avs.vse: Variant set enrichment (VSE) analysis.

Description Usage Arguments Author(s) See Also Examples

Description

The VSE method tests the enrichment of an AVS for a particular trait in a genomic annotation.

Usage

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avs.vse(object, annotation, maxgap=0, pValueCutoff=0.05, boxcox=TRUE, 
lab="annotation", glist=NULL, minSize=100, verbose=TRUE)

Arguments

object

an object. When this function is implemented as the S4 method of class AVS-class, this argument is an object of class 'AVS'.

annotation

a data frame with genomic annotations listing chromosome coordinates to which a particular property or function has been attributed. It should include the following columns: <CHROM>, <START>, <END> and <ID>. The <ID> column can be any genomic identifier, while values in <CHROM> should be listed in ['chr1', 'chr2', 'chr3' ..., 'chrX']. Both <START> and <END> columns correspond to chromosome positions mapped to the human genome assembly used to build the AVS object (see avs.preprocess.LDHapMapRel27).

maxgap

a single integer value specifying the max distant (kb) between the AVS and the annotation used to compute the enrichment analysis.

pValueCutoff

a single numeric value specifying the cutoff for p-values considered significant.

boxcox

a single logical value specifying to use Box-Cox procedure to find a transformation of the null that approaches normality (when boxcox=TRUE) or not (when boxcox=FALSE). See powerTransform and bcPower.

lab

a single character value specifying a name for the annotation dataset (this option is overrided if 'glist' is used).

glist

an optional list with character vectors mapped to the 'annotation' data via <ID> column. This option can be used to run a batch mode for gene sets and regulons.

minSize

if 'glist' is provided, this argument is a single integer or numeric value specifying the minimum number of elements for each gene set in the 'glist'. Gene sets with fewer than this number are removed from the analysis.

verbose

a single logical value specifying to display detailed messages (when verbose=TRUE) or not (when verbose=FALSE).

Author(s)

Mauro Castro

See Also

AVS-class

Examples

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## Not run: 
# This example requires the RTNdata package! (currently available under request)
library(RTNdata.LDHapMapRel27)
library(Fletcher2013b)
library(TxDb.Hsapiens.UCSC.hg18.knownGene)

##################################################
### Build AVS and random AVSs (mapped to hg18)
##################################################

#--- step 1: load 'risk SNPs' data (e.g. BCa risk SNPs from the GWAS catalog)
data(bcarisk, package="RTNdata.LDHapMapRel27")

#--- step 2: build an AVS and 1000 matched random AVSs for the input 'risk SNPs'
bcavs <- avs.preprocess.LDHapMapRel27(bcarisk, nrand=1000)

##################################################
### Example of VSE analysis for ERa and FOXA1 
### cistromes (one genomic annotation each time)
##################################################

#--- step 1: load a precomputed AVS (same 'bcavs' object as above!)
data(bcavs, package="RTNdata.LDHapMapRel27")

#--- step 2: load cistrome data from the Fletcher2013b package
#NOTE: Fletcher2013b is a large data package, but only two 'bed files' 
#are used to illustrate this analysis (ESR1bdsites and FOXA1bdsites). 
#these bed files provide ERa and FOXA1 binding sites mapped by 
#ChIP-seq experiments
data(miscellaneous)

#--- step 3: run the avs.vse pipeline
bcavs <- avs.vse(bcavs, annotation=ESR1bdsites$bdsites, pValueCutoff=0.001, lab="ERa")
bcavs <- avs.vse(bcavs, annotation=FOXA1bdsites$bdsites, pValueCutoff=0.001, lab="FOXA1")

#--- step 4: generate the VSE plots
avs.plot2(bcavs,"vse",height=2.2)

##################################################
### Example of VSE analysis for sets of genomic 
### annotations (e.g. regulons, gene sets, etc.)
##################################################

#--- step 1: load the precomputed AVS (same 'bcavs' object as above!)
data("bcavs", package="RTNdata.LDHapMapRel27")

#--- step 2: load genomic annotation for all genes
genemap <- as.data.frame(genes(TxDb.Hsapiens.UCSC.hg18.knownGene))
genemap <- genemap[,c("seqnames","start","end","gene_id")]
colnames(genemap) <- c("CHROM","START","END","ID")

#--- step 3: load a TNI object, or any other source of regulons (e.g. gene sets)
#--- and prepare a gene set list (gene ids should be the same as in the 'genemap' object)
data("rtni1st")
glist <- tni.get(rtni1st,what="refregulons",idkey="ENTREZ")
glist <- glist[ c("FOXA1","GATA3","ESR1") ] #reduce the list just for demonstration!

#--- step 4: run the avs.vse pipeline
bcavs<-avs.vse(bcavs, annotation=genemap, glist=glist, pValueCutoff=0.05)

#--- step 5: generate the VSE plots
avs.plot2(bcavs,"vse",height=2.5)

### NOTE REGARDING THIS EXAMPLE ####
#- This example is for demonstration purposes only;
#- we recommend using the EVSE/eQTL approach when analysing genes/regulons.
#- Also, the AVS object here is not the same as the one used in the study that  
#- extended the method (doi:10.1038/ng.3458), so the results are not comparable;
#- (here fewer risk SNPs are considered, and without the eQTL step).
####################################


## End(Not run)

RTN documentation built on May 20, 2017, 10:08 p.m.

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