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Transcriptional Characterization of Glioma Neural Stem Cells Diva ...

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5.3 Differential Gene Expression Methods<br />

"scale" method in the package limma [466]. Replicate arrays were averaged<br />

and the genome (GRCh37) segmented into regions with different copy number<br />

using the circular binary segmentation algorithm in the Bioconductor package<br />

DNAcopy [510], with the option undo.SD set to 1. Aberrations were called<br />

using the package CGHcall [503] [37] with the option nclass set to 4. CGH<br />

data are available from ArrayExpress [28] under accession E-MTAB-972.<br />

5.3 Differential Gene Expression<br />

We called the differentially expressed genes with the Bioconductor package<br />

DESeq that uses pseudo reference-based normalization [21]. DESeq compares<br />

sequencing-derived expression pr<strong>of</strong>iles using a method that is able to account<br />

for large variation between biological replicates, as can be expected with can-<br />

cer samples. The R code that generated the differential expression calls is<br />

reported below, with ## signs indicating a comment:<br />

## Define auxiliary functions<br />

read.gns.counts

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