Project description:Thomas Hunt Morgan and colleagues identified variation in gene copy number in Drosophila in the 1920s and 1930s and linked such variation to phenotypic differences [Bridges, C. B. (1936) Science 83, 210]. Yet the extent of variation in the number of chromosomes, chromosomal regions, or gene copies, and the importance of this variation within species, remain poorly understood. Here, we focus on copy-number variation in Drosophila melanogaster. We characterize copy-number polymorphism (CNP) across genomic regions, and we contrast patterns to infer the evolutionary processes acting on this variation. Copy-number variation in D. melanogaster is non-randomly distributed, presumably due to a mutational bias produced by tandem repeats or other mechanisms. Comparisons of coding and noncoding CNPs, however, reveal a strong effect of purifying selection in the removal of structural variation from functionally constrained regions. Most patterns of CNP in D. melanogaster suggest that negative selection and mutational biases are the primary agents responsible for shaping structural variation. Keywords: comparative genomic hybridization
Project description:CGH was used to compare structural variation among four soybean cultivars (Archer, Minsoy, Noir1 and Williams 82). Four additional hybridizations were performed with these and other accessions (Kingwa, Williams, M92-220, Richland and Essex) to confirm the patterns observed.
Project description:Pancreatic cancer remains one of the most lethal of malignancies and a major health burden. We performed whole genome sequencing and CNV analysis of 100 pancreatic ductal adenocarcinomas. Chromosomal rearrangements leading to gene disruption were frequent, affecting genes known to be important in pancreatic cancer (TP53, SMAD4, CDKN2A, ARID1A, ROBO2) and novel candidate drivers of pancreatic carcinogenesis (KDM6A and PREX2). Patterns of structural variation classified PDAC into 4 subtypes with potential clinical utility: stable, locally rearranged, scattered and unstable. A significant proportion harboured focal amplifications, many of which contained druggable oncogenes (ERBB2, MET, FGFR1, CDK6, PIK3R3, and PIK3CA), but at low individual frequency. Genomic instability co-segregated with inactivation of DNA maintenance genes (BRCA1, BRCA2, PALB2 or RPA1), and a mutational signature of DNA damage repair deficiency. This subgroup was associated with response to platinum-based therapy and defines candidate biomarkers of therapeutic responsiveness.
Project description:Structural variation has played an important role in the evolutionary restructuring of human and great ape genomes. We generated approximately 10-fold genomic sequence coverage from a western lowland gorilla and integrated these data into a physical and cytogenetic framework to develop a comprehensive view of structural variation. We discovered and validated over 7,665 structural changes within the gorilla lineage including sequence resolution of inversions, deletions, duplications and retrotranspositions. A comparison with human and other ape genomes shows that the gorilla genome has been subjected to the highest rate of segmental duplication. We show that both the gorilla and chimpanzee genomes have experienced independent yet parallel patterns of structural mutation that have not occurred in humans, including the formation of subtelomeric heterochromatic caps, the hyperexpansion of segmental duplications and bursts of retroviral integrations. Our analysis suggests that the chimpanzee and gorilla genomes are structurally more derived than either orangutan or human.
Project description:We have used massively parallel paired end sequencing strategies to reconstruct the genomic landscape of 24 breast cancer genomes, through the identification and characterization of 2166 somatically acquired genomic rearrangements. These studies have revealed considerable complexity in the patterns of structural variation, identified novel fusion genes and unveiled new insights into the complex structure of amplicons.
Project description:Rhabdomyosarcoma (RMS) is a pediatric soft tissue cancer with no precision therapy available for affected patients. We hypothesized that with a general paucity of known mutations in RMS, chromatin structural driving mechanisms are essential for tumor proliferation. Thus, we carried out high-depth in situ Hi-C in representative cell lines and patient-derived xenografts to understand chromatin architecture in each major RMS subtype. We report a comprehensive 3D chromatin structural analysis and characterization of fusion-positive (FP-RMS) and fusion-negative rhabdomyosarcoma (FN-RMS). We have generated spike-in in situ Hi-C chromatin interaction maps for the commonest FP-RMS and FN-RMS cell lines, and compared our data with patient derived xenograft (PDX) models. In our studies we uncover common and distinct structural elements in large Mb-scale chromatin compartments, tumor-essential genes within variable topologically associating domains, and unique patterns of structural variation. This study enables a comprehensive resource for contextualizing gene regulation events in RMS, and high-depth chromatin interactivity maps for identification of functionally critical chromatin domains in this tumor.