HMMcopy-package {HMMcopy} | R Documentation

## Bias-free copy number estimation and robust CNA detection in tumour samples from WGS HTS data

### Description

HMMcopy is a package for making bias-free copy number estimation by correcting for GC-content and mappability bias in HTS readcounts. It also contains an implementation of the Hidden Markov Model to robustly segment a copy number profile into non-overlapping segments predicted to be of the same copy number state, and attributes a biological copy number aberration events to the segments.

### Details

HMMcopy takes as input WIG format files generated by fast C++ tools distributed as part of the HMMcopy Suite, namely readcount, GC-content and mappability values for non-overlapping fixed width “bins” across the reference genome of interest. It then uses a filtering and LOESS model to correct the GC-content and mappability biases observed in the readcounts (Benjamini and Speed, 2012), and uses the corrected readcounts as a proxy of copy number. The resultant copy number profile is then segmented with a six state Hidden Markov Model, with a handful of quick visualization functions for quick viewing.

Package: | HMMcopy
Type: | Package
Version: | 0.1.0
Date: | 2011-09-06
License: | GPL-3

`example("HMMcopy-package")` for quick tour of functionality and visualization

`vignette("HMMcopy")` for detailed example

### Author(s)

Daniel Lai, Gavin Ha, Sohrab Shah

Maintainer: Daniel Lai <jujubix@cs.ubc.ca> and Gavin Ha <gha@bccrc.ca>

### References

Yuval Benjamini and Terence P Speed. Summarizing and correcting the gc content bias in high-throughput sequencing. Nucleic Acids Res, 40(10):e72, May 2012.

### Examples

    # Read WIG file input
    rfile <- system.file("extdata", "tumour.wig", package = "HMMcopy")
    gfile <- system.file("extdata", "gc.wig", package = "HMMcopy")
    mfile <- system.file("extdata", "map.wig", package = "HMMcopy")
    uncorrected_reads <- wigsToRangedData(rfile, gfile, mfile)

    # Correct reads into copy number
    corrected_copy <- correctReadcount(uncorrected_reads)

    # Segment copy number profile
    segmented_copy <- HMMsegment(corrected_copy)

    # Visualize one at a time
    par(ask = TRUE)
    plotBias(corrected_copy)
    plotCorrection(corrected_copy)
    plotSegments(corrected_copy, segmented_copy)

[Package HMMcopy version 1.34.0 Index]