Correlations between copy number and mRNA expression
Brain Lower Grade Glioma (Primary solid tumor)
22 February 2013  |  analyses__2013_02_22
Maintainer Information
Citation Information
Maintained by John Zhang (MD Anderson Cancer Center)
Cite as Broad Institute TCGA Genome Data Analysis Center (2013): Correlations between copy number and mRNA expression. Broad Institute of MIT and Harvard. doi:10.7908/C1Q23XFD
Overview
Introduction

A TCGA sample is profiled to detect the copy number variations and expressions of genes. This pipeline attempts to correlate copy number and expression data of genes across samples to determine if the copy number variations also result in differential expressions. This report contains the calculated correlation coefficients based on measurements of genomic copy number (log2) values and intensity of the expressions of the corresponding feature across patients. High positive/low negative correlation coefficients indicate that genomic alterations result in differences in the expressions of mRNA the genomic regions transcribe.

Summary

The correlation coefficients in 10, 20, 30, 40, 50, 60, 70, 80, 90 percentiles are -0.1572, -0.0457, 0.0402, 0.1179, 0.19345, 0.2741, 0.36144, 0.46754, 0.6038, respectively.

Results
Correlation results

Number of genes and samples used for the calculation are shown in Table 1. Figure 1 shows the distribution of calculated correlation coefficients and quantile-quantile plot of the calculated correlation coefficients against a normal distribution. Table 2 shows the top 20 features ordered by the value of correlation coefficients.

Table 1.  Counts of mRNA and number of samples in copy number and expression data sets and common to both

Category Copy number Expression Common
Sample 220 27 27
Genes 24174 17815 15702

Figure 1.  Summary figures. Left: histogram showing the distribution of the calculated correlations across samples for all Genes. Right: QQ plot of the calculated correlations across samples. The QQ plot is used to plot the quantiles of the calculated correlation coefficients against that derived from a normal distribution. Points deviating from the blue line indicate deviation from normality.

Table 2.  Get Full Table Top 20 features (defined by the feature column) ranked by correlation coefficients

feature r p-value q-value chrom start end geneid
APITD1 0.9514 2.68673971959288e-14 2.4716201232425e-10 378708 1p36.22 0.004 0.457
MRPS15 0.9485 5.52891066263328e-14 2.54311326730323e-10 64960 1p34.3 0.004 0.457
POP4 0.9442 1.46771483855446e-13 4.50066364039475e-10 10775 19q12 0.008 0.020
CCDC97 0.9367 6.7745808962627e-13 1.55803987520927e-09 90324 19q13.2 0.008 0.020
LSM10 0.9316 1.71951342053944e-12 3.1636737577504e-09 84967 1p34.3 0.004 0.457
CSDE1 0.9302 2.21489493412719e-12 3.39592434288484e-09 7812 1p13.2 0.003 0.445
PPP1R15B 0.9286 2.91744406410999e-12 3.83407518291419e-09 84919 1q32.1 0.003 0.442
GPBP1L1 0.9257 4.72533123740959e-12 5.10529137302266e-09 60313 1p34.1 0.004 0.453
TMEM41B 0.9254 4.99467134318365e-12 5.10529137302266e-09 440026 11p15.4 -0.015 -0.011
PAF1 0.9147 2.49755771619675e-11 2.29758538398609e-08 54623 19q13.2 0.008 0.020
RRAGA 0.9136 2.9194646700148e-11 2.44155586344138e-08 10670 9p22.1 0.000 0.001
PEX14 0.9078 6.38133990094047e-11 4.61198344141063e-08 5195 1p36.22 0.004 0.457
DNAJC16 0.9076 6.51740883483853e-11 4.61198344141063e-08 23341 1p36.21 0.004 0.457
ZNF790 0.9057 8.31517077415356e-11 5.34872212411403e-08 388536 19q13.12 0.008 0.020
EIF3I 0.9053 8.72137917440341e-11 5.34872212411403e-08 8668 1p35.1 0.004 0.457
NRD1 0.9027 1.20599086272932e-10 6.63258919628582e-08 4898 1p32.3 0.004 0.445
PARP1 0.9025 1.24091403819193e-10 6.63258919628582e-08 142 1q42.12 0.003 0.442
TMEM147 0.9021 1.29777522062113e-10 6.63258919628582e-08 10430 19q13.12 0.008 0.020
FKBP4 0.9011 1.46869405526218e-10 7.11105213543994e-08 2288 12p13.33 0.068 0.002
RPP38 0.9 1.68679292755769e-10 7.75868111282186e-08 10557 10p13 -0.004 -0.585
Methods & Data
Input

Gene level (TCGA Level III) expression data and copy number data of the corresponding loci derived by using the CNTools package of Bioconductor were used for the calculations. Pearson correlation coefficients were calculated for each pair of genes shared by the two data sets across all the samples that were common.

Correlation across sample

Pairwise correlations between the log2 copy numbers and expressions of each gene across samples were calculated using Pearson correlation.

Download Results

This is an experimental feature. The full results of the analysis summarized in this report can be downloaded from the TCGA Data Coordination Center.