scholarly journals Reducing False Positives in CRISPR/Cas9 Screens from Copy Number Variations

2018 ◽  
Author(s):  
Alexander Wu ◽  
Tengfei Xiao ◽  
Teng Fei ◽  
X. Shirley Liu ◽  
Wei Li
Keyword(s):  
Copy Number ◽  
Sliding Window ◽  
Copy Number Variations ◽  
False Positives ◽  
Screening Experiments ◽  
Copy Numbers ◽  
Cas9 Nuclease ◽  
Wide Range ◽  
Window Approach ◽  
Genomic Regions

AbstractCRISPR/Cas9 knockout screens have been widely used to interrogate gene functions across a wide range of cell systems. However, the screening outcome is biased in amplified genomic regions, due to the ability of the Cas9 nuclease to induce multiple double-stranded breaks and strong DNA damage responses at these regions. We developed algorithms to correct biases associated with copy number variations (CNV), even when the CNV profiles are unknown. We demonstrated that our methods effectively reduced false positives in amplified regions while preserving signals of true positives. In addition, we developed a sliding window approach to estimate regions of high copy numbers for cases in which CNV information is not available. These copy number estimations can subsequently be used to effectively correct CNV-related biases in CRISPR screening experiments. Our approach is integrated into the existing MAGeCK/MAGeCK-VISPR analysis pipelines and provides a convenient framework to improve the precision of CRISPR screening results.

Somatic Mosaicism in Bulls Estimated from Genome-Wide CNV Array and TSPY Gene Copy Numbers

2016 ◽  
Vol 149 (3) ◽  
pp. 176-181 ◽  
Author(s):  
Olutobi A. Oluwole ◽  
Tamas Revay ◽  
Kiana Mahboubi ◽  
Laura A. Favetta ◽  
W. Allan King
Keyword(s):  
Copy Number ◽  
De Novo ◽  
Somatic Mosaicism ◽  
Copy Number Variations ◽  
Tissue Type ◽  
Gene Copy ◽  
Copy Numbers ◽  
Genome Wide ◽  
Wide Range ◽  
Tspy Gene

Somatic mosaicism has become a focus in human research due to the implications of individual genetic variability in disease. Here, we assessed somatic copy number variations (CNVs) in Holstein bulls in 2 respects. We estimated genome-wide CNVs and assayed CNVs of the TSPY gene, the most variable bovine gene from the Y chromosome. Somatic tissues (blood, lung, heart, muscle, testis, and brain) of 4 bulls were arrayed on the Illumina Bovine SNP50k chip and qPCR tested for TSPY copy numbers. Our results showed extensive copy number divergence in tissues within the same animal as well as significant copy number alterations of TSPY. We detected a mean of 31 CNVs per animal among which 14 were of germline origin, as they were constantly present in all investigated tissues of the animal, while 18 were specific to 1 tissue. Thus, 57% of the total number of detected CNVs was the result of de novo somatic events. Further, TSPY copy number was found to vary significantly among tissues as well as among the same tissue type from different animals in a wide range from 7 to 224% of the calibrator. Our study shows significant autosomal and Y-chromosomal de novo somatic CNV in bulls.

scholarly journals Dynamics in Copy Numbers of Five Plasmids of a DairyLactococcus lactisStrain under Dairy-Related Conditions Including Near-Zero Growth Rates

2018 ◽  
Vol 84 (11) ◽  
Author(s):  
Oscar van Mastrigt ◽  
Marcel M. A. N. Lommers ◽  
Yorick C. de Vries ◽  
Tjakko Abee ◽  
Eddy J. Smid
Keyword(s):  
Nutrient Limitation ◽  
Lactococcus Lactis ◽  
Growth Rates ◽  
Copy Number ◽  
Plasmid Copy ◽  
Content Type ◽  
Copy Numbers ◽  
Wide Range ◽  
Zero Growth ◽  
The Impact

ABSTRACTLactic acid bacteria can carry multiple plasmids affecting their performance in dairy fermentations. The expression of plasmid-borne genes and the activity of the corresponding proteins are severely affected by changes in the numbers of plasmid copies. We studied the impact of growth rate on the dynamics of plasmid copy numbers at high growth rates in chemostat cultures and down to near-zero growth rates in retentostat cultures. Five plasmids of the dairy strainLactococcus lactisFM03-V1 were selected, and these varied in size (3 to 39 kb), in replication mechanism (theta or rolling circle), and in putative (dairy-associated) functions. The copy numbers ranged from 1.5 to 40.5, and the copy number of theta-type replicating plasmids was negatively correlated to the plasmid size. Despite the extremely wide range of growth rates (0.0003 h−1to 0.6 h−1), the copy numbers of the five plasmids were stable and only slightly increased at near-zero growth rates, showing that the plasmid replication rate was strictly controlled. One low-copy-number plasmid, carrying a large exopolysaccharide gene cluster, was segregationally unstable during retentostat cultivations, reflected in a complete loss of the plasmid in one of the retentostat cultures. The copy number of the five plasmids was also hardly affected by varying the pH value, nutrient limitation, or the presence of citrate (maximum 2.2-fold), signifying the stability in copy number of the plasmids.IMPORTANCELactococcus lactisis extensively used in starter cultures for dairy fermentations. Important traits for the growth and survival ofL. lactisin dairy fermentations are encoded by genes located on plasmids, such as genes involved in lactose and citrate metabolism, protein degradation, oligopeptide uptake, and bacteriophage resistance. Because the number of plasmid copies could affect the expression of plasmid-borne genes, it is important to know the factors that influence the plasmid copy numbers. We monitored the plasmid copy numbers ofL. lactisat near-zero growth rates, characteristic for cheese ripening. Moreover, we analyzed the effects of pH, nutrient limitation, and the presence of citrate. This showed that the plasmid copy numbers were stable, giving insight into plasmid copy number dynamics in dairy fermentations.

scholarly journals Rapid and reliable detection of α-globin copy number variations by quantitative real-time PCR

2014 ◽  
Vol 14 (1) ◽  
Author(s):  
Runa M Grimholt ◽  
Petter Urdal ◽  
Olav Klingenberg ◽  
Armin P Piehler
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Copy Number ◽  
Globin Gene ◽  
Copy Number Variations ◽  
Globin Genes ◽  
Quantitative Real Time Pcr ◽  
Human Genetic Disease ◽  
Large Deletions ◽  
Wide Range

Abstract Background Alpha-thalassemia is the most common human genetic disease worldwide. Copy number variations in the form of deletions of α-globin genes lead to α-thalassemia while duplications of α-globin genes can cause a severe phenotype in β-thalassemia carriers due to accentuation of globin chain imbalance. It is important to have simple and reliable methods to identify unknown or rare deletions and duplications in cases in which thalassemia is suspected but cannot be confirmed by multiplex gap-PCR. Here we describe a copy number variation assay to detect deletions and duplications in the α-globin gene cluster (HBA-CNV). Results Quantitative real-time PCR was performed using four TaqMan® assays which specifically amplify target sequences representing both the α-globin genes, the –α3.7 deletion and the HS-40 region. The copy number for each target was determined by the 2-ΔΔCq method. To validate our method, we compared the HBA-CNV method with traditional gap-PCR in 108 samples from patients referred to our laboratory for hemoglobinopathy evaluation. To determine the robustness of the four assays, we analyzed samples with and without deletions diluted to obtain different DNA concentrations. The HBA-CNV method identified the correct copy numbers in all 108 samples. All four assays showed the correct copy number within a wide range of DNA concentrations (3.2-100 ng/μL), showing that it is a robust and reliable method. By using the method in routine diagnostics of hemoglobinopathies we have also identified several deletions and duplications that are not detected with conventional gap-PCR. Conclusions HBA-CNV is able to detect all known large deletions and duplications affecting the α-globin genes, providing a flexible and simple workflow with rapid and reliable results.

scholarly journals Eight Y chromosome genes show copy number variations in horses

2018 ◽  
Vol 61 (3) ◽  
pp. 263-270
Author(s):  
Haoyuan Han ◽  
Xin Zhang ◽  
Xiaocheng Zhao ◽  
Xiaoting Xia ◽  
Chuzhao Lei ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Copy Number ◽  
Distribution Patterns ◽  
Single Copy ◽  
Copy Number Variations ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Specific Transcript ◽  
Copy Numbers ◽  
The Impact

Abstract. Copy number variations (CNVs), which represent a significant source of genetic diversity on the Y chromosome in mammals, have been shown to be associated with the development of many complex phenotypes, such as reproduction and male fertility. The occurrence of CNVs has been confirmed on the Y chromosome in horses. However, the copy numbers (CNs) of Equus caballus Y chromosome (ECAY) genes are largely unknown. To demonstrate the copy number variations of Y chromosome genes in horses, the quantitative real-time polymerase chain reaction (qPCR) method was applied to measure the CNVs of the eukaryotic translation initiation factor 1A Y (EIF1AY), equine testis-specific transcript on Y 1 (ETSTY1), equine testis-specific transcript on Y 4 (ETSTY4), equine testis-specific transcript on Y 5 (ETSTY5), equine transcript Y4 (ETY4), ubiquitin activating enzyme Y (UBE1Y), sex determining region Y (SRY), and inverted repeat 2 Y (YIR2) across 14 Chinese domestic horse breeds in this study. Our results revealed that these eight genes were multi-copy; furthermore, some of the well acknowledged single-copy genes such as SRY and EIF1AY were found to be multi-copy in this research. The median copy numbers (MCNs) varied among different breeds for the same gene. The CNVs of Y chromosome genes showed different distribution patterns among Chinese horse breeds, indicating the impact of natural selection on copy numbers. Our results will provide fundamental information for future functional studies.

scholarly journals Copy Number Variations of CEP63, FOSL2 and PAQR6 Serve as Novel Signatures for the Prognosis of Bladder Cancer

2021 ◽  
Vol 11 ◽  
Author(s):  
Zhao Cai ◽  
Huang Chen ◽  
Jingqiao Bai ◽  
Yang Zheng ◽  
Jianhui Ma ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
Prognostic Factors ◽  
High Risk ◽  
Copy Number ◽  
Copy Number Variations ◽  
Invasive Bladder Cancer ◽  
Gene Copy ◽  
Muscle Invasive Bladder Cancer ◽  
Copy Numbers ◽  
Muscle Invasive

BackgroundFinding effective prognostic signatures is of great urgency due to the high risk of recurrence and progression of bladder cancer (BC). Although a lot of genetic alterations are involved in the carcinogenesis, none of them were referred in the current risk group stratifications. In this study, we aimed to find significant copy number variations (CNVs) to predict prognosis for BC patients.MethodsCNVs with high aberration frequencies in BC were explored by array-based comparative genomic hybridization in 65 tumor samples. Candidates were validated in independent groups of BC tumor samples (n=219) and urine samples (n=123). 3D digital PCR was applied for detecting accurate gene copy numbers in BC urine. In order to explore the prognostic value of candidate CNVs, all enrolled patients were followed up for the disease-free survival (DFS). Cox proportional hazards regression analysis was performed to find the independent prognostic factors for DFS.ResultsCNVs of CEP63, FOSL2 and PAQR6 with high aberration frequencies (67.7%, 56.9% and 60.0%, respectively) were found in BC tumors. Copy numbers of CEP63, FOSL2 and PAQR6 were gained in 219 tumor samples. CNVs of CEP63 and FOSL2 were correlated with advanced tumor stage and high grade. Retrospective analysis (median follow-up time: 69 months) revealed that CNVs of CEP63 and FOSL2 were independent prognostic factors for DFS of non-muscle-invasive bladder cancer (NMIBC) patients, while CNVs of FOSL2 and PAQR6 were independent prognostic factors for DFS of muscle-invasive bladder cancer (MIBC) patients. Models for predicting DFS were constructed based on CNVs of three genes. Patients with high prognostic indexes tended to have poor DFS. Prognostic index can also help to identify those with worse outcomes among high risk NMIBC patients. Copy number gains of CEP63 and FOSL2 in urine were found to be significantly correlated with poor DFS of NMIBC patients.ConclusionsCNVs of CEP63, FOSL2 and PAQR6 were capable of predicting DFS and may serve as promising signatures for prognosis of BC.

scholarly journals The ELIXIR Human Copy Number Variations Community: building bioinformatics infrastructure for research

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 1229
Author(s):  
David Salgado ◽  
Irina M. Armean ◽  
Michael Baudis ◽  
Sergi Beltran ◽  
Salvador Capella-Gutierrez ◽  
...  
Keyword(s):  
Copy Number ◽  
High Throughput Sequencing ◽  
Population Genomics ◽  
Genetic Diseases ◽  
White Paper ◽  
Copy Number Variations ◽  
Direct Result ◽  
Sequencing Technologies ◽  
Wide Range ◽  
Definition Of

Copy number variations (CNVs) are major causative contributors both in the genesis of genetic diseases and human neoplasias. While “High-Throughput” sequencing technologies are increasingly becoming the primary choice for genomic screening analysis, their ability to efficiently detect CNVs is still heterogeneous and remains to be developed. The aim of this white paper is to provide a guiding framework for the future contributions of ELIXIR’s recently established human CNV Community, with implications beyond human disease diagnostics and population genomics. This white paper is the direct result of a strategy meeting that took place in September 2018 in Hinxton (UK) and involved representatives of 11 ELIXIR Nodes. The meeting led to the definition of priority objectives and tasks, to address a wide range of CNV-related challenges ranging from detection and interpretation to sharing and training. Here, we provide suggestions on how to align these tasks within the ELIXIR Platforms strategy, and on how to frame the activities of this new ELIXIR Community in the international context.

scholarly journals Copy number variations in candidate genomic regions confirm genetic heterogeneity and parental bias in Hirschsprung disease

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Francesca Lantieri ◽  
Stefania Gimelli ◽  
Chiara Viaggi ◽  
Elissavet Stathaki ◽  
Michela Malacarne ◽  
...  
Keyword(s):  
Nervous System ◽  
Enteric Nervous System ◽  
Genetic Heterogeneity ◽  
Copy Number ◽  
System Development ◽  
Hirschsprung Disease ◽  
Copy Number Variations ◽  
Nervous System Development ◽  
Comparative Genomic ◽  
Genomic Regions

Abstract Background Hirschsprung Disease (HSCR) is a congenital defect of the intestinal innervations characterized by complex inheritance. Many susceptibility genes including RET, the major HSCR gene, and several linked regions and associated loci have been shown to contribute to disease pathogenesis. Nonetheless, a proportion of patients still remains unexplained. Copy Number Variations (CNVs) have already been involved in HSCR, and for this reason we performed Comparative Genomic Hybridization (CGH), using a custom array with high density probes. Results A total of 20 HSCR candidate regions/genes was tested in 55 sporadic patients and four patients with already known chromosomal aberrations. Among 83 calls, 12 variants were experimentally validated, three of which involving the HSCR crucial genes SEMA3A/3D, NRG1, and PHOX2B. Conversely RET involvement in HSCR does not seem to rely on the presence of CNVs while, interestingly, several gains and losses did co-occur with another RET defect, thus confirming that more than one predisposing event is necessary for HSCR to develop. New loci were also shown to be involved, such as ALDH1A2, already found to play a major role in the enteric nervous system. Finally, all the inherited CNVs were of maternal origin. Conclusions Our results confirm a wide genetic heterogeneity in HSCR occurrence and support a role of candidate genes in expression regulation and cell signaling, thus contributing to depict further the molecular complexity of the genomic regions involved in the Enteric Nervous System development. The observed maternal transmission bias for HSCR associated CNVs supports the hypothesis that in females these variants might be more tolerated, requiring additional alterations to develop HSCR disease.

Association analysis of SSTR2 copy number variation with cattle stature and its expression analysis in Chinese beef cattle

2019 ◽  
Vol 157 (04) ◽  
pp. 365-374 ◽  
Author(s):  
J. Cheng ◽  
R. Jiang ◽  
X. K. Cao ◽  
M. Liu ◽  
Y. Z. Huang ◽  
...  
Keyword(s):  
Association Analysis ◽  
Copy Number ◽  
Growth Traits ◽  
Somatostatin Receptor ◽  
Mrna Level ◽  
Copy Number Variations ◽  
Economic Traits ◽  
Marbling Score ◽  
Wide Range ◽  
Number Variation

AbstractCopy number variations (CNVs), as an important source of genetic variation, can affect a wide range of phenotypes by diverse mechanisms. The somatostatin receptor 2 (SSTR2) gene plays important roles in cell proliferation and apoptosis. Recently, this gene was mapped to a CNV region, which encompasses quantitative trait loci of cattle economic traits including body weight, marbling score, etc. Therefore, SSTR2 CNV may exhibit phenotypic effects on cattle growth traits. In the current study, distribution of SSTR2 gene CNVs was investigated in six Chinese cattle breeds (XN, QC, NY, JA, LX and PN), and the results showed higher CNV polymorphisms in XN, QC and NY cattle. Next, association analysis between growth traits and SSTR2 CNV was performed for XN, QC and NY cattle. In NY, individuals with fewer copies showed better performance than those with more copies. Further, the effects of SSTR2 CNV on the SSTR2 mRNA level were also investigated, but revealed no significant correlation in either muscle or adipose tissue of adult NY cattle. The results suggested the potential for use of SSTR2 CNV as a marker for the molecular breeding of NY cattle.

scholarly journals Genome-wide copy number variations in a large cohort of bantu African children

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Feyza Yilmaz ◽  
Megan Null ◽  
David Astling ◽  
Hung-Chun Yu ◽  
Joanne Cole ◽  
...  
Keyword(s):  
Copy Number ◽  
Developmental Disorders ◽  
African Ancestry ◽  
22Q11.2 Deletion Syndrome ◽  
Copy Number Variations ◽  
Genomic Variation ◽  
Deletion Syndrome ◽  
Genome Wide ◽  
A Genome ◽  
Genomic Regions

Abstract Background Copy number variations (CNVs) account for a substantial proportion of inter-individual genomic variation. However, a majority of genomic variation studies have focused on single-nucleotide variations (SNVs), with limited genome-wide analysis of CNVs in large cohorts, especially in populations that are under-represented in genetic studies including people of African descent. Methods We carried out a genome-wide copy number analysis in > 3400 healthy Bantu Africans from Tanzania. Signal intensity data from high density (> 2.5 million probes) genotyping arrays were used for CNV calling with three algorithms including PennCNV, DNAcopy and VanillaICE. Stringent quality metrics and filtering criteria were applied to obtain high confidence CNVs. Results We identified over 400,000 CNVs larger than 1 kilobase (kb), for an average of 120 CNVs (SE = 2.57) per individual. We detected 866 large CNVs (≥ 300 kb), some of which overlapped genomic regions previously associated with multiple congenital anomaly syndromes, including Prader-Willi/Angelman syndrome (Type1) and 22q11.2 deletion syndrome. Furthermore, several of the common CNVs seen in our cohort (≥ 5%) overlap genes previously associated with developmental disorders. Conclusions These findings may help refine the phenotypic outcomes and penetrance of variations affecting genes and genomic regions previously implicated in diseases. Our study provides one of the largest datasets of CNVs from individuals of African ancestry, enabling improved clinical evaluation and disease association of CNVs observed in research and clinical studies in African populations.

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