3330 results for "*geneti*"

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• Clinical and genetic analysis of a rare syndrome associated with neoteny

  We describe a novel syndrome in six patients with extreme developmental delay and the defining characteristic of neoteny. In an effort to discover any genetic causes of this syndrome whole genome sequence (WGS) analysis of the patients and their families was performed on Complete Genomics’ nanoarray platform.

  Study EGAS00001002419

• The evolutionary trajectory of a highly recurrent paediatric high grade neuroepithelial tumour with MN1:BEND2 fusion

  Astroblastomas are rare brain tumours which predominate in children and young adults, and have a controversial claim as a distinct entity, with no established WHO grade. Reports suggest a better outcome than high grade gliomas, though they frequently recur. Recently, they have been described to overlap with a newly-discovered group of tumours described as ’high grade neuroepithelial tumour with MN1 alteration’ (CNS HGNET-MN1), defined by global methylation patterns and strongly associated with gene fusions targeting MN1. We have studied a unique case of astroblastoma arising in a 6 year old girl, with multiple recurrences over a period of 10 years, with the pathognomonic MN1:BEND2 fusion. Exome sequencing allowed for a phylogenetic reconstruction of tumour evolution, which when integrated with clinical, pathological and radiological data provide for a thorough understanding of disease progression, with initial treatment driving tumour dissemination along four distinct trajectories. Infiltration of distant sites was associated with a later genome doubling, whilst there was evidence of convergent evolution of different lesions acquiring distinct alterations targeting NF-κB. These data represent an usual opportunity to understand the evolutionary history of a highly recurrent childhood brain tumour, and provide novel therapeutic targets for astroblastoma / CNS HGNET-MN1.

  Study EGAS00001002432

• Whole exome sequencing in patients with ALS and concomitant FTD lacking the C9orf72 repeat expansion

  Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are part of a clinical, pathological and genetic continuum. The purpose of the present study was to assess the mutation burden that is present in ALS and/or FTD known disease-causing genes in 54 patients (16 with available postmortem neuropathological diagnosis) with concurrent ALS and FTD (ALS/FTD) not-carrying the C9orf72 hexanucleotide repeat expansion, the most important genetic cause in both diseases.

  Study EGAS00001002439

• Biallelic mutations in the ubiquitin ligase RFWD3 cause Fanconi anemia

  The WD40-containing E3 ubiquitin ligase RFWD3 has been recently linked to the repair of DNA damage by Homologous Recombination (HR). Here we show that an RFWD3 mutation within the WD40 domain is connected to the genetic disease Fanconi anemia (FA). An individual revealed congenital abnormalities characteristic for FA. Cells from the patient, carrying the compound heterozygous mutations c.205_206dupCC and c.1916T>A in RFWD3, show increased sensitivity to DNA interstrand cross-linking agents in terms of increased chromosomal breakage, reduced survival and cell cycle arrest in G2 phase. The cellular phenotype is mirrored in genetically engineered human and avian cells by inactivation of RFWD3 or by introduction of the patient-derived missense mutation, and is rescued by expression of wildtype RFWD3 protein. HR is disrupted in RFWD3 mutant cells, caused by impaired relocation of mutant RFWD3 to chromatin and defective physical interaction with RPA. Rfwd3 knockout mice exhibit increased embryonic lethality, are sub-fertile, show ovarian and testicular atrophy and have a reduced life span in which they resemble other FA mouse models. Although mutation was detected in a single child with FA yet, we propose RFWD3 as a novel FA gene, FANCW, supported by cellular paradigm systems and an animal model.

  Study EGAS00001002440

• Clonal evolution and clinical implications of genetic abnormalities in blastic transformation of chronic myeloid leukaemia

  Blast crisis (BC) predicts dismal outcomes in patients with chronic myeloid leukaemia (CML). We comprehensively investigated genetic abnormalities in 136 BC and 148 chronic phase (CP) samples obtained from 216 CML patients using exome and targeted sequencing.

  Study EGAS00001005075

• Comprehensive Molecular Analysis of Colon Cancer for the Identification and Validation of New Biomarkers

  This study aims to identify diagnostic and prognostic biomarkers in colon cancer and to study understand the complex genomic, genetic and epigenetic relationships with a multiomic approach. The study includes tumor and paired normal mucosa of 100 colon cancer patients diagnosed at stage II, untreated and with microsatellite stable tumours. Also 50 normal mucosa samples from healthy donors are included as reference. The samples have been analysed for gene expression with Affymetrix U219 array (available at GEO GSE44076), SNP/CNV with the Affymetrix 6.0 Human SNP array, for DNA methylation with the Illumina 450K array. Small RNAs were sequenced with the Solid technology and 42 of the tumours and paired normal mucosa DNA were whole exome sequenced with Illumina Genome Analyzer.

  Study EGAS00001002453

• The demographic history and mutational load of African hunter-gatherers and farmers

  The distribution of deleterious genetic variation across human populations is a key issue in evolutionary biology and medical genetics. However, the impact of different modes of subsistence on recent changes in population size, patterns of gene flow, and deleterious mutational load remains unclear. Here, we report high-coverage exomes from various populations of rainforest hunter-gatherers and farmers from central Africa. We find that the recent demographic histories of hunter-gatherers and farmers differed considerably, with population collapses for hunter-gatherers and expansions for farmers, accompanied by increased gene flow. We show that purifying selection against newly arising deleterious alleles is of similar efficiency across African populations, in contrast with Europeans where we detect weaker purifying selection. Furthermore, the per-individual mutation load of rainforest hunter-gatherers is similar to that of farmers, under both additive and recessive models. Our results indicate that differences in the cultural practices and demographic regimes of African populations have not resulted in large differences in mutational burden, and highlight the beneficial role of gene flow in reshaping the distribution of deleterious genetic variation across human populations.

  Study EGAS00001002457

• ATRX mutant neuroblastoma is sensitive to EZH2 inhibition via modulation of neuronal differentiation.

  Mutations and structural alterations of the SWI/SNF-like chromatin remodeler ATRX have been reported at high frequency in a number of adult and pediatric tumors1. However, the consequences of ATRX (Alpha Thalassemia/Mental Retardation, X-linked) mutations in cancer and their underlying epigenetic sensitivities remain ill defined. Particularly intriguing are the large N-terminal deletions of ATRX in neuroblastoma that generate in-frame fusion (IFF) proteins1–3 devoid of key chromatin interaction domains. Here we demonstrate that neuroblastoma cells harbouring ATRX IFFs have distinct gene expression programs compared to neuroblastoma cells that are wild type for ATRX. This is due in part to H3K27me3-mediated silencing of REST (RE1 Silencing Transcription Factor) target genes involved in neuronal differentiation. In turn, we find that ATRX IFF cells display exquisite sensitivity to EZH2 inhibition in both adherent and tumorsphere conditions, due in part to derepression of neurogenesis genes, including REST targets. Examination of the epigenomic landscape of a pediatric neuroblastoma tumor harboring an ATRX IFF revealed that H3K27me3 occupies a subset of REST target genes that are transcriptionally silenced, and are sensitive to EZH2 inhibition in our cell-based assays. Thus, our study greatly advances our understanding of indolent neuroblastoma and identifies EZH2 inhibition as a potential therapy for patients with ATRX mutant disease. Further, these studies may be applicable to other ATRX mutant pediatric malignancies, particularly those carrying similar structural alterations of ATRX.

  Study EGAS00001002507

• Genomic and epigenomic characterization of juvenile myelomonocytic leukemia (JMML)

  Juvenile myelomonocytic leukemia (JMML) is an aggressive myeloproliferative disorder of early childhood. While some cases show spontaneous remission, allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative treatment option for the majority of patients, however, the 5-year event-free survival reaches only about 50%. Hyperactive RAS signaling is assumed to be the main driving event in JMML. It is caused by genetic alterations in CBL, KRAS, NF1, NRAS, or PTPN11 in about 90% of patients. So far, there is no clear understanding of how RAS pathway mutations relate to the heterogeneous disease biology and variable clinical outcome seen in JMML patients. As a consequence, established clinical and genetic markers fail to fully represent the observed disease heterogeneity. We hypothesized that DNA methylation profiling, either alone or in combination with genetic alterations, might provide a molecular basis for disease classification. Genome wide DNA methylation analysis using the HumanMethylation450 Bead Chip array was performed in a discovery cohort of 20 patients (19 JMML, 1 Noonan syndrome). The clinical relevance of our findings was assessed in an unselected sample set consisting of 147 consecutive patients with JMML (n=129) or Noonan syndrome (n=18) associated myeloproliferative disorder (n=18) registered in the EWOG-MDS 1998 & 2006 trials. Data integration was performed in a subset of patients with available exome sequencing (n=50) and expression profiling (n=15) data. This integrated approach identified three JMML subgroups characterized by distinct clinical and biological features. This analysis further suggested a molecular mechanism by which additional genetic events, presumably further activating the RAS-RAF-MEK-ERK pathway, mediate DNA hypermethylation via up-regulation of DNMTs in more aggressive JMML cases.

  Study EGAS00001002511

• Sampling of multi-centric lower grade glioma influences management and provides insight into gliomagenesis

  Rare multicentric lower-grade gliomas (LGG) represent a unique opportunity to study the heterogeneity between distinct tumor foci in a single patient, and to infer their origins and parallel patterns of evolution. In this study, we integrate clinical features, histology and immunohistochemistry for 4 patients with multicentric LGG, arising both synchronously and metachronously. For 3 patients we analyze the phylogeny of the lesions using exome sequencing, including one case with a total of 8 samples from the two lesions. We show that each tumor in multicentric LGG cases may arise independently or may diverge very early in their development, presenting as genetically and histologically distinct tumors suggesting that comprehensive sampling of these lesions can significantly alter diagnosis and management.

  Study EGAS00001002495