Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
ALL Metrics
-
Views
-
Downloads
Get PDF
Get XML
Cite
Export
Track
Software Tool Article

AGA: Interactive pipeline for reproducible genomics analyses

[version 1; peer review: 2 approved]
PUBLISHED 28 Jan 2015
Author details Author details
OPEN PEER REVIEW
REVIEWER STATUS

This article is included in the RPackage gateway.

This article is included in the Bioinformatics gateway.

Abstract

Automated Genomics Analysis (AGA) is an interactive program to analyze high-throughput genomic data sets on a variety of platforms. An easy to use, point and click, guided pipeline is implemented to combine, define, and compare datasets, and customize their outputs. In contrast to other automated programs, AGA enables flexible selection of sample groups for comparison from complex sample annotations. Batch correction techniques are also included to further enable the combination of datasets from diverse studies in this comparison. AGA also allows users to save plots, tables and data, and log files containing key portions of the R script run for reproducible analyses. The link between the interface and R supports collaborative research, enabling advanced R users to extend preliminary analyses generated from bioinformatics novices.

Keywords

automated, genomic, analysis, datasets, DNA, methylation, expression, arrays

Introduction

While high dimensional genetic data have increased in availability at reduced cost, robust analyses remain labor intensive and costly. Numerous automated software pipelines have been developed in an effort to increase the rate and decrease the costs at which analyses can be completed, including SVAw10, Partek3, InSilicoDB17, and cBioPortal4. Automated Genomics Analysis (AGA) provides a more dynamic experience, allowing the user to start with raw data and a text file containing corresponding sample annotations from either a single or multiple studies. AGA performs all necessary normalization and batch correction, and then enables the user to interactively determine the samples to contrast in the analysis based on the sample annotations. AGA is implemented in R to facilitate adaptation of state-of-the art genomics analysis techniques. Linking R to a web browser-based interface through RStudio’s shiny also facilitates collaborative analyses in research teams with diverse bioinformatics expertise.

AGA bridges the gap between interactive and reproducible analyses for several platforms, including expression arrays, methylation arrays, and processed RNAseq data. Through the interface, the user determines the size and scope of the analyses. AGA first performs data normalization, including the ComBat6 and SVA8 batch correction algorithms to enable comparison across multiple datasets for non-methylation platforms. The software then performs differential analysis15, and gene set analyses1,15 based upon defined sample groups. Users obtain standard visualization of genomics data, including hierarchical clustering, boxplots and heatmaps as part of the default analysis. Plots and tables summarizing the results from each analysis are customizable through the interface. The figures and tables in AGA are interactive and customizable. In contrast to other point and click software, AGA logs the R code, and exports the workspace with each figure and table, ensuring that each analysis can be reproduced and further customized.

Methods

The AGA application is run through R and interactive through web browsers. AGA is implemented with RStudio’s shiny12, integrating the R code used in the analysis with HTML and JavaScript, for the interactive user interface. Usage requires R version 3.0.1 or higher, and either Mozilla Firefox or Google Chrome, and R packages described in the AGA User’s Manual. The program is divided into seven tabs. Clicking the respective Update button generates the results to be displayed in each tab and clicking the Download buttons save the plots and data.

Data platforms

AGA supports analyses of DNA methylation and gene expression data. Currently, AGA supports DNA methylation analysis on Illumina 450k arrays. It also supports gene expression analysis of any human Affymetrix expression platform, including exon arrays, and normalized gene counts from RNAseq data. Notably, the flexible format for normalized RNAseq data may be adapted to analyze normalized data from other platforms measuring continuous data, many of which we plan to incorporate in future versions of AGA.

Initiation

Users of AGA select to load annotation files and high throughput genomic data from files in a specified directory. AGA accepts raw CEL files and iDat files for Affymetrix and DNA methylation arrays, respectively. It is assumed that normalized RNAseq data are formatted as individual text files for each sample, containing gene names and normalized counts for each sample. More details about the format for each data type are provided in the User’s manual. Sample annotations are specified in a CSV file, whose first column matches the names of the data files. By default, it is assumed the annotation file defines the sample batch; however, this can be updated by editing the annotation files to contain a ‘Batch’ column with unique identifiers for each respective batch within the dataset. Further details about the sample annotations are also provided in the User’s manual.

Sample selection for differential analysis

After loading in the annotation files, AGA users select categories from the annotation for differential expression analysis. AGA automatically groups samples with common levels in each category as groups for differential analysis. Samples may be further subset from the complete dataset from the criteria selected for each group. When selected, AGA updates the display to output the sample size for each group. Samples are set for analysis by clicking the “Run the Analysis!” button. In cases for which samples span multiple batches, the analysis automatically performs ComBat and SVA batch correction protecting for the biological groups in the annotation selected by the user. Help boxes are available to clarify each input field with further details in the User’s manual.

Interactive plots and tables

The Dendrogram Plot tab in displays unsupervised hierarchical clustering based upon the complete correlation between values of genes (rows) and samples (columns). The Heatmap Plot tab provides an interactive Javascript heatmap of the genomic data, allowing users to customize genes plotted and color rows by sample annotations. For both Dendrograms and Heatmaps, an option is available to view the pre-batch corrected data to show the effects of batch on and efficacy of correction of the data. The Gene Box Plot tab creates boxplots to summarize values of a user-selected gene in the selected groups.

The Differential Results tab displays the results from the differential analysis using empirical Bayes moderated t-statistics with the Bio-conductor Package limma15. Statistics are computed on data that have been batch corrected by combining ComBat with SVA, protecting for the biological groups selected for comparison9. The p-values are adjusted utilizing the Benjamini-Hotchberg method for multiple hypothesis testing7. Optionally, gene set statistics can be performed for each gene set defined in Biocarta and Gene Ontology using a Wilcoxon rank-sum test comparing the t-statistics from the most differentially expressed probe for genes in the set to similarly selected t-statistics for genes outside of the set. If selected, results from gene set analysis are displayed in the GSA Results tab.

Example

As an example, we perform analysis on sample datasets containing gene expression of primary head and neck squamous cell carcinoma (HNSCC) tumors. We downloaded measurements from a combination of frozen tumor samples from two distinct studies in GEO available under accession numbers GSE103002 and GSE679111, representing two distinct batches. Raw CEL files and annotation csv files were obtained as described in the User’s manual. We initialize AGA by selecting the directory containing these data. Once loaded, we check the HPV and Tumor.Source.Type columns to group the samples into primary HPV-positive and HPV-negative tumors for differential expression analysis. We then click “Run the Analysis” to normalize the CEL files with fRMA5, batch correct the data with ComBat and SVA, and perform differential expression analysis. The plot in the Dendrogram Plot tab confirms that the batch effects are apparent between these datasets but removed after batch. The heatmap generated in the Heatmap Plot tab (Figure 1) demonstrates that the batch correction nonetheless preserves gene expression difference between HPV-positive and HPV-negative tumors. Moreover, performing differential expression analysis comparing HPV-positive and HPV-negative HNSCC in the “Differential Analysis” tab confirms the well-established overexpression (p=8.74e-9) of CDKN2A (p16) in HPV-positive HNSCC13,14.

7817be69-6936-4da5-a449-321e8e5a3c85_figure1.gif

Figure 1. Heatmap displaying the relative expression of the 150 probes with the lowest p values from the example analysis, including CDKN2A.

Discussion

AGA provides an interface to enable users who may be unfamiliar with R to perform reproducible genomics class comparison analysis. Unlike other automated pipelines, experienced R users can reproduce, extend or modify preliminary analyses. Thus, AGA facilitates collaborations between novice and expert R users for genomics analysis. Future work will extend the AGA pipeline to encode normalization routines to DNA methylation, and analysis routines for other genomics platforms, including copy number data.

Software availability

Source code as at the time of publication

https://gist.github.com/F1000Research/9d2acc6aca8ba2d1cc76

Archived source code as at the time of publication

http://dx.doi.org/10.5281/zenodo.1405618

License

GNU GPL V2

Comments on this article Comments (0)

Version 2
VERSION 2 PUBLISHED 28 Jan 2015
Comment
Author details Author details
Competing interests
Grant information
Copyright
Download
 
Export To
metrics
Views Downloads
F1000Research - -
PubMed Central
Data from PMC are received and updated monthly.
- -
Citations
CITE
how to cite this article
Considine M, Parker H, Wei Y et al. AGA: Interactive pipeline for reproducible genomics analyses [version 1; peer review: 2 approved] F1000Research 2015, 4:28 (https://doi.org/10.12688/f1000research.6030.1)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.
track
receive updates on this article
Track an article to receive email alerts on any updates to this article.

Open Peer Review

Current Reviewer Status: ?
Key to Reviewer Statuses VIEW
ApprovedThe paper is scientifically sound in its current form and only minor, if any, improvements are suggested
Approved with reservations A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approvedFundamental flaws in the paper seriously undermine the findings and conclusions
Version 1
VERSION 1
PUBLISHED 28 Jan 2015
Views
34
Cite
Reviewer Report 22 Jun 2015
Matthew McCall, Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY, USA 
Approved
VIEWS 34
The authors describe a software package for interactive (via a shiny webapp) genomic analysis. By running R behind the scenes, this software addresses a common challenge in genomic data analysis -- the transition from simple initial analyses (typically performed by ... Continue reading
CITE
CITE
HOW TO CITE THIS REPORT
McCall M. Reviewer Report For: AGA: Interactive pipeline for reproducible genomics analyses [version 1; peer review: 2 approved]. F1000Research 2015, 4:28 (https://doi.org/10.5256/f1000research.6456.r8835)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.
  • Author Response 21 Oct 2015
    Michael Considine, Department of Oncology Biostatistics & Bioinformatics, Johns Hopkins University School of Medicine, Baltimore, 21205, USA
    21 Oct 2015
    Author Response
    1) The title of the article is currently too broad -- the software is only able to handle Affymetrix expression arrays, Illumina 450k methylation arrays, and normalized RNA-seq gene counts. ... Continue reading
COMMENTS ON THIS REPORT
  • Author Response 21 Oct 2015
    Michael Considine, Department of Oncology Biostatistics & Bioinformatics, Johns Hopkins University School of Medicine, Baltimore, 21205, USA
    21 Oct 2015
    Author Response
    1) The title of the article is currently too broad -- the software is only able to handle Affymetrix expression arrays, Illumina 450k methylation arrays, and normalized RNA-seq gene counts. ... Continue reading
Views
48
Cite
Reviewer Report 02 Feb 2015
Subha Madhavan, Innovation Center for Biomedical Informatics, Georgetown University, Washington, DC, USA 
Approved
VIEWS 48
The authors have described Automated Genomics Analysis (AGA), an interactive program to analyze high-throughput genomic data sets on a variety of platforms.

The software is implemented in R with web app using Shiny.

Specific comments are noted below:
  1. cBIOPortal is listed as an example for
... Continue reading
CITE
CITE
HOW TO CITE THIS REPORT
Madhavan S. Reviewer Report For: AGA: Interactive pipeline for reproducible genomics analyses [version 1; peer review: 2 approved]. F1000Research 2015, 4:28 (https://doi.org/10.5256/f1000research.6456.r7514)
NOTE: it is important to ensure the information in square brackets after the title is included in all citations of this article.
  • Author Response 21 Oct 2015
    Michael Considine, Department of Oncology Biostatistics & Bioinformatics, Johns Hopkins University School of Medicine, Baltimore, 21205, USA
    21 Oct 2015
    Author Response
    1) cBIOPortal is listed as an example for reducing cost of genomic analysis using AGA. cBioPortal's purpose is to help researchers mine analyzed results and it is available for free ... Continue reading
COMMENTS ON THIS REPORT
  • Author Response 21 Oct 2015
    Michael Considine, Department of Oncology Biostatistics & Bioinformatics, Johns Hopkins University School of Medicine, Baltimore, 21205, USA
    21 Oct 2015
    Author Response
    1) cBIOPortal is listed as an example for reducing cost of genomic analysis using AGA. cBioPortal's purpose is to help researchers mine analyzed results and it is available for free ... Continue reading

Comments on this article Comments (0)

Version 2
VERSION 2 PUBLISHED 28 Jan 2015
Comment
Alongside their report, reviewers assign a status to the article:
Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested
Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.
Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions