Search Results - EGA European Genome-Phenome Archive

Epigenomics of Patient Outcomes after Aneurysmal SAH

This project was focused on understanding the pathophysiology following aneurysmal subarachnoid hemorrhage (aSAH). DNA methylation is a key mechanism for regulation of gene expression and function in the adult brain and appears to play an important role in neuroprotection during ischemic events in the brain. Delayed cerebral ischemia (DCI), occurring during the acute phase following aSAH, is a major contributor to the complications that later develop; however, the pathophysiology of DCI and the development of complications is not known. We hypothesize that characterizing the methylome representing the CNS environment post aSAH will clarify the pathophysiology associated with DCI and patient outcomes. The aims of this project focused on the daily genome-wide methylomic changes that occur in DNA representing the CNS for the first 14 days after aSAH, as well as in peripheral blood in a subset of partcipants, and determining if this methylomic data impacts DCI and the development of complications after aSAH.

Study phs001990

Genomic Analysis of Paired Endometrial Cancer Primaries and Metastases

Formation of metastases is the major cause of cancer related deaths. Recent studies have sequenced primary endometrial carcinomas yielding data for a single entity in the progression from the birth of a progenitor tumor cell to metastatic disease. However, the progression of these tumors to metastases has not been characterized. We performed whole-exome sequencing of 98 tumor biopsies including complex atypical hyperplasias, primary tumors and paired abdominopelvic metastases to survey the evolutionary landscape of endometrial cancer. We expanded and reanalyzed TCGA-data, identifying novel recurrent alterations in primary tumors, including mutations in the estrogen receptor cofactor NRIP1 in 12% of patients. We found that likely driver events tended to be shared by primary and metastatic tissue-samples, with notable exceptions such as ARID1A mutations. Phylogenetic analyses in cases with multiple metastases indicated these metastases typically arose from one lineage of the primary tumor. These data indicate extensive genetic heterogeneity within endometrial cancers and relative homogeneity across metastatic sites.

Study phs001127

Genetic Studies in the Hutterites

We conducted genetic studies of disease-associated quantitative phenotypes, including microbiome and gene expression studies, and common diseases, such as asthma and Alzheimer's disease, by genotyping and/or sequencing in the Hutterites, a founder population of European descent. The Hutterites who have participated in our studies live on communal farms in South Dakota and are related to each other through multiple lines of descent in a 3,657-person, 13-generation pedigree with 64 founders. The small number of founding genomes reduces genetic heterogeneity whereas their communal lifestyle ensures that non-genetic factors are remarkably uniform between individuals. Our sample includes >1,600 subjects who have participated in our studies of fertility (since 1982), asthma, cardiovascular disease and other complex phenotypes (since 1993), microbiome studies (since 2011), and/or immune response (since 2012). The variable 'Total number of consented subjects' reflects the count of subjects with individual level phenotype and genotype data in dbGaP.

Study phs000185

Structurally Complex Osteosarcoma Genomes Exhibit Limited Heterogeneity within Individual Tumors and across Evolutionary Time

A key characteristic of osteosarcoma is extensive and complex genomic rearrangements. However, published models explaining how these genomic rearrangements occur disagree about if these rearrangements occur early in tumor progression and then are stable afterwards, or if there is ongoing genomic instability. Previous studies have employed bulk sequencing technologies to characterize genomic alterations. A limitation of this approach is that it averages all changes within the bulk sample, essentially masking intra-sample heterogeneity and making evaluation of ongoing genomic instability difficult. To overcome this limitation and compliment previous work, we utilized single-cell whole genome sequencing to quantify somatic copy number alterations (SCNA). By interrogating individual cells within a sample, we were able to examine intra-sample heterogeneity. We found that the SCNA patterns between cells within a single sample were remarkably consistent, which supports the concept that the genomes of osteosarcoma tumors are relatively stable after early genome fragmentation events.

Study phs003209

Metastatic Colorectal Adenocarcinoma Tumor Purity Assessment from Whole Exome Sequencing Data

As molecular medicine wields greater and greater influence on cancer patient care, including therapeutic selection, it becomes increasingly important to understand the power and deficiencies of computational tools used in decision making processes. Here we use a set of unselected metastatic colorectal tumor samples in a head-to-head comparison between the calculation of stromal content by a board certified pathologist, versus that derived from whole exome sequencing and purity assessment by a variety of common computational methods. We find that in about 1/2 of the samples the computational methods each do a poor job of assessing the percent stromal contamination, and as a result, tumor variant allele frequencies (VAFs) are low or undetected, whereas analysis of organoids derived from the same tumors yielded much higher VAFs in keeping with their lower stromal content. The whole exome sequence of our samples is available via dbGaP, accession phs003059.v1.p1.

Study phs003059

L1-Seq and Genome-Wide SNP Genotyping in a Multiethnic Asian Population

Insertions of the human-specific subfamily of LINE-1 (L1) retrotransposon are highly polymorphic across individuals and can critically influence the human transcriptome. We hypothesized that L1 insertions could represent genetic variants determining important human phenotypic traits, and performed an integrated analysis of L1 elements and single nucleotide polymorphisms (SNPs) in several human populations. We found that a large fraction of L1s were in high linkage disequilibrium (LD) with their surrounding genomic regions and that they were well-tagged by SNPs. However, L1 variants were only partially captured by SNPs on standard SNP arrays, so that their potential phenotypic impact would be frequently missed by SNP array-based genome-wide association studies. We next identified potential phenotypic effects of L1s by looking for signatures of natural selection linked to L1 insertions; significant extended haplotype homozygosity (EHH) was detected around several L1 insertions. This suggests that some of these L1 insertions may have been the target of recent positive selection.

Study phs000732

Genetic Analysis of Latin American Cervical Cancer

HPV16 is the most oncogenic type of human papillomaviruses (HPV). Integration of HPV into the human genome is an important mechanism of carcinogenesis but is absent in at least 30% of HPV16+ tumors. We applied long-read whole-genome sequencing (WGS) to cervical cancer cell lines and tumors to characterize HPV16 carcinogenesis in the absence of integration. WGS of HPV16+ cervical tumor samples from Latin America revealed that 11/20 tumors with only episomal HPV (EP) had intact monomer episomes. The remaining 9 EP tumors had multimer and rearranged HPV genomes. The majority (80%) of the HPV rearrangements and deletions disrupted the E1 and E2 genes, and EP tumors overexpressed the E6 and E7 viral oncogenes, a similar profile to tumors with HPV integration. Tumors with putative multimer HPV integrations display HPV multimers and concatemers of human and viral sequences. Our data uncovered a novel mechanism for HPV16 to cause cancer without integration through aberrant episomal replication, and forming rearranged, mutated, and multimer episomes.

Study phs002810

The Genomic Landscape of Interval Colorectal Cancers

Interval colorectal cancers (CRC), cancers diagnosed after a screening/surveillance exam in which no cancer is detected, and before the date of the next recommended exam, reflect an unprecedented challenge in CRC detection and prevention. To better understand this poorly characterized CRC variant, we examined the clinical and mutational characteristics of interval CRCs in comparison to screen-detected CRCs. We used data from the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer randomized controlled trial (RCT) of flexible sigmoidoscopy (FS) screening, which enrolled 154,900 men and women aged 55 to 74 years between 1993 and 2001. Whole Exome Sequencing (WES) was performed on 323 samples from 168 participants (data available through dbGaP). We found colorectal cancers diagnosed between screening exams (interval cancers) had significantly increased risk of death than screen detected cancers although no significant molecular differences were observed between screen-detected and interval CRC at the whole exome sequencing level.

Study phs003093

Integrative Somatic and Germline Computational Biology to Redefine Clinical Actionability in Solid Tumors

Neuroendocrine tumors (NETs) are rare cancers that arise in the gastrointestinal tract and pancreas. The fundamental mechanisms driving gastroenteropancreatic NETs (GEP-NETs) growth remain incompletely elucidated; however, the heterogeneous clinical behavior of GEP-NETs suggests that both cellular lineage dynamics and tumor microenvironment influence tumor pathophysiology. Here, we performed single-cell RNA-sequencing (scRNA-seq) of fresh resections of GEP-NETs, including four pancreatic NETs, three small intestinal NETs, and one perigastric NET. We used single-cell sequencing to investigate the tumor and immune cellular landscapes of GEP-NET patients. Malignant GEP-NET gene and regulon expression was compared with normal, gastrointestinal endocrine cell differentiation and fate determination stages. We further characterized immune-immune and immune-tumor interaction networks within GEP-NETs, identifying novel therapeutic opportunities in the myeloid compartment of the microenvironment. Our findings highlight the transcriptomic heterogeneity that distinguishes the cellular landscapes of GEP-NET anatomic subtypes and reveal potential avenues for future precision medicine therapeutics.

Study phs003141

Deterministic Evolution and Stringent Selection During Pre-Neoplasia

The earliest events during human tumor initiation are poorly characterized but may hold clues as to how to detect and prevent malignancy. Here we model this occult process by engineering TP53 deficiency in primary human gastric organoids and performing experimental evolution in multiple clonally derived cultures over two years, thereby defining causal relationships between this common initiating genetic lesion and resulting phenotypes. TP53 loss induced progressive aneuploidy, including copy number alterations and complex structural variants that are common in established gastric cancers, and which accrued along a defined temporal order. Longitudinal single cell sequencing of TP53 deficient gastric organoids similarly indicates progression towards malignant transcriptional programs. Moreover, lineage tracing with expressed cellular barcodes revealed highly reproducible dynamics whereby initially rare subclones with shared transcriptional programs repeatedly attain clonal dominance. This powerful platform for experimental evolution reveals stringent selection and convergence at the genotypic and phenotypic levels in pre-malignant epithelial organoids, illuminating evolutionary constraints and barriers to malignant transformation.

Study phs003249

Spatial Transcriptomics Reveals Discrete Tumor Microenvironments and Autocrine Loops Within Ovarian Cancer Subclones

Ovarian masses from patients with high grade serous ovarian carcinoma undergoing debulking surgery were subjected to spatial transcriptomics profiling using the 10x Genomics Visium (fresh frozen) platform. Copy number inference using inferCNV predicted the presence of subclones with mutually exclusive copy number alterations (CNAs) in 5 of the 8 patient samples studied. In one patient, 3 subclones were predicted. For this patient sample, a serial section of the same tumor was used to microdissect regions corresponding to each of these subclones, and a 'normal' region predicted to contain only fibroblasts and no tumor cells. These microdissected regions were processed for low pass whole genome sequencing (WGS) and CNAs recorded using ichorCNA. An oral biopsy lacking tumor cells from an unrelated donor was used as a negative control for CNA inference. The CNAs predicted by inferCNV for the three subclones were validated by the low pass WGS and no CNAs were observed in the normal region containing fibroblasts.

Study phs003561

Impact of Genetic Polymorphisms on Human Immune Cell Gene Expression

While many genetic variants have been associated with risk for human diseases, how these variants affect gene expression in various cell types remains largely unknown. To address this gap, the DICE [Database of Immune Cell Expression, Expression quantitative trait loci (eQTLs) and Epigenomics] project was established. Considering all human immune cell types and conditions studied, we identified cis-eQTLs for a total of 12,254 unique genes, which represent 61% of all protein-coding genes expressed in these cell types. Strikingly, a large fraction (41%) of these genes showed a strong cis-association with genotype only in a single cell type. We also found that biological sex is associated with major differences in immune cell gene expression in a highly cell-specific manner. These datasets will help reveal the effects of disease risk-associated genetic polymorphisms on specific immune cell types, providing mechanistic insights into how they might influence pathogenesis.

Study phs001703

Functional Genomic Landscape of Acute Myeloid Leukemia

The implementation of targeted therapies for acute myeloid leukemia has been challenged by complex mutational patterns within and across patients as well as a dearth of pharmacologic agents for most mutational events. The initial findings from the Beat AML program were from a cohort of 672 tumor specimens collected from 562 patients. Additional patients have been added in subsequent versions. We assessed these specimens using whole exome sequencing, RNA-sequencing, and ex vivo drug sensitivity analyses. Our data reveal novel mutational events not previously detected in AML. We show association of drug response with mutational status, including instances of drug sensitivity that are specific to combinatorial mutational events. Integration with RNA-sequencing also revealed gene expression signatures, which predict a role of specific gene networks in drug response. Collectively, this report offers a dataset, accessible by the Beat AML data viewer (www.vizome.org), that can be leveraged to address clinical, genomic, transcriptomic, and functional inquiries into the biology of AML.

Study phs001657

Integrative Analysis for Multi-Omics Data in Non-Small-Cell Lung Cancer

We conducted epigenetic and transcriptomic mapping of primary non-small cell lung tumors and non-neoplastic tissues. 20 non-neoplastic lung tissues and 18 non-small cell lung tumors were obtained from Biorepository and Tissue Technology Shared Resource at Moores Cancer Center, UC San Diego. All tumor samples were in pathological stages I and II. 8 pairs of samples were "matched", meaning that the tumor and normal tissues came from the same patient. Microfluidic oscillatory washing–based chromatin immunoprecipitation followed by sequencing (MOWChIP-seq) was used to profile the binding of H3K4me1, H3K4me3, H3K9me3, H3K27ac and H3K27me3. SmartSeq-2 was used to map mRNA expression. We identified a large number of differentially modified regions for both epigenetic and transcriptomic markers between tumors and normal tissues. Deep learning model showed extensive transcription factor network rewiring. Raw sequencing data of the ChIP-seq and RNA-seq libraries are available through this dbGaP submission.

Study phs003113

Structure of the Mucosal and Stool Microbiome in Lynch Syndrome

The gut microbiota has been associated with colorectal cancer (CRC), but causal alterations preceding CRC have not been elucidated. To prospectively assess microbiome changes prior to colorectal neoplasia, we investigated samples from 100 Lynch syndrome patients using 16S rRNA gene sequencing of colon biopsies, coupled with metagenomic and metatranscriptomic sequencing of feces. Colectomy and CRC history represented the largest effects on microbiome profiles. A subset of Clostridiaceae were depleted in stool corresponding with baseline adenomas, while Desulfovibrio was enriched in both stool and mucosal biopsies. A classifier leveraging stool metatranscriptomes resulted in modest power to predict interval development of preneoplastic colonic adenoma. Predictive transcripts corresponded with a shift in flagellin contributors and oxidative metabolic microenvironment, potentially factors in local CRC pathogenesis. This suggests that the effectiveness of prospective microbiome monitoring for adenomas may be limited but supports the potential causality of these consistent, early microbial changes in colonic neoplasia.

Study phs002343

ZNF703 is a common Luminal B breast cancer oncogene that differentially regulates luminal and basal progenitors in human mammary epithelium.

The telomeric amplicon at 8p12 is common in oestrogen receptor-positive (ER+) breast cancers. Array-CGH and expression analyses of 1172 primary breast tumours revealed that ZNF703 was the single gene within the minimal amplicon and was amplified predominantly in the Luminal B subtype. Amplification was shown to correlate with increased gene and protein expression and was associated with a distinct expression signature and poor clinical outcome. ZNF703 transformed NIH 3T3 fibroblasts, behaving as a classical oncogene, and regulated proliferation in human luminal breast cancer cell lines and immortalized human mammary epithelial cells. Manipulation of ZNF703 expression in the luminal MCF7 cell line modified the effects of TGFÎ² on proliferation. Overexpression of ZNF703 in normal human breast epithelial cells enhanced the frequency of in vitro colony-forming cells from luminal progenitors. Taken together, these data strongly point to ZNF703 as a novel oncogene in Luminal B breast cancer.

Study EGAS00000000082

Homopolymer switches mediate adaptive mutability in mismatch repair-deficient colorectal cancer

Mismatch repair (MMR) deficient cancer evolves through the continuous erosion of coding homopolymers in target genes. Curiously, the MMR genes MSH6 and MSH3 also contain coding homopolymers and these are frequent mutational targets in MMR-deficient cancers. The impact of incremental MMR mutations on MMR-deficient colorectal cancer evolution is unknown. We show that microsatellite instability modulates DNA repair by toggling hypermutable mononucleotide homopolymer runs in MSH6 and MSH3 through stochastic frameshift switching. Spontaneous mutation and reversion modulates subclonal mutation rate, mutation bias, and clonal HLA and neoantigen diversity. Patient-derived organoids corroborate these observations and show that in the absence of immune selection MMR homopolymer sequences drift back into reading frame, suggesting a fitness cost of elevated mutation rates. Combined experimental and simulation studies demonstrate that subclonal immune selection favours incremental MMR mutations. Overall, our data demonstrate that MMR-deficient colorectal cancers fuel intratumour heterogeneity by adapting subclonal mutation rate and diversity to immune selection.

Study EGAS50000000297

Single cell chromatin accessibility allows analysis of the transposable element landscape, revealing shared features of immune tissue-residency

Tissue adaptation is required for regulatory T (Treg) cells to function within organs. Whether this program shares similarities between different tissue-localized immune populations is poorly understood. Here, we addressed this by analyzing single-cell chromatin accessibility data, including the transposable element (TE) landscape, of CD45+ immune cells from different tissues. We identified features of organ-specific tissue adaptation across different immune cells. Focusing on tissue-Treg cells, we found that the Treg tissue adaptation program was conserved in other tissue-localized immune cells, such as amphiregulin-producing Th17 cells. Accessible TEs can act as regulatory elements but their contribution to tissue adaptation is unclear. TE landscape analysis revealed an enrichment of specific transcription factor binding motifs in TE regions within accessible chromatin peaks. TEs, specifically from the LTR family, were located in enhancer regions and associated with tissue adaptation. These findings broaden our understanding of immune tissue-residency, an important step towards organ-specific immune interventions.

Study EGAS50000000350

Ultra-sensitive ctDNA monitoring required for predicting response and resistance to immunotherapy in advanced melanoma

Circulating tumor DNA (ctDNA) monitoring in peripheral blood has shown promise for disease surveillance and prognostication of ICI response. Yet even in the metastatic context, ctDNA signals can be missed, suggesting the need for increased assay sensitivity. We used a tumor-informed ctDNA assay capable of detection down to 1 part-per-million (PPM) ctDNA to profile 188 plasma samples from 23 melanoma patients receiving ICI over several years. Residual disease was detected in ctDNA over a broad range, from 130,000 PPM down to 2.3 PPM, with approximately a quarter of detections below 50 PPM. Early on-treatment increases in ctDNA level, and both ctDNA-based molecular clearance (mCR) and molecular progression (mPD) were all prognostic of both OS and PFS. Additionally, mCR consistently preceded radiographic imaging. Our results show the importance and utility of an ultra-sensitive ctDNA assay in advanced melanoma treated by ICI with potential implications for other cancers.

Study EGAS50000000550

Genome sequencing identifies splice-disrupting variants in childhood heart disease

We used genome sequencing (GS) to identify cardiac specific splice disrupting variants that were subsequently validated in a subset of participants. In turn, we developed a heart-specific model for canonical and non-canonical splice variants, which was applied to patients with congenital heart disease (CHD). These included patients with two of the most common forms of cyanotic CHD i.e. tetralogy of Fallot (TOF) and dextro-transposition of the great arteries (TGA). In addition to identifying canonical splice-disrupting variants in known CHD-related genes in 1% cases, this approach identified putatively damaging non-canonical splice-disrupting variants in 11% of isolated CHD, with deeply intronic variants representing 53% of non-canonical splice-disrupting variants in CHD genes. GS was critical for the identification of variants that would not be captured by routine clinical genetic tests including exome sequencing, while cardiac RNA-Seq allowed for high specificity in the interpretation of splice-disrupting effects in the heart.

Study EGAS50000000586

KDM6A Loss Triggers an Epigenetic Switch that Disrupts Urothelial Identity and Drives Cell Proliferation in Bladder Cancer

Disruption of KDM6A, a histone lysine demethylase, is one of the most common somatic alternations in bladder cancer. How mutations of this chromatin modifier impact the epigenetic landscape to promote carcinogenesis is poorly understood. Here, we demonstrate that KDM6A loss triggers an epigenomic switch that disrupts urothelial identity and induces a neoplastic state characterized by increased cell proliferation. In bladder cancer cells with intact KDM6A, FOXA1 binds KDM6A at enhancers to activate genes instructing urothelial differentiation. In KDM6A-deficient cells, we observed simultaneous loss of FOXA1 target binding and genome-wide redistribution of the bZIP transcription factor ATF3, which in turn represses FOXA1 target genes and activates cell-cycle progression genes. Importantly, ATF3 depletion reverses the cell proliferation phenotype. These data establish that KDM6A loss creates an epigenetic state that drives tumor growth in an ATF3-dependent manner, forging a molecular vulnerability that can be targeted by novel therapeutic strategies.

Study phs002801

MutWP6__CRUK_Grand_Challenge_Mutographs_of_Cancer__alkylating_agents

The Mutographs project aims to advance our understanding of the causes of cancer through studies of mutational signatures. Led by Mike Stratton, together with Paul Brennan, Ludmil Alexandrov, Allan Balmain, David Phillips and Peter Campbell, this large-scale international research endeavour was awarded a Cancer Research UK Grand Challenge. Within Mutographs, work lead by the Sanger Institute will investigate whether detection of somatic mutations and mutational signatures in circulating white blood cells can be developed into a practical, generic system for surveying and monitoring multiple different endogenous and exogenous exposures, providing an ‘observatory’ on somatic mutational processes in humans. Whole genome sequences are generated at the Wellcome Sanger Institute (Illumina HiSeqX). Somatic mutational signatures are subsequently extracted by non-negative matrix factorisation methods. Through an enhanced understanding of cancer aetiology, Mutographs unprecedented effort is anticipated to outline modifiable risk factors, lead to new approaches to prevent cancer, and provide opportunities to empower early detection, refine high-risk groups and contribute to further therapeutic development.

Study EGAS00001003637

MutWP6__CRUK_Grand_Challenge_Mutographs_of_Cancer__oncology_agents

he Mutographs project aims to advance our understanding of the causes of cancer through studies of mutational signatures. Led by Mike Stratton, together with Paul Brennan, Ludmil Alexandrov, Allan Balmain, David Phillips and Peter Campbell, this large-scale international research endeavour was awarded a Cancer Research UK Grand Challenge. Within Mutographs, work lead by the Sanger Institute will investigate whether detection of somatic mutations and mutational signatures in circulating white blood cells can be developed into a practical, generic system for surveying and monitoring multiple different endogenous and exogenous exposures, providing an ‘observatory’ on somatic mutational processes in humans. Whole genome sequences are generated at the Wellcome Sanger Institute (Illumina HiSeqX). Somatic mutational signatures are subsequently extracted by non-negative matrix factorisation methods. Through an enhanced understanding of cancer aetiology, Mutographs unprecedented effort is anticipated to outline modifiable risk factors, lead to new approaches to prevent cancer, and provide opportunities to empower early detection, refine high-risk groups and contribute to further therapeutic development.

Study EGAS00001004125

Spatial atlas of human atherosclerosis highlights role of the microvasculature in disease

Atherosclerosis is a pervasive contributor to ischemic heart disease and stroke. Despite the advance of lipid lowering-therapies and antihypertensive agents, the residual risk of an atherosclerotic event remains high and developing therapeutic strategies has proven challenging. This is due to the complexity of atherosclerosis with a spatial interplay of multiple cell types within the vascular wall. Here we generate an integrative high-resolution map of human atherosclerotic plaques combining single-cell RNA-seq from multiple studies and spatial transcriptomics data from 12 human specimens, with different stages of atherosclerosis. We show cell-type and atherosclerosis-specific expression changes and spatially constrained alterations in cell-cell communication. We highlight the possible recruitment of lymphocytes via ACKR1 endothelial cells of the vasa vasorum, the migration of vascular smooth muscle cells towards the lumen by transforming into fibromyocytes, and cell-cell communication in the plaque region, indicating an intricate cellular interplay within the adventitia and the subendothelial space in human atherosclerosis.

Study EGAS50000000660

Gabriella Miller Kids First Pediatric Research Program in Enchondromatoses and Related Malignant Tumors

Chondrosarcoma is a malignant tumor that originates from cartilaginous cells. It is the third most common primary malignancy of bone after myeloma and osteosarcoma. It accounts for about 20% of bone tumors and is diagnosed in approximately 600 patients each year in the United States. Up to 40% of the chondrosarcomas arise from an enchondroma. Enchondromas are benign, intramedullary cartilaginous tumors of bone. They can be solitary or multiple and are present in >3% of the population. Enchondromatosis refers to a group of diseases characterized by multiple enchondromas including metachondromatosis (MC), Ollier disease (OD), and Maffucci syndrome (MS) among others. All have skeletal abnormalities with or without associated vascular anomalies that can cause severe limb deformities during early childhood. The risk for chondrosarcoma is up to 30% in OD and MS. Currently, the only treatment for patients with these disorders is surgical; there is no effective pharmacologic therapy. The molecular bases of these two conditions is not well understood.

Study phs001987

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