bilevelAnalysisGeneset {BLMA} | R Documentation

## Bi-level meta-analysis – applied to geneset enrichment analysis

### Description

Perform a bi-level meta-analysis in conjunction with geneset enrichment methods (ORA/GSA/PADOG) to integrate multiple gene expression datasets.

### Usage

    bilevelAnalysisGeneset(gslist, gs.names, dataList, groupList, splitSize = 5,
      metaMethod = addCLT, enrichment = "ORA", pCutoff = 0.05,
      percent = 0.05, mc.cores = 1, ...)

### Arguments

`gslist` | a list of gene sets.
`gs.names` | names of the gene sets.
`dataList` | a list of datasets to be combined. Each dataset is a data frame where the rows are the gene IDs and the columns are the samples.
`groupList` | a list of vectors. Each vector represents the phenotypes of the corresponding dataset in dataList. The elements of each vector are either 'c' (control) or 'd' (disease).
`splitSize` | the minimum number of disease samples in each split dataset. splitSize should be at least 3. By default, splitSize=5
`metaMethod` | the method used to combine p-values. This should be one of addCLT (additive method [1]), fisherMethod (Fisher's method [5]), stoufferMethod (Stouffer's method [6]), max (maxP method [7]), or min (minP method [8])
`enrichment` | the method used for enrichment analysis. This should be one of "ORA", "GSA", or "PADOG". By default, enrichment is set to "ORA".
`pCutoff` | cutoff p-value used to identify differentially expressed (DE) genes. This parameter is used only when the enrichment method is "ORA". By default, pCutoff=0.05 (five percent)
`percent` | percentage of genes with highest foldchange to be considered as differentially expressed (DE). This parameter is used when the enrichment method is "ORA". By default percent=0.05 (five percent). Please note that only genes with p-value less than pCutoff will be considered
`mc.cores` | the number of cores to be used in parallel computing. By default, mc.cores=1
`...` | additional parameters of the GSA/PADOG functions

### Details

The bi-level framework combines the datasets at two levels: an intra- experiment analysis, and an inter-experiment analysis [1]. At the intra-level analysis, the framework splits a dataset into smaller datasets, performs enrichment analysis for each split dataset (using ORA [2], GSA [3], or PADOG [4]), and then combines the results of these split datasets using metaMethod. At the inter-level analysis, the results obtained for individual datasets are combined using metaMethod

### Value

A data frame (rownames are geneset/pathway IDs) that consists of the following information:

- Name: name/description of the corresponding pathway/geneset

- Columns that include the pvalues obtained from the intra-experiment analysis of individual datasets

- pBLMA: p-value obtained from the inter-experiment analysis using addCLT

- rBLMA: ranking of the geneset/pathway using addCLT

- pBLMA.fdr: FDR-corrected p-values

### Author(s)

Tin Nguyen and Sorin Draghici

### References

[1] T. Nguyen, R. Tagett, M. Donato, C. Mitrea, and S. Draghici. A novel bi-level meta-analysis approach – applied to biological pathway analysis. Bioinformatics, 32(3):409-416, 2016.

[2] S. Draghici, P. Khatri, R. P. Martin, G. C. Ostermeier, and S. A. Krawetz. Global functional profiling of gene expression. Genomics, 81(2):98-104, 2003.

[3] B. Efron and R. Tibshirani. On testing the significance of sets of genes. The Annals of Applied Statistics, 1(1):107-129, 2007.

[4] A. L. Tarca, S. Draghici, G. Bhatti, and R. Romero. Down-weighting overlapping genes improves gene set analysis. BMC Bioinformatics, 13(1):136, 2012.

[5] R. A. Fisher. Statistical methods for research workers. Oliver & Boyd, Edinburgh, 1925.

[6] S. Stouffer, E. Suchman, L. DeVinney, S. Star, and J. Williams, RM. The American Soldier: Adjustment during army life, volume 1. Princeton University Press, Princeton, 1949.

[7] L. H. C. Tippett. The methods of statistics. The Methods of Statistics, 1931.

[8] B. Wilkinson. A statistical consideration in psychological research. Psychological Bulletin, 48(2):156, 1951.

### See Also

`bilevelAnalysisPathway`, `phyper`, `GSA`, `padog`

### Examples

    # load KEGG pathways and create gene sets
    x <- loadKEGGPathways()
    gslist <- lapply(x$kpg,FUN=function(y){return (nodes(y));})
    gs.names <- x$kpn[names(gslist)]

    # load example data
    dataSets <- c("GSE17054", "GSE57194", "GSE33223", "GSE42140")
    data(list=dataSets, package="BLMA")
    names(dataSets) <- dataSets
    dataList <- lapply(dataSets, function(dataset) get(paste0("data_", dataset)))
    groupList <- lapply(dataSets, function(dataset) get(paste0("group_", dataset)))
    # perform bi-level meta-analysis in conjunction with ORA
    ORAComb <- bilevelAnalysisGeneset(gslist, gs.names, dataList, groupList, enrichment = "ORA")
    head(ORAComb[, c("Name", "pBLMA", "pBLMA.fdr", "rBLMA")])

    # perform bi-level meta-analysis in conjunction with GSA
    GSAComb <- bilevelAnalysisGeneset(gslist, gs.names, dataList, groupList, enrichment = "GSA", nperms = 200, random.seed = 1)
    head(GSAComb[, c("Name", "pBLMA", "pBLMA.fdr", "rBLMA")])

    # perform bi-level meta-analysi in conjunction with PADOG
    set.seed(1)
    PADOGComb <- bilevelAnalysisGeneset(gslist, gs.names, dataList, groupList, enrichment = "PADOG", NI=200)
    head(PADOGComb[, c("Name", "pBLMA", "pBLMA.fdr", "rBLMA")])

[Package BLMA version 1.8.0 Index]