Call-sSV Pipeline

• Overview
• How To Run
• Flow Diagram
• Pipeline Steps
• Inputs
• Outputs
• Testing and Validation
  • Test Data Set
  • Performance Validation
  • Validation Tool
• References
• License

Overview:

The call-sSV pipeline calls somatic structural variants utilizing DELLY and Manta. This pipeline requires at least one tumor sample and a matched normal sample. This pipeline is developed using Nextflow, docker and can run either on a single node linux machine or a multi-node HPC Slurm cluster.

How to Run:

Requirements

Currently supported Nextflow versions: v23.04.2

Run steps

Below is a summary of how to run the pipeline. See here for full instructions.

Pipelines should be run WITH A SINGLE SAMPLE AT A TIME. Otherwise resource allocation and Nextflow errors could cause the pipeline to fail.

1. The recommended way of running the pipeline is to directly use the source code located here: /hot/software/pipeline/pipeline-call-sSV/Nextflow/release/, rather than cloning a copy of the pipeline.

   • The source code should never be modified when running our pipelines

2. Create a config file for input, output, and parameters. An example for a config file can be found here. See Nextflow Config File Parameters for the detailed description of each variable in the config file.

   • Do not directly modify the source template.config, but rather you should copy it from the pipeline release folder to your project-specific folder and modify it there

3. Create the input YAML using the template.See Input YAML for detailed description of each column.

   • Again, do not directly modify the source template input YAML file. Instead, copy it from the pipeline release folder to your project-specific folder and modify it there.

4. The pipeline can be executed locally using the command below:

• YAML input

nextflow run path/to/main.nf -config path/to/sample-specific.config -params-file path/to/input.yaml

• For example, path/to/main.nf could be: /hot/software/pipeline/pipeline-call-sSV/Nextflow/release/6.0.0-rc.1/main.nf
• path/to/sample-specific.config is the path to where you saved your project-specific copy of template.config
• path/to/input.yaml is the path to where you saved your sample-specific copy of input-sSV.yaml

To submit to UCLAHS-CDS's Azure cloud, use the submission script here with the command below:

python path/to/submit_nextflow_pipeline.py \
    --nextflow_script path/to/main.nf \
    --nextflow_config path/to/sample-specific.config \
    --nextflow_yaml path/to/input.yaml \
    --pipeline_run_name <sample_name> \
    --partition_type F16 \
    --email <your UCLA email, [email protected]>

In the above command, the partition type can be changed based on the size of the dataset. At this point, node F16 is generally recommended for larger datasets like A-full and node F2 for smaller datasets like A-mini.

* Manta SV calling wouldn't work on an F2 node due to incompatible resources. In order to test the pipeline for tasks not relevant to Manta, please set algorithm = ['delly'] in the sample specific config file.

Note: Because this pipeline uses an image stored in the GitHub Container Registry, you must follow the steps listed in the Docker Introduction on Confluence to set up a PAT for your GitHub account and log into the registry on the cluster before running this pipeline.

Flow Diagram:

Pipeline Steps:

Call Somatic Structural Variants - DELLY workflow:

1. Calling Single Sample Somatic Structural Variants

delly call --genome hg38.fa --exclude hg38.excl --map-qual 20 --min-clique-size 5 --mad-cutoff 15 --outfile t1.bcf tumor1.bam normal1.bam

This step requires an aligned and sorted tumor sample BAM file and a matched normal sample as an input for variant calling with DELLY. The stringent filters (--map-qual 20 --min-clique-size 5 --mad-cutoff 15) are added, which can drastically reduce the runtime, especially when the input BAMs are big. In the pipeline, these filters are specified in the NextFlow input parameters config file. If need be, these stringent filters can be adjusted in the config file.

2. Query the generated bcfs to get the sample names, which will be used in step 3.

echo -e "tumor\ncontrol" > samples_type
bcftools query -l t1.bcf > samples_name
paste samples_name samples_type > samples.tsv

3. Somatic Filtering

delly filter -f somatic -o t1.pre.bcf -s samples.tsv t1.bcf

This step applies somatic filtering against the .bcf file generated in Step 1.

Note: cohort based false positive filtering is compuationally heavy and not implemented in this pipeline.

Call Somatic Structural Variants - Manta workflow:

1. Calling Single Sample Somatic Structural Variants

configManta.py --normalBam "${normal_bam}" --tumorBam "${tumor_bam}" --referenceFasta "${reference_fasta}" --runDir MantaWorkflow
MantaWorkflow/runWorkflow.py

This step requires an aligned and sorted tumor sample BAM file and a matched normal sample as an input for variant calling with Manta.

Inputs

Input YAML

Field	Type	Description
sample_id	string	Tumor ID
normal	path	Set to absolute path to normal BAM
tumor	path	Set to absolute path to tumour BAM

---
sample_id: "sample_id"
input:
  BAM:
    normal:
      - "/path/to/BAM"
    tumor:
      - "/path/to/BAM"

Nextflow Config File Parameters

Field	Required	Type	Description
dataset_id	yes	string	Boutros Lab dataset id
blcds_registered_dataset	yes	boolean	Affirms if dataset should be registered in the Boutros Lab Data registry. Default value is false.
algorithm	yes	list	List containing a combination of SV callers delly, manta. List can contain a single caller of choice.
reference_fasta	yes	path	Absolute path to the reference genome FASTA file. The reference genome is used by Delly for structural variant calling. GRCh37 - /hot/resource/reference-genome/GRCh37-EBI-hs37d5/hs37d5.fa, GRCh38 - /hot/resource/reference-genome/GRCh38-BI-20160721/Homo_sapiens_assembly38.fasta
exclusion_file	yes	path	Absolute path to the Delly reference genome exclusion file utilized to remove suggested regions for structural variant calling. GRCh37 - /hot/resource/tool-specific-input/Delly/GRCh37-EBI-hs37d/human.hs37d5.excl.tsv, GRCh38 - /hot/resource/tool-specific-input/Delly/hg38/human.hg38.excl.tsv
map_qual	yes	integer	Minimum paired-end (PE) mapping quality (MAPQ) for Delly. Default set to 20.
min_clique_size	yes	integer	Minimum number of supporting PE or split-read (SR) alignments required for a clique to be identified as a structural variant by Delly. Adjust this parameter to control the sensitivity and specificity of Delly variant calling. Default set to 5.
mad_cutoff	yes	integer	Insert size cutoff, median+s*MAD (deletions only) for Delly. Default set to 15.
save_intermediate_files	yes	boolean	Optional parameter to indicate whether intermediate files will be saved. Default value is false.
output_dir	yes	path	Absolute path to the directory where the output files to be saved.
work_dir	no	path	Path of working directory for Nextflow. When included in the sample config file, Nextflow intermediate files and logs will be saved to this directory. With ucla_cds, the default is /scratch and should only be changed for testing/development. Changing this directory to /hot or /tmp can lead to high server latency and potential disk space limitations, respectively.
verbose	yes	boolean	If set to true, the values of input channels will be printed, can be used for debugging
docker_container_registry	optional	string	Registry containing tool Docker images. Default: ghcr.io/uclahs-cds

An example of the NextFlow Input Parameters Config file can be found here.

Outputs

Output	Description
.bcf	Binary VCF output format from DELLY with somatic structural variants if found.
.bcf.csi	CSI-format index for BCF files from DELLY.
.vcf.gz	zipped VCF output format from Manta with somatic structural variants if found.
.vcf.gz.tbi	TBI-format index for zipped VCF files from Manta.
report.html, timeline.html and trace.txt	A Nextflow report, timeline and trace files.
*.log.command.*	Process and sample specific logging files created by nextflow.
*.sha512	Generates SHA-512 hash to validate file integrity.

Testing and Validation

Test Data Set

Data Set	Run Configuration	YAML input	Output Dir	Normal Sample	Tumor Sample
A-mini TWGSAMIN000001-T003-S03-F	/hot/software/pipeline/pipeline-call-sSV/Nextflow/development/unreleased/mmootor-replace-input-csv-with-yaml/TWGSAMIN000001-T003-S03-F.config	/hot/software/pipeline/pipeline-call-sSV/Nextflow/development/input/yaml/call-sSV-input-TWGSAMIN000001-T003-S03-F.yaml	/hot/software/pipeline/pipeline-call-sSV/Nextflow/development/unreleased/mmootor-replace-input-csv-with-yaml/TWGSAMIN000001-T003-S03-F/	/hot/software/pipeline/pipeline-call-sSV/Nextflow/development/input/data/TWGSAMIN000001-N003-S03-F.bam	/hot/software/pipeline/pipeline-call-sSV/Nextflow/development/input/data/TWGSAMIN000001-T003-S03-F.bam
ILHNLNEV000009	/hot/software/pipeline/pipeline-call-sSV/Nextflow/development/unreleased/mmootor-replace-input-csv-with-yaml/ILHNLNEV000009-T002-L01-F_F32.config	/hot/software/pipeline/pipeline-call-sSV/Nextflow/development/unreleased/mmootor-replace-input-csv-with-yaml/ILHNLNEV000009-T002-L01-F_F32.yaml	/hot/software/pipeline/pipeline-call-sSV/Nextflow/development/unreleased/mmootor-replace-input-csv-with-yaml/ILHNLNEV000009-T002-L01-F/	/hot/project/disease/HeadNeckTumor/HNSC-000084-LNMEvolution/pipelines/call-gSNP/2020-12-22/ILHNLNEV000009-T002-L01-F//gSNP/2021-01-22_11.01.06/ILHNLNEV000009/SAMtools-1.10_Picard-2.23.3/recalibrated_reheadered_bam_and_bai/ILHNLNEV000009-N001-B01-F_realigned_recalibrated_reheadered.bam	/hot/project/disease/HeadNeckTumor/HNSC-000084-LNMEvolution/pipelines/call-gSNP/2020-12-22/ILHNLNEV000009-T002-L01-F//gSNP/2021-01-22_11.01.06/ILHNLNEV000009/SAMtools-1.10_Picard-2.23.3/recalibrated_reheadered_bam_and_bai/ILHNLNEV000009-T002-L01-F_realigned_recalibrated_reheadered.bam
DTB-266_WCDT	/hot/software/pipeline/pipeline-call-sSV/Nextflow/development/5.0.0/mmootor-release-5-0-0-rc-1/config/DTB-266_WCDT_F72.config	-	/hot/software/pipeline/pipeline-call-sSV/Nextflow/development/unreleased/mmootor-release-5-0-0-rc-1/DTB-266_WCDT/	/hot/data/unregistered/Quigley-Gebo-PRAD-SVMW/processed/output_call-gSNP/call-gSNP-DSL2-0.0.1/DTB-266/GATK-4.1.9.0/output/DTB-266_DNA_N_realigned_recalibrated_merged.bam	/hot/data/unregistered/Quigley-Gebo-PRAD-SVMW/processed/output_call-gSNP/call-gSNP-DSL2-0.0.1/DTB-266/GATK-4.1.9.0/output/DTB-266_DNA_T_realigned_recalibrated_merged.bam

Performance Validation

Testing was performed primarily in the Boutros Lab SLURM Development cluster. Metrics below will be updated where relevant with additional testing and tuning outputs.

Test Case	Test Date	Node Type	Duration	CPU Hours	Peak RSS (RAM)
TWGSAMIN000001-T003-S03-F	2023-01-19	F16	41m 35s	0.7	1.8 GB
ILHNLNEV000009-T002-L01-F	2023-01-20	F32	1d 23h 10m 46s	63.3	12.1 GB
DTB-266_WCDT	2023-01-19	F72	22h 55m 17s	45.1	13.2 GB
ILHNLNEV000005-T002-L01-F (with stringent filters. See #10 2f72de1)	2021-10-02	F72	1d 10h 55m 13s	2'478.4h	11.590 GB

References

• DELLY Structural Variant Caller
• Manta Structural Variant Caller

License

Authors: Yu Pan ([email protected]), Ghouse Mohammed ([email protected]), Mohammed Faizal Eeman Mootor ([email protected])

call-sSV is licensed under the GNU General Public License version 2. See the file LICENSE for the terms of the GNU GPL license.

call-sSV takes BAM files and utilizes DELLY and Manta to call somatic structural variants.

Copyright (C) 2021-2024 University of California Los Angeles ("Boutros Lab") All rights reserved.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.