cis-X

Last updated: 4 years ago (view history), Time to read: 22 mins
Authors Yu Liu1,2,*,#, Chunliang Li3,*, Shuhong Shen1,4,*, Xiaolong Chen2, Karol Szlachta2, Michael N. Edmonson2, Ying Shao2, Xiaotu Ma2, Judith Hyle3, Shaela Wright3, Bensheng Ju2, Michael C. Rusch2, Yanling Liu2, Benshang Li1,4, Michael Macias2, Liqing Tian2, John Easton2, Maoxiang Qian5, Jun J. Yang5,6,7, Shaoyan Hu8, A. Thomas Look9,10 and Jinghui Zhang2,#
Publication “Discovery of regulatory non-coding variants in individual cancer genomes using cis-X” (in submission)
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Overview

Activating regular variants usually cause the cis-activation of target genes. To find cis-activated genes, allelic specific/imbalance expressions (ASE) and outlier high expression (OHE) signals are used. Variants in the same topologically associated domains with the candidates can then be searched, including structural variants (SV), copy number aberrations (CNA), and single nucleotide variations (SNV) and insertion/deletions (indel).

A transcription factor binding analysis is also done, using motifs from HOCOMOCO v10 models.

cis-X currently only works with hg19 (GRCh37).

Inputs

Name Type Description Example
Sample ID String The ID of the input sample SJALL018373_D1
Disease subtype String The disease name under analysis. Must be either NBL or TALL. TALL
Single nucleotide variants File Tab-delimited file containing raw sequence variants *.txt
CNV/LOH regions File Tab-delimited file containing any aneuploidy region existing in the tumor genome under analysis *.txt
RNA-Seq BAM File BAM file aligned to hg19 (GRCh37) *.bam
RNA-Seq BAM index File BAM index for the given BAM *.bam.bai
Gene expression table File Tab-delimited file containing gene level expressions for the tumor under analysis in FPKM *.txt
Somatic SNV/indels File Tab-delimited file containing somatic SNV/indels in the tumor genome *.txt
Somatic SVs File Tab-delimited file containing somatic acquired structural variants in the tumor genome *.txt
Somatic CNVs File Tab-delimited file containing copy number aberrations in the tumor genome *.txt
CNV/LOH action String The behavior when handling markers in CNV/LOH regions. Can be either keep or drop. [default: keep] drop
Minimum coverage for WGS Integer The minimum coverage in WGS to be included in the analysis [default: 10] 10
Minimum coverage for RNA-Seq Integer The minimum coverage in RNA-Seq to be included in the analysis [default: 10] 5
Candidate FPKM threshold Float The FPKM threshold for the nomination of a cis-activated candidate [default: 5.0] 0.1
User annotations File User applied annotations [optional] *.bed
chr Prefix String Whether the names in the reference sequence dictionary are prefixed with “chr”. Must be either TRUE or FALSE. [default: TRUE] TRUE
TAD annotations File TAD annotations [optional] *.bed

Input file configuration

cis-X requires six tab-delimited input files to be prepared in advance. These files can be uploaded via the command line.

note

Even though CNV/LOH regions, somatic SNV/indels, somatic SVs, and somatic CNVs can be “empty”, using such inputs will produce results with a much higher false positive rate.

Single Nucleotide Variants

A list of single nucleotide markers is a tab-delimited file with the following columns:

  • Chr: chromosome name for the marker
  • Pos: genomic start location for the marker
  • Chr_Allele: reference allele
  • Alternative_Allele: alternative allele
  • reference_tumor_count: reference allele count in the tumor genome
  • alternative_tumor_count: alternative allele count in the tumor genome
  • reference_normal_count: reference allele count in the matched normal genome
  • alternative_normal_count: alternative count in the matched normal genome

This file can be generated with Bambino.

Example
Chr Pos Chr_Allele Alternative_Allele referencetumorcount alternativetumorcount referencenormalcount alternativenormalcount
chr11 61396 TT 0 3 0 10
chr11 72981 T 1 3 2 3

CNV/LOH regions

The CNV/LOH regions are all the genomic regions carrying copy number variations (CNV) or loss of heterozygosity (LOH), which will be filtered out during analysis.

This is a tab-delimited file in the bed format. It must have at least the following three columns:

  • chrom: chromosome name
  • loc.start: genomic start location
  • loc.end: genomic end location

If no CNV/LOH are in the genome under analysis, a file with no rows (but including headers) can be provided.

This file can be generated with CONSERTING.

Example
chrom loc.start loc.end Sample seg.mean LogRatio source
chr9 10712 37855747 SJALL018373_D1 0.471181417 LOH
chr9 20276901 20703900 SJALL018373_D1 -0.978 -5.696 CNV

Gene expression table

The gene expression table is a tab-delimited file containing gene level expressions for the tumor under analysis. The expressions are in FPKM (fragments per kilobase of transcript per million mapped reads).

  • GeneID: gene Ensembl ID
  • GeneName: gene symbol
  • Type: transcript type
  • Status: transcript status (must be KNOWN, NOVEL, or PUTATIVE)
  • Chr: chromosome name
  • Start genomic start location
  • End: genomic end location
  • [SampleID…]: FPKM for the given sample

This file can be generated with the output of HTseq-count preprocessed through mergeData_geneName.pl (available with the distribution of cis-X). The data must be able to match values in the given gene specific reference expression matrices generated from a larger cohort.

Example
GeneID GeneName Type Status Chr Start End SJALL018373_D1
ENSG00000261122.2 5S_rRNA lincRNA NOVEL chr16 34977639 34990886 0.0000
ENSG00000249352.3 7SK lincRNA NOVEL chr5 68266266 68325992 4.5937

Somatic SNV/indels

This is a tab-delimited file containing somatic sequence mutations present in the genome under analysis. It includes both single nucleotide variants (SNV) and small insertion/deletions (indel). The file must have the following columns:

  • chr: chromosome name
  • pos: genomic start location
  • ref: reference nucleotide
  • mutant: mutant nucleotide
  • type: mutation type (must be either snv or indel)

Note that the coordinate used for an indel is after the inserted sequence.

If no SNV/indels are in the sample under analysis, a file with no rows (but including headers) can be provided.

This file can can be created with Bambino and then preprocessed using the steps taken in ”The genetic basis of early T-cell precursor acute lymphoblastic leukaemia“.

Example
chr pos ref mut type
chr1 24782720 G A snv
chr11 82896176 T C snv

Somatic SVs

This is a tab-delimited file containing somatic-acquired structural variants (SV) in the cancer genome. The file must have the following columns:

  • chrA: chromosome name of the left breakpoint
  • posA: genomic location of the left breakpoint
  • ortA: strand orientation of the left breakpoint
  • chrB: chromosome name of the right breakpoint
  • posB: genomic location of the right breakpoint
  • ortB: strand orientation of the right breakpoint

Strand orientations are denoted with a + for a sense or coding strand and - for a antisense or non-coding strand.

If no somatic SVs are in the sample under analysis, a file with no rows (but including headers) can be provided.

This file can be generated by CREST.

Example
chrA posA ortA chrB posB ortB type
chr11 33913169 + chr7 142494049 - CTX
chr11 64219334 + chr2 205042527 - CTX

Somatic CNVs

This is a tab-delimited file containing the genomic regions with somatic-acquired copy number aberrations (CNA) in the cancer genome.

  • chr: chromosome name
  • start: genomic start location
  • end: genomic end location
  • logR: log2 ratio

If no somatic CNVs are in the sample under analysis, a file with no rows (but including headers) can be provided.

This file can be generating by CONSERTING.

Example
chr start end logR
chr9 20276901 20703900 -5.696

Outputs

Name Description
cis-activated candidates cis-activated candidates in the tumor genome under analysis
SV candidates Structural variant (SV) candidates predicted as the causal for the cis-activated genes in the regulatory territory
CNA candidates Copy number aberrations (CNA) predicted as the causal for the cis-activated genes in the regulatory territory
SNV/indel candidates SNV/indel candidates predicted as functional and predicted transcription factors
OHE results Raw outlier high expression (OHE) results
Gene level ASE results Raw gene level allelic specific expression (ASE) results
Single marker ASE results Raw single marker allelic specific expression (ASE) results

Creating a workspace

Before you can run one of our workflows, you must first create a workspace in DNAnexus for the run. Refer to the general workflow guide to learn how to create a DNAnexus workspace for each workflow run.

You can navigate to the Cis-X workflow page here

Uploading Input Files

cis-X requires a total of eight files to be uploaded, as input.

Refer to the general workflow guide to learn how to upload input files to the workspace you just created.

Running the Workflow

Refer to the general workflow guide to learn how to launch the workflow, hook up input files, adjust parameters, start a run, and monitor run progress.

Analysis of Results

Each tool in St. Jude Cloud produces a visualization that makes understanding results more accessible than working with excel spreadsheet or tab delimited files. This is the primary way we recommend you work with your results.

Refer to the general workflow guide to learn how to access these visualizations.

We also include the raw output files for you to dig into if the visualization is not sufficient to answer your research question.

Refer to the general workflow guide to learn how to access raw results files.

Interpreting results

cis-activated candidates

The main result file contains the cis-activated candidates in the tumor genome under analysis.

  • gene: gene accession number (RefSeq ID)
  • gsym: gene symbol
  • chrom: chromosome name
  • strand: strand orientation
  • start: genomic start location
  • end: genomic end location
  • cdsStartStat: coding sequence (CDS) start status
  • cdsEndStat: coding sequence (CDS) end status
  • markers: number of heterozygous markers in this gene
  • ase_markers: number of heterozygous markers showing allelic specific expressions (ASE)
  • average_ai_all: average B-allele frequency (BAF) difference between RNA and DNA for all heterozygous markers
  • average_ai_ase: average BAF difference between RNA and DNA for ASE markers
  • pval_all_markers: p-value for each marker in the ASE test
  • pval_ase_markers: p-value for ASE markers in the ASE test
  • ai_all_markers: BAF difference between RNA and DNA for all heterozygrous markers
  • ai_ase_markers: BAF difference between RNA and DNA for ASE markers
  • comb.pval: combined p-value for the ASE test
  • mean.delta: average BAF difference between RNA and DNA for all markers
  • rawp: raw p-value for the ASE test
  • Bonferroni: adjusted p-value for the ASE test (single-step Bonferroni)
  • ABH: adjusted p-value for the ASE test (Benjamini-Hochberg)
  • FPKM: FPKM value
  • loo.source: which reference expression matrix was used in the outlier high expression (OHE) test
  • loo.cohort.size: number of cases in the reference expression matrix for this gene
  • loo.pval: p-value of the OHE test
  • loo.rank: rank of the case under analysis among the reference cases
  • imprinting.status: imprinting status of the gene
  • candidate.group: status of the gene, combining both ASE and outlier tests

Strand orientations are denoted with a + for a sense or coding strand and - for a antisense or non-coding strand.

Coding sequence status is typically one of “none” (not specified), “unk” (unknown), “incmpl” (incomplete), or “cmpl” (complete).

Example
gene gsym chrom strand start end cdsStartStat cdsEndStat markers ase_markers averageaiall averageaiase pvalallmarkers pvalasemarkers aiallmarkers aiasemarkers comb.pval mean.delta rawp Bonferroni ABH FPKM loo.source loo.cohort.size loo.pval loo.rank imprinting.status candidate.group
NM_145804 ABTB2 chr11 - 34172533 34379555 cmpl cmpl 5 5 0.5 0.500 0.001953125,0.001953125,0.001953125,6.10351562500001e-05,0.000244140625 0.001953125,0.001953125,0.001953125,6.10351562500001e-05,0.000244140625 0.5,0.5,0.5,0.5,0.5 0.5,0.5,0.5,0.5,0.5 0.000644290972057077 0.5 0.000644290972057077 0.632049443587993 0.0110866672927557 7.6776 bi_cohort 40 0.0367241086505276 1 ase_outlier
NM_003189 TAL1 chr1 - 47681961 47698007 cmpl cmpl 2 2 0.482 0.482 6.66361745922277e-28,3.30872245021211e-24 6.66361745922277e-28,3.30872245021211e-24 0.464912280701754,0.5 0.464912280701754,0.5 4.69553625126628e-26 0.482456140350877 4.69553625126628e-26 4.60632106249222e-23 6.11761294450693e-24 8.8168 white_list 167 0.0139385771987089 1 ase_outlier

SV candidates

Structural variant (SV) candidates include candidates predicted as the causal for the cis-activated genes in the regulatory territory.

  • left.candidate.inTAD: cis-activated candidate near the left breakpoint
  • right.candidate.inTAD: cis-activated candidate near the right breakpoint
  • chrA: chromosome name of the left breakpoint
  • posA: genomic location of the left breakpoint
  • ortA: strand orientation of the left breakpoint
  • chrB: chromosome name of the right breakpoint
  • posB: genomic location of the right breakpoint
  • ortB: strand orientation of the right breakpoint
  • type: type of translocation
Example
left.candidate.inTAD right.candidate.inTAD chrA posA ortA chrB posB ortB type
LMO2 chr11 33913169 + chr7 142494049 - CTX

CNA candidates

Copy number aberration (CNA) candidates include candidates predicted as the causal for the cis-activated genes in the regulatory territory.

  • candidate.inTAD: cis-activated candidate by the CNA
  • chr: chromosome name
  • start: genomic start position
  • end: genomic end location
  • logR: log ratio of the CNA

SNV/indel candidates

SNV/indel candidates include predicted candidates as functional and predicted transcription factors. The mutations are also annotated for known regulatory elements reported by the NIH Roadmap Epigenomics Project by collecting 111 cell lines.

  • chrom: chromosome name
  • pos: genomic start position
  • ref: reference allele genotype
  • mut: mutant allele genotype
  • type: mutation type (either snv or indel)
  • target: cis-activated candidate
  • dist: distance between the mutation and transcription start sites of the target gene
  • tf: transcription factors predicted to have the binding motif introduced by the mutation
  • EpiRoadmap_enhancer: enhancer regions that overlap with the mutation (from the NIH Roadmap Epigenomics Project)
  • EpiRoadmap_promoter: promoter regions that overlap with the mutation (from the NIH Roadmap Epigenomics Project)
  • EpiRoadmap_dyadic: dyadic regions that overlap with the mutation (from the NIH Roadmap Epigenomics Project)
Example
chrom pos ref mut type target dist tf EpiRoadmap_enhancer EpiRoadmap_promoter EpiRoadmap_dyadic
chr1 47696311 C T snv TAL1 1696 BCL11A,CEBPG,PBX2,YY1,ZBTB4 Brain,Digestive,ES-deriv,ESC,HSC & B-cell,Heart,Muscle,Other,Sm. Muscle,iPSC

OHE results

OHE results are the raw results for the outlier expression test.

  • Gene: gene symbol
  • fpkm.raw: FPKM value
  • size.bi: number of cases in the bi-allelic reference cohort
  • p.bi: p-value in the outlier test using the bi-allelic reference cohort
  • rank.bi: rank of the expression level in the case under analysis compared to the bi-allelic reference cohort
  • size.cohort: number of cases in the entire reference cohort
  • p.cohort: p-value in the outlier test using the entire reference cohort
  • rank.cohort: rank of the expression level in the case under analysis compared to the entire reference cohort
  • size.white: number of cases in the whitelist reference cohort
  • p.white: p-value in the outlier test using the whitelist reference cohort
  • rank.white: rank of the expression level in the case under analysis compared to the whitelist reference cohort
Example
Gene fpkm.raw size.bi p.bi rank.bi size.cohort p.cohort rank.cohort size.white p.white rank.white
7SK 4.5937 na na na 264 0.716284011918374 162 na na na
A1BG 0.2312 24 0.900132642257996 21 264 0.84055666600945 222 na na na

Gene level ASE results

Gene level ASE results are the raw results from the gene level ASE test.

  • gene: gene accession number (RefSeq ID)
  • gsym: gene symbol
  • chrom: chromosome name
  • strand: strand orientation
  • start: genomic start location
  • end: genomic end location
  • cdsStartStat: coding sequence (CDS) start status
  • cdsEndStat: coding sequence (CDS) end status
  • markers: number of heterozygous markers in this gene
  • ase_markers: number of heterozygous markers showing allelic specific expressions (ASE)
  • average_ai_all: average B-allele frequency (BAF) difference between RNA and DNA for all heterozygous markers
  • average_ai_ase: average BAF difference between RNA and DNA for ASE markers
  • pval_all_markers: p-value for each marker in the ASE test
  • pval_ase_markers: p-value for ASE markers in the ASE test
  • ai_all_markers: BAF difference between RNA and DNA for all heterozygrous markers
  • ai_ase_markers: BAF difference between RNA and DNA for ASE markers
  • comb.pval: combined p-value for the ASE test
  • mean.delta: average BAF difference between RNA and DNA for all markers
  • rawp: raw p-value for the ASE test
  • Bonferroni: adjusted p-value for the ASE test (single-step Bonferroni)
  • ABH: adjusted p-value for the ASE test (Benjamini-Hochberg)
Example
gene gsym chrom strand start end cdsStartStat cdsEndStat markers ase_markers averageaiall averageaiase pvalallmarkers pvalasemarkers aiallmarkers aiasemarkers comb.pval mean.delta rawp Bonferroni ABH
NM_024684 AAMDC chr11 + 77532207 77583398 cmpl cmpl 2 0 0.079 na 0.924775093657227,0.0331439677875056 na 0.00892857142857145,0.149122807017544 na 0.175073458624837 0.0790256892230577 0.175073458624837 1 0.480780882445856
NM_015423 AASDHPPT chr11 + 105948291 105969419 cmpl cmpl 2 0 0.023 na 0.749258624760841,1 na 0.0384615384615384,0.00769230769230766 na 0.86559726476049 0.023076923076923 0.86559726476049 1 0.873257417545981

Single marker ASE results

Single marker ASE results are the raw results from the single marker ASE test.

  • chrom: chromosome name
  • pos: genomic start position
  • ref: reference allele genotype
  • mut: non-reference allele genotype
  • cvg_wgs: coverage of the marker from the whole genome sequence (WGS)
  • mut_freq_wgs: non-reference allele fraction in the WGS
  • cvg_rna: coverage of the marker from the RNA-Seq
  • mut_freq_rna: non-reference allele fraction in the RNA-Seq
  • ref.1: read count of the reference allele in the RNA-Seq
  • var: read count of the non-reference allele in the RNA-Seq
  • pvalue: p-value from the binomial test
  • delta.abs: absolute difference of the non-reference allele fraction between the WGS and RNA-Seq
Example
chrom pos ref mut cvg_wgs mutfreqwgs cvg_rna mutfreqrna ref.1 var pvalue delta.abs
chr11 204147 G A 36 0.472 85 0.553 38 47 0.385669420119278 0.0529411764705883
chr11 205198 C A 23 0.522 83 0.313 57 26 0.000877551780002863 0.186746987951807

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Footnotes

1 Pediatric Translational Medicine Institute, Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China

2 Department of Computational Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA

3 Department of Tumor Cell Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA

4 Key Laboratory of Pediatric Hematology & Oncology Ministry of Health, Department of Hematology & Oncology, Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China

5 Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA

6 Hematological Malignancies Program, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA

7 Department of Oncology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA

8 Children’s Hospital of Soochow University, Suzhou, Jiangsu, China

9 Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA

10 Division of Pediatric Hematology-Oncology, Boston Children’s Hospital, MA 02115, USA

* Contributed equally to this work.

# Correspondence should be addressed to Y.L. (liuyu@scmc.com.cn) or J.Z. (jinghui.zhang@stjude.org).