Search Results - EGA European Genome-Phenome Archive

Single_Cell_Sequencing_of_Sperm__scSperm_

The aim of this project is to genotype and sequence single spermatozoa from two men, one in his twenties and the other in his seventies. The resulting data is used to quantify the mutations that have arisen in the gametes of both individuals in order to better understand the effect of aging on mutation rates and modes.Project Outline. In order to quantify mutations, semen from two individuals are sequenced. 48 single sperm cells are isolated from each individual, and their DNA is extracted. The resulting genomes are amplified using PicoPlex, GenomiPhi MDA, Repli-G MDA, and MALBAC. QC step is applied to check the quality of WGA DNA using standard Sequenom plex (26 SNPs). A subset of 32 amplification products which pass the intiall QC, are genotyped using Affymetrix SNP6 chips. 12 of the genotyped amplification products are also sequenced. In addition, one multi-cell sample per individual is sequenced as a reference and for validation purposes.Altogether, 12 single cell sperm genomes and two multi-cell genomes are sequenced, coming to a total of 14 genomes. Of the single cell sperm genomes, 2 are sequenced to 50x coverage, and the other 10 to 25x coverage. Both multi-cell genomes are sequenced to 25x coverage.

Study EGAS00001000935

The Genomic Landscape of Core-Binding Factor Acute Myeloid Leukemias

Pediatric de novo acute myeloid leukemia (AML) is a heterogeneous disease that can be divided into clinically distinct subtypes based on the presence of specific chromosomal abnormalities or gene alterations. One of the best characterized subtypes of AML involves leukemias with alterations of the core-binding factor (CBF)-complex, which comprises the FAB subtypes M2 and M4Eo and associates with a favorable outcome. Patients with the AML M2 subtype harbor a translocation between chromosomes 8 and 21 [t(8;21)] that yields the chimeric fusion gene RUNX1(AML1)-RUNX1T1(ETO), while patients with AML M4Eo express the chimeric fusion gene CBFβ-SMMHC(MYH11) as a result of an inversion/translocation event of chromosome 16 [inv(16)/t(16;16)]. In an effort to define the total complement of genetic changes in CBF-leukemia, we performed paired-end whole genome sequencing (WGS) on diagnostic leukemia blasts and matched germ line samples from 17 pediatric CBF-leukemia patients using the Illumina platform. Somatic alterations, including single nucleotide variations (SNVs) and structural variations (SVs), including insertions, deletions, inversions, and inter- and intra-chromosomal rearrangements, were detected using complementary analysis pipelines (Bambino, CREST and CONSERTING). Recurrent screening of identified mutations will be performed in a cohort of approximately 94 cases of CBF-leukemias.

Study EGAS00001000349

ERG ALTERATIONS DEFINE A NOVEL SUBTYPE OF ACUTE LYMPHOBLASTIC LEUKEMIA

Structural chromosomal alterations are a hallmark of acute lymphoblastic leukemia (ALL) yet many patients lack an identifiable abnormality on conventional cytogenetic analysis. Here, using integrated analysis of genome-wide DNA copy number and gene expression data of 1764 childhood and adult ALL cases, including whole-genome, exome and mRNA-sequencing of 72 cases, we report a novel subtype of B-progenitor ALL (B-ALL) representing 4-13% of B-ALL cases characterized by a distinct gene expression profile, and focal deletions of ERG (ETS related gene) in 56% of cases. These cases are characterized by expression of a ERG transcript that utilizes a novel exon in intron 6 of ERG spliced to the canonical reading frame of ERG exons 7-10, encoding a 27 kDa C-terminal ERG protein that retains the ETS and transactivating domains but lacks the N-terminal pointed and regulatory domains. This protein is a competitive inhibitor of wild-type ERG and is leukemogenic in vivo. ERG-altered ALL cases have a favourable outcome despite the presence of alterations associated with poor prognosis in non-ERG ALL, such as deletions of IKZF1. These findings identify a new subtype of leukemia characterized by a novel mechanism of ETS transcription factor dysregulation in cancer.

Study EGAS00001000514

An RCOR1 loss-associated gene expression signature identifies a prognostically significant DLBCL subgroup

Effective treatment of diffuse large B cell lymphoma (DLBCL) is plagued by heterogeneous responses to standard therapy, and molecular mechanisms underlying unfavorable outcomes in lymphoma patients remain elusive. Here, we profiled 148 genomes with 91 matching transcriptomes in an R-CHOP-treated DLBCL cohort to uncover molecular subgroups linked to treatment failure. Systematic integration of high-resolution genotyping arrays and RNA-seq data revealed novel deletions in RCOR1 to be associated with unfavorable progression free survival (P = 0.001). Integration of expression data from the clinical samples with data from RCOR1 knockdowns in the lymphoma cell lines KM-H2 and Raji yielded an RCOR1 loss-associated gene signature comprising of 233 genes. This signature identified a subgroup of patients with unfavorable overall survival (OS) (P = 0.023). The prognostic significance of the 233-gene signature for OS was reproduced in an independent cohort comprising of 195 R- CHOP treated patients (P = 0.039). Additionally, we discovered that within the IPI low risk group, the gene signature provides additional prognostic value that was independent of the cell-of-origin phenotype. Taken together, we present a novel and reproducible molecular subgroup of DLBCL, impacting risk-stratification of R- CHOP treated DLBCL patients and revealing a new avenue for therapeutic intervention strategies.

Study EGAS00001001000

Accurate sample assignment in a multiplexed, ultra-sensitive, high-throughput sequencing assay for minimal residual disease

High throughput sequencing (HTS) (next generation sequencing) of the rearranged immunoglobulin and T-cell receptor genes promises to be cheaper and more sensitive than current methods for monitoring minimal residual disease (MRD) in patients with acute lymphoblastic leukemia. However, adoption of new approaches by clinical laboratories requires careful evaluation of all potential sources of error and the development of strategies to ensure the highest accuracy. Timely and efficient clinical use of HTS platforms will depend on combining multiple samples (multiplexing) in each sequencing run. Here we examine immunoglobulin heavy chain gene HTS on the Illumina MiSeq platform for MRD (HTS-MRD). We identify errors associated with multiplexing that could potentially impact on the accuracy of MRD analysis. We optimise a strategy combining high purity, sequence-optimised oligonucleotides, dual-indexing and an error-aware demultiplexing approach to minimise errors and maximise sensitivity. We present a probability-based demultiplexing pipeline, Error-Aware Demultiplexer (EAD) - that is suitable for all MiSeq sequencing strategies and accurately assigns samples to the correct identifier without excessive loss of data. Finally using controls quantified by digital PCR, we show that HTS-MRD can accurately detect as few as 1 in 106 copies of specific leukemic MRD.

Study EGAS00001001303

Rare SNPs in receptor tyrosine kinases are negative outcome predictors in multiple myeloma

Multiple myeloma (MM) is a plasma cell disorder that is characterized by a great genetic heterogeneity. Recent next generation sequencing studies revealed an accumulation of tumor-associated mutations in receptor tyrosine kinases (RTKs) which may also contribute to the activation of survival pathways in MM. To investigate the clinical role of RTK-mutations in MM, we deep-sequenced the coding DNA-sequence of EGFR, EPHA2, ERBB3, IGF1R, NTRK1 and NTRK2 which were previously found to be mutated in MM, in 75 uniformly treated MM patients of the "Deutsche Studiengruppe Multiples Myelom". Subsequently, we correlated the detected mutations with common cytogenetic alterations and clinical parameters. We identified 11 novel non-synonymous SNVs or rare patient-specific SNPs, not listed in the SNP databases 1000 genomes and dbSNP, in 10 primary MM cases. The mutations predominantly affected the tyrosine-kinase and ligand-binding domains and no correlation with cytogenetic parameters was found. Interestingly, however, patients with RTK-mutations, specifically those with rare patient-specific SNPs, showed a significant lower overall, event-free and progression-free survival. This indicates that RTK SNVs and rare patient-specific RTK SNPs are of prognostic relevance and suggests that MM patients with RTK-mutations could potentially profit from treatment with RTK-inhibitors.

Study EGAS00001001665

Recurrent somatic JAK-STAT mutations within a novel RUNX1-mutated pedigree

The acquisition of somatic mutations is an emerging field of investigation in familial leukemia. Currently, genetic profiles in familial MDS/AML are considered analogous to sporadic disease, although the patterns of clonal evolution within families are poorly defined. We performed whole exome profiling of tumour samples from a novel RUNX1 mutated family, to determine the stepwise evolution of MDS/AML across 4 young siblings. Three siblings developed monocytic AML/RAEB2 at 5 years of age, with hepatosplenomegaly and somatic mutations upregulating JAK-STAT signalling, the latter are typically detected in <5% of sporadic MDS/AML. Two siblings acquired the canonical JAK2 V617F mutation, while another acquired a unique missense mutation of SH2B3, a negative regulator of JAK2. Notably, 2/3 siblings demonstrated dosage amplification of these mutations due to acquired uniparental disomy of chromosomes 9p and 12q (encompassing JAK2 and SH2B3, respectively). All 4 siblings were heterozygous for the 46/1 JAK2 haplotype associated with predisposition to sporadic V617F myeloproliferative disorders, which likely influenced the acquisition of JAK2 mutations. Our findings provide further evidence that relatives with shared germline mutations may acquire somatic mutations in a non-random manner leading to convergent patterns of disease evolution.

Study EGAS00001001862

Genomics of enteropathy associated T cell lymphoma (EATL)

Enteropathy-associated T cell lymphoma (EATL) is a lethal and the most common neoplastic complication of celiac disease. In this study, we applied whole exome sequencing in 69 EATL tumors to define the genetic landscape of EATLs. The most frequently mutated gene in EATL was SETD2 (32% of cases), with loss of function mutations comprising a large proportion (41%) of those mutations. The JAK-STAT pathway was the most frequently mutated signaling pathway, with mutations in STAT5B being the most common, followed by JAK1, JAK3, STAT3, and the negative regulator of the pathway, SOCS1. We also identified mutations in NRAS and KRAS, as well as TP53 and TERT. Interestingly, the two types of EATL had highly overlapping genetic alterations indicating shared mechanisms underlying their pathogenesis. Gene expression analysis of the two types of EATL identify robust differences in transcriptional profiles. We further modeled the effects of SETD2 loss in vivo by developing a T cell specific knockout mouse model. These mice manifested an expansion of γδ T cells that identify novel roles for SETD2 in T cell development and lymphomagenesis. Together, our data render the most comprehensive genetic portrait yet of this uncommon but lethal disease, and may inform future classification schemes.

Study EGAS00001001954

Whole genome sequencing of tumour and normal paired samples of diffuse intrinsic pontine gliomas

Diffuse intrinsic pontine glioma (DIPG) have a universally dismal prognosis (median 9-12 months), with neither chemotherapeutic nor targeted agents showing any substantial survival benefit in clinical trials in children with these tumours. DIPG are highly infiltrative malignant glial neoplasms of the ventral pons, which due to their location within the brain, make them unsuitable for surgical resection and consequently have a universally dismal clinical outcome. Recent high-throughput sequencing approaches have revealed a striking prevalence of K27M mutations in the genes encoding the histone variants H3.3 (H3F3A) or H3.1 (HIST1H3B) in the childhood brain tumour DIPG. This K-to-M substitution confers a trans-dominant ablation of global H3K27 trimethylation, which likely profoundly alters gene expression through de-repression of polycomb repressive complex 2 (PRC2) target genes. Despite these advances in our understanding of the distinct biology of these tumours, approaches for specific novel therapeutic interventions are not clear, and little has been reported of the secondary mutations accompanying these changes. We carried out whole genome sequencing on a series of 20 tumour normal pairs of pre-treatment biopsy samples of DIPG, for which the patients underwent a safe stereotactic procedure, and whole exome sequencing on a further six tumour normal pairs obtained at autopsy.

Study EGAS00001000572

Pediatric Non-Down Syndrome Acute Megakaryoblastic Leukemia is Characterized by Distinct Genomic Subsets with Varying Outcomes

Acute Megakaryoblastic Leukemia (AMKL) is a subtype of acute myeloid leukemia (AML) in which cells morphologically resemble abnormal megakaryoblasts. While extremely rare in adults, AMKL accounts for 4-15% of newly diagnosed childhood AML1-3. A significant proportion of pediatric AMKL cases occur in children with Down syndrome (DS). These patients have excellent outcomes and are characterized at the genomic level by a founding GATA1 mutation4-6. In contrast, AMKL in patients without DS (non-DS-AMKL) is frequently associated with poor outcomes. Previous efforts have identified chimeric oncogenes in a significant number of cases, including RBM15-MKL1, CBFA2T3-GLIS2, KMT2A gene rearrangements and NUP98-KDM5A7-9. The etiology of 30-40% of cases, however, remains unknown. To better understand the genomic landscape of non-DS-AMKL, we performed RNA and exome sequencing on specimens from 99 patients (75 pediatric and 24 adult). We demonstrate that pediatric non-DS-AMKL is a heterogeneous malignancy that can be divided into seven subgroups with varying outcomes. These subgroups are characterized by chimeric oncogenes with cooperating mutations in epigenetic and kinase signaling genes. Overall, these data shed light on the etiology of AMKL and provide useful information for treatment tailoring.

Study EGAS00001002183

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