dmrscan {DMRScan} | R Documentation

## DMR Scan function

### Description

DMR Scan function

### Usage

    dmrscan(observations, windowSize, windowThreshold = NULL, chr = NULL,
      pos = NULL, maxGap = 500, ...)

### Arguments

`observations` | An object of either; `GRangesList` made by `makeCpGregions`, a vector of the test statistic, a `GRanges` object, or a "minfi" object (soon to be supported).
`windowSize` | A sequence of windowSizes for the slidingWindow. Must be an integer vector, with equal length as the number of windows.
`windowThreshold` | Optional argument with corresponding cut-off for each window. Will be estimated if not supplied.
`chr` | A vector of chromosomal position. Only used when the observations vector is a matrix of test statistic.
`pos` | A vector of genomic coordinates for the CpGs to match the chr argument
`maxGap` | The maximum allowed gap between two CpGs within the same region.
`...` | Optional arguments to be passed to `estimateThreshold`, if no grid is specified.

### Value

An object of type `GRanges` with significantly differentially

### Examples

    ## methylation data from chromosome 22
    data(DMRScan.methylationData)
    ## phenotype (end-point for methylation data)

    data(DMRScan.phenotypes)

    ## Test for an association between phenotype and methylation
    test.statistics <- apply(DMRScan.methylationData,1,function(x,y)
      summary(glm(y ~ x, family = binomial(link = "logit")))$coefficients[2,3],
                                                       y = DMRScan.phenotypes)
    ## Set chromosomal position to each test-statistic
    positions <- data.frame(matrix(as.integer(unlist(strsplit(names(test.statistics),
                                   split="chr|[.]"))), ncol = 3, byrow = TRUE))[,-1]
    ## Set clustering features
    min.cpg <- 4  ## Minimum number of CpGs in a tested cluster
    ## Maximum distance (in base-pairs) within a cluster
    ## before it is broken up into two separate cluster
    max.gap <- 750

    ## Identify all clusters, and generate a list for each cluster
    regions <- makeCpGregions(observations = test.statistics,
                              chr = positions[,1], pos = positions[,2],
                              maxGap = max.gap, minCpG = min.cpg)
    ## Number of CpGs in the slidingWindows, can be either a single number
    ## or a sequence of windowSizes
    windowSizes <- 3:7
    nCpG        <- sum(sapply(regions,length)) ## Number of CpGs to be tested

    # Estimate the windowThreshold, based on the number of CpGs and windowSizes
    windowThresholds <- estimateWindowThreshold(nProbe = nCpG,
                   windowSize = windowSizes, method = "sampling", mcmc = 10000)
    ## Run the slidingWindow
    DMRScanResults   <- dmrscan(observations = regions,
                                windowSize = windowSizes,
                                windowThreshold = windowThresholds)
    ## Print the result
    print(DMRScanResults)

[Package DMRScan version 1.14.0 Index]