The ENCODE Blacklist: Identification of Problematic Regions of the Genome

Functional genomics assays based on high-throughput sequencing greatly expand our ability to understand the genome. Here, we define the ENCODE blacklist- a comprehensive set of regions in the human, mouse, worm, and fly genomes that have anomalous, unstructured, or high signal in next-generation sequencing experiments independent of cell line or experiment. The removal of the ENCODE blacklist is an essential quality measure when analyzing functional genomics data.

System Requirements

Hardware Requirements

Generation of the Blacklist requires a significant amount of RAM and disk storage based on the size of the genome analyzed and the number of input data files being processed. For minimal performance, we recommend a computer with the following specs:

RAM: 64+ GB
CPU: 24+ cores, 3.4+ GHz/core

The runtime on this minimal system is approximately 192 CPU hours. Compile time is approximately 1.1 seconds.

Software Requirements

The package development version is tested on Linux operating systems. The developmental version of the package has been tested on the following systems:

Linux: Ubuntu 18.04

Demo

We include a small demo file of an unmapped chromosome from mm10 (chrUn_GL456392). Execution time of this demo is approximately 0.025 seconds. The expected output is a bed annotation of a abnormal region across the entire segment:

cd demo
./Blacklist chrUn_GL456392
chrUn_GL456392  5200    23600   3   18

Installation

Clone a copy of the Blacklist repository and submodules:

git clone --recurse-submodules https://github.com/Boyle-Lab/Blacklist.git

Build bamtools API (please see bamtools documentation for more information) Note: bamtools requires zlib to be installed

cd Blacklist/bamtools/
mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX:PATH=$(cd ..; pwd)/install ..
make
make install
cd ../..

Build Blacklist

make

The blacklist software relies on a certain directory structure relative to the executable to function properly. All input data tracks should sorted and indexed bam files. * Blacklist execuatable * input/ - folder containing all bam and bam.bai files * mappability/ - folder containing all uint8 Umap files

Usage information

The blacklist is built on a per-chromosome or contig level. The following example will build a blacklist for a contig labeled chr1 and output the regions to chr1.bed:

./Blacklist chr1 > chr1.bed

Historical blacklist information

(these lists are also available in the lists/ folder) - HUMAN (hg19/GRCh38): http://mitra.stanford.edu/kundaje/akundaje/release/blacklists/hg38-human/hg38.blacklist.bed.gz ENCODE portal link: https://www.encodeproject.org/annotations/ENCSR636HFF/ (Select GRCh38) - HUMAN (hg19/GRCh37): ENCODE portal link: https://www.encodeproject.org/annotations/ENCSR636HFF/ (Select hg19) UCSC Genome browser track http://genome.ucsc.edu/cgi-bin/hgFileUi?db=hg19&g=wgEncodeMapability README on how this track of generated: http://mitra.stanford.edu/kundaje/akundaje/release/blacklists/hg19-human/hg19-blacklist-README.pdf - MOUSE (mm10): http://mitra.stanford.edu/kundaje/akundaje/release/blacklists/mm10-mouse/mm10.blacklist.bed.gz ENCODE portal link: https://www.encodeproject.org/annotations/ENCSR636HFF/ (Select mm10) - MOUSE (mm9): http://mitra.stanford.edu/kundaje/akundaje/release/blacklists/mm9-mouse/mm9-blacklist.bed.gz - WORM (ce10): http://mitra.stanford.edu/kundaje/akundaje/release/blacklists/ce10-C.elegans/ce10-blacklist.bed.gz - FLY (dm3): http://mitra.stanford.edu/kundaje/akundaje/release/blacklists/dm3-D.melanogaster/dm3-blacklist.bed.gz