare germline variants were identified. The use of highly sensitive techniques such as MS-MCA has demonstrated to be useful for the detection of low MLH1 methylation levels in blood.
2019-05-22 | GSE131541 | GEO