CGHnormaliter (version 1.26.0)

CGHnormaliter: Iterative normalization of aCGH data

Description

Implementation of an iterative algorithm for normalization of aCGH data displaying imbalanced aberrations.

Usage

CGHnormaliter(data, nchrom = 24, cellularity = 1, max.losses = 0.3, plot.MA = TRUE, ...)

Arguments

data

either a dataframe or character string containing a filename. See section Details for the format.

nchrom

number of chromosomes.

cellularity

vector of cellularities ranging from 0 to 1 to define the contamination of your sample with healthy cells (1 = no contamination). See Details for more information.

max.losses

vector of maximum fraction of losses in your samples, ranging from 0 to 1. In case this fraction is exceeded after calling, losses are deemed normals and centralization will be around the (lower) peak at the left of the log2 ratio distribution. See Details for more information.

plot.MA

logical. If ‘plot.MA = TRUE’, MA-plots before and after normalization are generated of each sample. The plots are saved into a PDF file.

...

arguments for segment (from package DNAcopy) and/or CGHcall.

Value

This function returns a matrix of objects of class cghCall with dimension (number of clones) * (number of samples). Each object contains the following components (See section Examples on how to access them):

normalized data

A matrix with the normalized log2 intensity ratios for each profile.

segments

A matrix with the segments for each profile.

calls

A data.frame with the calls for each profile. Values are -1 (loss), 0 (normal) or 1 (gain).

probabilities

A data.frame with 3 columns of probe information (name, chromosome and position), followed by 3 columns with aberration probabilities for each sample.

Details

The input should be either a data.frame or the file name of a tabseparated text file (text files must contain a header). The first four columns should contain the name, chromosome and the start and end position in bp for each array target respectively. The position columns must contain numbers only. Following these are two columns with the raw test and reference intensities for each of your samples. These intensities must be numeric as well. If the input type is a text file, missing values should be represented as 'NA' or an empty field. The cellularity and max.losses parameters should both be a vector of length n where n is the number of samples in your dataset. Each vector is recycled if there are not enough values in it, or truncated if there are too many. There is a CGHnormaliter.write.table method that prints the results in a tabular format.

References

Bart P.P. van Houte, Thomas W. Binsl, Hannes Hettling, Walter Pirovano and Jaap Heringa. CGHnormaliter: an iterative strategy to enhance normalization of array CGH data with imbalanced aberrations. BMC Genomics, 10:401, 2009.

Examples

  data(Leukemia)
  ## Normalize the raw intensity values of the first 4 chromosomes.
  result <- CGHnormaliter(Leukemia, nchrom=4)
  ## Get the normalized log2 intensity ratios, segments and calls
  normalized.data <- copynumber(result)
  segmented.data <- segmented(result)
  called.data <- calls(result)
  ## Plot the normalization result of sample 2
  plot(result[, 2])
  ## Write the normalized log2 intensity ratios to file
  CGHnormaliter.write.table(result)