differentiallyExpressed {transcriptogramer} | R Documentation

## Identify which genes are differentially expressed

### Description

This method uses the limma package to identify which genes are differentially expressed, meeting the `pValue` requirement, for the contrast "case-control". The `levels` lenght must be equal to the number of samples present in the transcriptogramS2 slot of the `object`, and its contents is related to the order that the samples appear. FALSE must be used to indicate case samples, and TRUE to indicate control samples. If `species` is NULL, no translation will be done, if `species` is a character, the biomaRt package will be used to translate the ENSEMBL Peptide ID to Symbol (Gene Name), and if `species` is a data.frame, it will be used instead. If the translation fail for some protein, its ENSEMBL Peptide ID will be present into the Symbol column. This method also groups the proteins detected as differentially expressed in clusters, and plots a graphical representation of the groupings.

### Usage

    differentiallyExpressed(object, levels, pValue = 0.05, species = NULL,
      adjustMethod = "BH", trend = FALSE, title = "Differential expression")

    ## S4 method for signature 'Transcriptogram'
    differentiallyExpressed(object, levels,
      pValue = 0.05, species = NULL, adjustMethod = "BH", trend = FALSE,
      title = "Differential expression")

### Arguments

`object` | An object of class Transcriptogram.
`levels` | A logical vector that classify the columns, referring to samples, of the transcriptogramS2 slot of the `object`. FALSE must be used to indicate case samples, and TRUE to indicate control samples.
`pValue` | A numeric value between 0 and 1 giving the required family-wise error rate or false discovery rate, the default value is 0.05.
`species` | If not NULL, a character string that will be used, ignoring case sensitivity, to translate the ENSEMBL Peptide ID to Symbol (Gene Name); or a data.frame containing two columns, the first one with ENSEMBL Peptide IDs (character), which may, or not, to contain the taxonomy ID of the species as prefix, and the second containing its respective Symbol (character).
`adjustMethod` | Character string specifying p-value adjustment method, the possible values are 'none', 'BH', 'fdr' (equivalent to 'BH'), 'BY' and 'holm', the default value for this argument is 'BH'.
`trend` | Logical value, set as TRUE to use the limma-trend approach for RNA-Seq, the default value of this argument is FALSE.
`title` | An overall title for the plot, the default value of this argument is "Differential expression"

### Value

This method creates a data.frame to feed the DE slot of an object of class Transcriptogram. This data.frame of differentially expressed proteins contains the log2-fold-change, the p-values and an integer number that indicates if the protein is downregulated or upregulated.

### Author(s)

Diego Morais

### See Also

transcriptogramPreprocess, GSE9988, GPL570, Hs900, association, DEsymbols, transcriptogramStep1, transcriptogramStep2

### Examples

    transcriptogram <- transcriptogramPreprocess(association, Hs900, 50)
    ## Not run:
    transcriptogram <- transcriptogramStep1(transcriptogram, GSE9988, GPL570)
    transcriptogram <- transcriptogramStep2(transcriptogram)
    levels <- c(rep(FALSE, 3), rep(TRUE, 3))
    transcriptogram <- differentiallyExpressed(transcriptogram, levels, 0.01)

    ## translating ENSEMBL Peptide IDs to Symbols
    transcriptogram <- differentiallyExpressed(transcriptogram, levels, 0.01,
    "Homo sapiens")

    ## these calls also works
    transcriptogram <- differentiallyExpressed(transcriptogram, levels, 0.01,
    "H sapiens")

    transcriptogram <- differentiallyExpressed(transcriptogram, levels, 0.01,
    DEsymbols)

    ## End(Not run)

[Package transcriptogramer version 1.2.1 Index]