Search Results - EGA European Genome-Phenome Archive

Comparison of 3 protocols for deriving pancreatic progenitors from hPSC with RNA-seq and ATAC-seq

Several distinct differentiation protocols for deriving pancreatic progenitors (PP) from human pluripotent stem cells have been described but it remains to be shown how similar the PP are across protocols, and how well they resemble their in vivo counterparts. Here we evaluated three differentiation protocols; performed RNA and ATAC-seq on isolated PP derived with these, and compared them to fetal human pancreas populations. This enabled us to define a shared transcriptional and epigenomic signature of the PP, including several genes not previously implicated in pancreas development. Furthermore, we identified a significant and previously unappreciated cross-protocol variation of the PP through multi-omics analysis and demonstrate how such information can be applied to refine differentiation protocols for derivation of insulin-producing beta-like cells. Together, our study highlights the importance of a detailed characterization of defined cell populations derived from distinct differentiation protocols, and provides a valuable resource for exploring human pancreatic development.

Study EGAS00001003513

A molecular signature for IL-10-producing Th1 cells in protozoan parasitic diseases

Control of the intracellular parasites that cause malaria and visceral leishmaniasis (VL) is dependent on the generation of pro-inflammatory, IFNγ+ Tbet+ CD4+ T (Th1) cells by infected hosts. Immunoregulatory IL-10 produced by Th1 cells serves to mitigate subsequent inflammation and related disease pathology. However, these IL-10-producing Th1 (Tr1) cells can also not only promote parasite persistence, but may impair immunity to re-infection and potential vaccine efficacy. Here, we identify molecular and phenotypic signatures that distinguish Th1 cells from Tr1 cells in both experimental VL, caused by infection of C57BL/6 mice with the human parasite Leishmania donovani, and in Plasmodium falciparum-infected humans participating in controlled human malaria infection (CHMI) studies. Such characterisations allow for the better understanding of Tr1 cell development and function in the context of these parasitic diseases, and for the identification of targets for immune modulation to improve anti-parasitic immunity.

Study EGAS00001004454

Full genome sequencing of a monozygotic twin discordant for schizophrenia

We sequenced the genomes from a monozygotic twin discordant for schizophrenia and a tumor-normal pair of an ovarian cancer patient. Using whole-genome twin data to discriminate between correctly identified single nucleotide variants (SNVs) and errors a strategy for the accurate detection of SNVs was developed. By applying stringent sequencing quality measures, excluding error-prone regions and selecting SNVs identified by different mapping and variation calling algorithms, error rates were ~37-fold reduced. This enabled us to identify the first discordant SNVs in monozygotic twins using whole-genome sequencing. In addition, by showing that novel SNVs are highly enriched in errors, accurate estimates of the number of novel and rare SNVs occurring in unrelated Caucasian individuals were obtained. Finally, somatic mutations in coding and regulatory sequences were reliably identified in the highly rearranged ovarian tumor. Overall, our data demonstrate that strategies to reduce error rates in whole-genomes are required for disease gene discovery.

Study EGAS00001000152

Institut Curie Neuroblastoma Whole Genome Sequencing Diagnosis Relapse

Neuroblastoma, a clinically heterogeneous pediatric cancer, is characterized by distinct genomic profiles but few recurrent mutations. As neuroblastoma is expected to have high degree of genetic heterogeneity, study of neuroblastoma's clonal evolution with deep coverage whole-genome sequencing of diagnosis and relapse samples will lead to a better understanding of the molecular events associated with relapse. Samples were included in this study if sufficient DNA from constitutional, diagnosis and relapse tumors was available for WGS. Whole genome sequencing was performed on trios (constitutional, diagnose and relapse DNA) from eight patients using Illumina Hi-seq2500 leading to paired-ends (PE) 90x90 for 6 of them and 100x100 for two. Expected coverage for sample NB0175 100x100bp was 30X for tumor and constitutional samples. For the seven other patients expected coverage was 80X for tumor samples with PE 100x100, 100X in the other tumor samples and 50X for all constitutional samples (see table 1). Following alignment with BWA (Li et al., Oxford J, 2009 Jul) allowing up to 4% of mismatches, bam files were cleaned up according to the Genome Analysis Toolkit (GATK) recommendations (Van der Auwera et al., Current Protocols in Bioinformatics, 2013, picard-1.45, GenomeAnalysisTK-2.2-16). Variant calling was performed in parallel using 3 variant callers: GenomeAnalysisTK-2.2-16, Samtools-0.1.18 and MuTect-1.1.4 (McKenna et al., Genome Res, 2010; Li et al., Oxford J, 2009 Aug; Cibulskis et al., Nature, 2013). Annovar-v2012-10-23 with cosmic-v64 and dbsnp-v137 were used for the annotation and RefSeq for the structural annotation. For GATK and Samtools, single nucleotide variants (SNVs) with a quality under 30, a depth of coverage under 6 or with less than 2 reads supporting the variant were filter out. MuTect with parameters following GATK and Samtools thresholds have been used to filter our irrelevant variants. .SNVs within and around exons of coding genes overlapping splice sites.. Then,variants reported in more than 1% of the population in the 1000 genomes (1000gAprl_2012) or Exome Sequencing Project (ESP6500) have been discarded in order to filter polymorphisms. Finally, synonymous variants were filtered out. MuTect focuses on somatic by filtering with constitutional sample. Mpileup comparison between constitutional and somatic DNAs allowed us to focus also on tumor specific SNVs with GATK and Samtools. Finally, every SNV called by our pipeline and also supported in any constitutional samples were filtered our in order to prevent putative constitutional DNA coverage deficiency. Then we analyzed CNVs (copy number variants) with HMMcopy-v0.1.1 (Gavin et al., Genome Res, 2012) and control-FREEC-v6.7 (Boeva et al., Bioinformatics 2011) with a respective window of 2000bp and 1000 bp, and auto-correction of normal contamination of tumor samples for Control-FREEC. Finally we explored Structural variants (SVs) including deletions, inversions, tandem duplications and translocations using DELLY-v0.5.5 with standard parameters (Rausch et al., Oxford J, 2012). In tumors, at least 10 supporting reads were required to make a call and 5 supporting reads for the sample NB0175 with a coverage of only 40X (see table 2). To predict SVs in constitutional samples for subsequent somatic filtering, only 2 supporting reads were required in order not to miss one. To identify somatic events, all the SVs in each normal sample were first flanked by 500 bp in both directions and any SVs called in a tumor sample which was in the combined flanked regions of respective normal sample was removed (see graph 1). Deletions with more than 5 genes impacted or larger than 1Mb and inversions or tandem duplications covering more than 4 genes, were removed. We focused on exonic and splicing events for deletions, inversions, and tandem duplications. For translocation, we keep all SVs that occurred in intronic, exonic, 5'UTR, upstream or splicing regions. Bioinformatics detection of variations with Deep sequencing approach Once PE reads merged and adaptors trimmed by SeqPrep with default parameters, merged reads were aligned via the BWA (Li H. and Durbin R. 2009 PMID 19451168) allowing up to 1 differences in the 22-base-long seeds and reporting only unique alignments. Only reads having a mapping quality 20 or more have been further analysed. Variant calling software was not used, since we aimed to predict variations at low frequencies, observed in less than 1% of reads. Such variants require a custom approach. Using DepthOfCoverage functions of the Genome Analysis Toolkit (GATK) v2.13.2 (McKenna A, et al., 2010 Genome Research PMID: 20644199), we focused on high quality coverage of bases A, C, G and T at the targeted variant position. Depth of coverage of each base following a mapping quality higher than 20 and a base quality higher than 10 have been taken into account in order to focus only on high quality data. Aiming to determine the background level of variability at the studied regions, 10 control samples were included in the analysis. The same approach and filtering criteria have been applied as introduced above over the entire amplicons. In order to highlight variants, for each sample the frequencies of each bases at each amplicon position were then compared to those observed in the set of controls. Statistical analyses were performed with the R statistical software (http://www.R-project.org). Fisher’s exact two-sided tests with a Bonferroni correction were performed to compare percentages of bases between the data sets, i.e. for a given base between a case and the controls. Finally, significant variations were filtered-in once (i) a significant increase in the percentage of avariant base and (ii) a significant decrease in the percentage of it's reference base following our p.values criteria was observed (p.val < 0.05).

Study EGAS00001001184

International Consortium on the Genetics of Systemic Lupus Erythematosus (SLEGEN)

The genetic makeup of an individual strongly influences the risk of developing systemic lupus erythematosus (SLE). The identification of genes that predispose an individual to SLE will lead to earlier and better diagnosis, better treatments, and possibly prevention. To this end, the International Consortium on the Genetics of Systemic Lupus Erythematosus (SLEGEN) was formed in 2005 and is composed of lupus researchers who agreed to pool their knowledge and resources to search for genes that predispose to lupus. Eight laboratories contributed DNA samples for genotyping at the Broad Institute and association with SLE was performed by the Data Coordinating Center (Wake Forest University), as part of a four stage study design. Stages one and two of this design were graciously funded by the Alliance for Lupus Research (www.lupusresearch.org). In this stage of the study, approximately 767 SLE patients (cases) were compared to approximately 383 non-SLE patients (controls) for differences among the Illumina HumanHap300. The affected individuals are all females of European decent. 82% of the cases are the index case from multiplex pedigrees for SLE and the remaining 18% have self-reported first degree relatives with SLE. A detailed summary of the methods and results can be found in the manuscript in Nature Genetics February 2008 by SLEGEN "Genome-wide association scan in women with systemic lupus erythematosus identifies susceptibility variants ITGAM, PXK, KIAA1542 and other loci". (Please see also Study Accession: phs000202.v1.p1)

Study phs000216

Biomarkers in Transplant Recipients

Biliary atresia causes jaundice and liver failure in newborn children. In this study, single nucleotide polymorphisms were characterized in children with biliary atresia and identified ARF6 as a susceptibility gene for this disease. Knockdown of this gene in zebrafish embryos impaired formation of bile ducts and excretion of bile from the zebrafish liver. Subject enrollment: Children with biliary atresia were enrolled at Children's Hospital of Pittsburgh (CHP) after obtaining written consent from parents for the University of Pittsburgh IRB approved protocol number 0405628. At the Center for Applied Genomics (CAG), all subjects were enrolled after obtaining written consent from parents per Children's Hospital of Philadelphia IRB approval number 06-004886 Genotyping array: Genotyping of DNA obtained from blood was performed with the Infinium HumanHap550K BeadChip (Illumina, San Diego, CA). Statistical methods and software: SNP genotype frequencies were compared between cases and controls with a chi-square test statistic applied in Plink [Purcell et al, 2007] for SNPs with at least 90% call rate and 1% minor allele frequency (MAF). Cases and controls: All DNA samples had excellent data quality with call rates > 98%. A total of 63 Caucasian BA cases and 1907 controls were compared at > 550000 SNPs, and demonstrated a very low genomic inflation factor of 1.00627. Description of Cases: Biliary atresia patients had received a Kasai procedure and demonstrated histopathological features of biliary obstruction, and were recruited at evaluation for transplantation or after liver transplantation.

Study phs000960

A Phase I/II Study of Revlimid (lenalidomide) in Combination with Vidaza (azacitidine) in Patients with Advanced Myelodysplastic Syndrome (MDS)

This single-arm study design has been selected to investigate the safety of combination therapy with Vidaza® (azacitidine) and Revlimid® (lenalidomide) in a population of 18 participants with advanced MDS for the Phase I portion, and 18 participants for the Phase II portion. The multi-center nature of the study should enhance the general applicability of the results. Participants with advanced MDS were chosen because it is expected that the combination of the two drugs will by myelosuppressive, which can be considered a necessary toxicity to effect improvements in PR and CR rates in this advanced population, akin to participants with AML. Finally, the combination was chosen to be studied because currently available therapies in this population, and their effectiveness, are limited, and single-agent Vidaza® (azacitidine), while effective at delaying transformation to AML or death, is not curative. The doses of Revlimid® (lenalidomide) in this study are similar to those that were demonstrated to have an effect and to be well-tolerated in participants with MDS. Doses for Vidaza® (azacitidine) are similar to those used in the pivotal trial, though for a 5-day treatment period instead of 7 to minimize toxicity for the first 3 blocks of participants, and then at a lower dose over a protracted period of time to explore the safety of a 10-day treatment course.

Study phs001318

Genomic Architecture of Progression and Treatment Response in AMD

Numerous studies have identified common and rare genetic variation associated with risk of advanced age-related macular degeneration (AMD). However, risk is just one facet of AMD disease architecture. Both disease progression and response to treatment are two critical elements that may also be influenced by genetic variation. The primary aim of this study was to identify genetic variation influencing progression and response to treatment for AMD, with a secondary aim of further elucidating the genetic etiology of AMD risk. We ascertained AMD cases and controls of European ancestry from Vanderbilt Eye Institute (VEI) and the Bascom Palmer Eye Institute (BPEI) and obtained blood samples from all participants. Eyes were examined using standard ophthalmological methods, and graded according the modified Age-Related Eye Disease Study scale (AREDS grades 1-5) using fundus photography. Individuals were re-examined in follow-up exams at regular intervals to assess any change in AMD grade. Eyes with advanced neovascular AMD that were examined using ocular coherence tomography imaging (OCT), treated with anti-angiogenesis therapy and monitored for response to treatment. All individuals ascertained for the study were exome-chipped for genome-wide single nucleotide variation coverage. To target rare genetic variation, whole exome sequencing was performed on individuals at the phenotypic extremes based on 1) AMD grade, 2) rate of progression from intermediate to advanced AMD and 3) response to anti-VEGF treatment for eyes with advanced neovascular AMD.

Study phs001046

University of Texas PDX Development and Trial Center Grant

The goal for the University Texas PDX Development and Trial Center (UTPDTC) is to optimize personalized biomarker-based cancer therapy and identify effective targeted drugs based on the molecular characteristics of each tumor. Our short-term goals are to establish a biobank of clinically, and molecularly-annotated Patient-Derived Xenografts (PDXs) and to use PDXs as a platform for preclinical drug development and biomarker discovery. The primary goal for UTPDTC investigators will be to develop PDX trial strategies for preclinical testing of single agents and drug combinations. These models will allow the determination of the optimal treatments (single drugs or combinations) that should be tested in clinical trials in increasingly individualized, molecularly defined subsets of tumors. The goal of the Patient-Derived Xenograft Core is to provide high-quality clinically relevant and molecularly annotated PDX models for the research projects proposed in the University of Texas PDX Development and Trial Center (UTPDTC) grant application and to the research activity of the NCI PDX Development and Trial Centers Research Network (PDXNet) by leveraging PDX resources at our institutions and developing new PDX models from human cancer specimens using rigorous quality standards so that the models can be used to guide clinical trial development. The PDX models developed and/or characterized by the PDX Core will be available to other cancer researchers through the PDXNet and NCI Patient-Derived Models Repository (PDMR).

Study phs001980

Evolution of the African pygmy phenotype

The evolutionary history of the human ‘pygmy’ phenotype (small body size), a characteristic of African and Southeast Asian rainforest hunter-gatherers, is largely unknown. Here we use a genome-wide admixture mapping analysis to identify 16 genomic regions that are significantly associated with the pygmy phenotype in the Batwa, a rainforest hunter-gatherer population from Uganda (East Central Africa). The identified genomic regions have multiple attributes that provide supporting evidence of genuine association with the pygmy phenotype, including enrichments for SNPs previously associated with stature variation in Europeans and for genes with growth hormone receptor and regulation functions. To test adaptive evolutionary hypotheses we computed the haplotype-based iHS statistic and the level of population differentiation (FST) between the Batwa and their agricultural neighbors, the Bakiga, for each SNP. Both |iHS| and FST values were significantly higher for SNPs within the Batwa pygmy phenotype-associated regions than the remainder of the genome, a signature of polygenic adaptation. In contrast, when we expanded our analysis to include Baka rainforest hunter-gatherers from Cameroon and Gabon (West Central Africa) and Nzebi and Nzime neighboring agriculturalists, we did not observe elevated |iHS| or FST values in these genomic regions. Together, these results suggest adaptive and at least partially convergent origins of the pygmy phenotype even within Africa, supporting the hypothesis that small body size confers a selective advantage for tropical rainforest hunter-gatherers but raising questions about the antiquity of this behavior.

Study EGAS00001000908

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