Project description:In principle, whole-genome sequencing (WGS) of the human genome even at low coverage offers higher resolution for genomic copy number variation (CNV) detection compared to array-based technologies, which is currently the first-tier approach in clinical cytogenetics. There are, however, obstacles in replacing array-based CNV detection with that of low-coverage WGS such as cost, turnaround time, and lack of systematic performance comparisons. With technological advances in WGS in terms of library preparation, instrument platforms, and data analysis algorithms, obstacles imposed by cost and turnaround time are fading. However, a systematic performance comparison between array and low-coverage WGS-based CNV detection has yet to be performed. Here, we compared the CNV detection capabilities between WGS (short-insert, 3kb-, and 5kb-mate-pair libraries) at 1X, 3X, and 5X coverages and standardly used high-resolution arrays in the genome of 1000-Genomes-Project CEU genome NA12878. CNV detection was performed using standard analysis methods, and the results were then compared to a list of Gold Standard NA12878 CNVs distilled from the 1000-Genomes Project. Overall, low-coverage WGS is able to detect drastically more (approximately 5 fold more on average) Gold Standard CNVs compared to arrays and is accompanied with fewer CNV calls without secondary validation. Furthermore, we also show that WGS (at ≥1X coverage) is able to detect all seven validated deletions larger than 100 kb in the NA12878 genome whereas only one of such deletions is detected in most arrays. Finally, we show that the much larger 15 Mbp Cri-du-chat deletion can be clearly seen at even 1X coverage from short-insert WGS.
Project description:Low coverage whole genome sequencing (lc-WGS) from inducible Tet TKO (Tet iTKO) and control (Ctrl) mouse ESCs (mESC), as well as for germline Dnmt TKO mESCs. mESCs were sorted to isolate the Live/Dead dye and Thy1.2 negative CD326+GFP+ population representing the mESCs populations responsive to the tamoxifen treatment. The cells were resuspended in FACS buffer and filtered with a 70 µM filter before sorting. These bulk-population samples were analyzed by using low coverage Whole Genome Sequencing (lc-WGS).
Project description:Chromosomal copy number variations (CNV) have been associated with various neurological and developmental disorders and chromosomal microarray (CMA) is a method of choice to diagnose Copy Number Gain/Loss syndromes. Recently, next-generation sequencing (NGS)-based low-coverage whole genome sequencing (LC-WGS) has been applied to detect Copy Number Gain/Loss syndromes. This dataset is intended to be used as a “Golden standard data set” for development of LC-WGS analysis method. It consists of patients (n=63) who have a mental delay and/or physical disability phenotype and normal (n=20) phenotype.
Project description:We performed shallow whole genome sequencing (WGS) on circulating free (cf)DNA extracted from plasma or cerebrospinal fluid (CSF), and shallow WGS on the tissue DNA extracted from the biopsy in order to evaluate the correlation between the two biomaterials. After library construction and sequencing (Hiseq3000 or Ion Proton), copy number variations were called with WisecondorX.
Project description:Aneuploidy is prevalent in cancer, conferring fitness advantage, multidrug resistance, and poor prognosis. In contrast, experimentally induced aneuploidy often results in adverse effects and impaired proliferation. This paradox underscores the necessity of cancer cells to adapt to abnormal chromosome numbers. To identify molecular mechanisms of adaptation to aneuploidy, we initiated in vitro evolution of cells with extra chromosomes added via microcell-mediated chromosome transfer. To this end, we cultured cells in a nutrient-rich medium for 50 passages or plated the cells at a low density and selectively collected the largest colonies originating from a single cell (colony selection). The anaylsis of somatic copy number variations in the evolved cell lines was then carried out based on low-coverage whole genome sequencing (WGS) and array-based comparative genomic hybridization (aCGH).
Project description:Diagnosis of glioma into the hierarchy of human brain development would greatly facilitate mechanistic studies and clinical services in combating glioma. By analysing the multi-dimension big data of glioma genome and clinical manifestations, we have recently developed an EM/PM classification scheme anchored in the brain development and glioma pathogenesis (Sun et al., PNAS 111:3538-3543, 2014). To translate the EM/PM classification into a clinical diagnostic tool, we here designed and validated a TaqMan low-density RT-PCR array (TLDA) and a support vector machine (SVM) based prediction model that enables individual diagnosis of gliomas into the EM/PM subtype with high accuracy and precision. Results of 153 individually diagnosed adult diffuse gliomas of WHO grades II-IV derived from Chinese or Swedish patients confirmed our previous data base investigations: EM and PM gliomas show distinct prognosis, occur at different ages, and harbor mutually exclusive patterns of genomic alterations detected by Sanger sequencing and shallow-coverage whole genome sequencing (WGS). Further, we show that shallow-coverage WGS enabled a systematic identification of clonal and subclonal copy number variations (CNV) in glioma genomes, and the extent and the pattern of CNV can serve as an objective marker of tumor progression in the PM gliomas harboring IDH mutations.
Project description:Diagnosis of glioma into the hierarchy of human brain development would greatly facilitate mechanistic studies and clinical services in combating glioma. By analysing the multi-dimension big data of glioma genome and clinical manifestations, we have recently developed an EM/PM classification scheme anchored in the brain development and glioma pathogenesis (Sun et al., PNAS 111:3538-3543, 2014). To translate the EM/PM classification into a clinical diagnostic tool, we here designed and validated a TaqMan low-density RT-PCR array (TLDA) and a support vector machine (SVM) based prediction model that enables individual diagnosis of gliomas into the EM/PM subtype with high accuracy and precision. Results of 153 individually diagnosed adult diffuse gliomas of WHO grades II-IV derived from Chinese or Swedish patients confirmed our previous data base investigations: EM and PM gliomas show distinct prognosis, occur at different ages, and harbor mutually exclusive patterns of genomic alterations detected by Sanger sequencing and shallow-coverage whole genome sequencing (WGS). Further, we show that shallow-coverage WGS enabled a systematic identification of clonal and subclonal copy number variations (CNV) in glioma genomes, and the extent and the pattern of CNV can serve as an objective marker of tumor progression in the PM gliomas harboring IDH mutations.