Large Scale Resequencing: Approaches and Challenges
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This document discusses the challenges of large scale DNA resequencing projects at the Wellcome Trust Sanger Institute. It describes their work on several major projects that have generated over 100 terabases of sequencing data, including the 1000 Genomes Project and UK10K. It outlines their data processing pipeline and strategies for managing the large amount of data through tiered storage and automated compute workflows. Finally, it notes that new high throughput sequencers like the Illumina HiSeq 2500 will allow generating a human genome in a single day, further increasing the scale of data production.
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Large Scale Resequencing: Approaches and Challenges
- 1. Large Scale Resequencing: Approaches and Challenges Thomas Keane Vertebrate Resequencing Informatics group Wellcome Trust Sanger Institute Hinxton, Cambridge, UK thomas.keane@sanger.ac.uk AGBT Tutorial Workshop 15th February, 2012
- 2. Sanger total sequence (2007-2009) Gbp AGBT Tutorial Workshop 15th February, 2012
- 3. Sanger total sequence to-date Gbp AGBT Tutorial Workshop 15th February, 2012
- 4. Vertebrate Resequencing Informatics Group Established in 2008 with Jim Stalker PIs: Richard Durbin and David Adams Initial projects 1000 Genomes project (http://www.1000genomes.org) Data processing, releases, aligner evaluation, sequencing Pilot 2008-2009: ~5Tbp (Nature 2011;467) Phase 1 2009-2011: ~30Tbp Phase 2 2011-: ~36.9Tbp (LowCov ilmn only) Mouse Genomes Project (http://www.sanger.ac.uk/ mousegenomes) Sequencing 17 laboratory mouse strains SNPs, indels, SVs, de novo assembly Approx. ~1.2Tbp (Nature 2011;477) AGBT Tutorial Workshop 15th February, 2012
- 5. UK10K Investigating the role of rare genetic variants in health and disease Whole genome cohorts: 4,000 individuals across two well-established and deeply phenotyped UK cohorts with ongoing longitudinal phenotype collection: TWINSUK – 2,000 ALSPAC – 2,000 6x (18Gbp) per sample Exomes: 6,000 exomes from 3 sets of extreme phenotype individuals Neurodevelopmental diseases – 3,000 e.g. schizophrenia, autism spectrum disorders Obesity – 2,000 e.g. severe childhood onset obesity Rare diseases – 1,000 e.g. severe insulin resistance, congenital heart disease, ciliopathies 5Gbp per sample Expect to generate ~100Tbp by end 2012 ~40Tbp from BGI AGBT Tutorial Workshop 15th February, 2012
- 6. Current Status Recently passed 1000 genomes in terms of total Gbp AGBT Tutorial Workshop 15th February, 2012
- 7. What are the challenges? Storage Software/Workflows NGS Compute Power AGBT Tutorial Workshop 15th February, 2012
- 8. Data Production Workflow Sample NA34842 NA87465 Sample/Platform merge Merge Up BAM BAM BAM Library merge Library Freeze BAM BAM BAM BAM …… BAM BAM Improvement BAM …… Alignment BAM BAM BAM BAM Import (bwa, smalt etc) Fastq Fastq Fastq …… Fastq Fastq + Improvement AGBT Tutorial Workshop 15th February, 2012
- 9. Data Production Workflow Chr1 Chr2 Chr3 NA19294 … NA18943 … Merge NA19305 . . . . . . . . . . . across NA19309 … RG:NA19294 RG:NA18943 RG:NA19305 Cross-sample BAMs SNPs/indels SVMerge samtools GATK Genome STRiP VQSR Variant BEAGLE/ Impute2 Calling VEP Annotation Final VCF AGBT Tutorial Workshop 15th February, 2012
- 10. Storage Challenges Expect ~200Tbp of sequence in 2011-2012 Working estimate including processing, release, and variant calling 10bytes per bp Storage considerations Scalability – can we easily add more storage units? Backup and disaster recovery – what do we really need to keep? Performance – sufficient I/O throughput to serve compute nodes Cost Data Formats Standardised formats – BAM & VCF Minimise the number of copies Aim for two copies at most – original lanes + release (stripped) BAM AGBT Tutorial Workshop 15th February, 2012
- 11. A Tiered Storage Solution Cost Size 2 1 3Gb/sec CPU Farm 1 3 800Mb/sec Off- Off- 2 2 site site Level 1 Data: Current release vertical BAMs Processes: BAM merging + splitting, Variant calling (SNPs, indels, SVs) Level 2 Data: Lane level BAMs Processes: Alignment, recalibration, local realignment Level 3 Data: Previous release BAMs + variant calls backup AGBT Tutorial Workshop 15th February, 2012
- 12. Data release + archiving: iRODs Rule-Oriented Data management systems iRODs Open source – origins in particle physics world Most important feature of iRODS is the Rule Engine nfs02 nfs20 Akin to source control system Customise own application level metadata nfs03 nfs01 Off- e.g. run, lane, plex, sample, library…. site Stores/searches key-value metadata on files: List all files from UK10K studies: imeta -z seq qu -d study like 'UK10K_%’! /seq/5363/5363_1.bam! /seq/5363/5363_2.bam (.....and a whole lot more)! Get metadata about a file: imeta ls -d /seq/6534/6534_3#7.bam sample! attribute: sample! value: QTL191953! Sanger production: BAM files from runs per lane per plex deposited BMC Bioinformatics 2011, 12:361 Recently adopted for UK10K internal data release and archiving Users use meta-data queries to find their data Files can be part of multiple releases http://www.irods.org AGBT Tutorial Workshop 15th February, 2012
- 13. Compute Pipeline Management: VRPipe VRPipe Managed and automated execution of sequences of arbitrary software against massive datasets across large compute clusters Error handling, optimal memory requests, batching of jobs, retrying failures, failure reporting, highly extendable, detailed job statistics 1000 Genomes Phase 2 processed through VRPipe Tracked ~1 million jobs Total serial wall time: 9886 days, 3 hrs, 43 mins, 25 secs bwa_aln_fastq: ~2443 days total serial wall time Mean memory: 941MB/job (max 5637) 2012 sb10@sanger.ac.uk Fully migrate all NGS processes to VRPipe (data processing, SNP/ indel/SV variant calling, and RNA-seq/ChIP-Seq pipelines) Management front-ends Create distributable VM for cloud rollout http://www.github.com/VertebrateResequencing/vr-pipe/wiki AGBT Tutorial Workshop 15th February, 2012
- 14. Even more scale up in 2012 – HiSeq 2500 Currently takes 1-2 weeks to sequence a human genome High depth human genomes in a single day – Illumina HiSeq 2500 Caucasian family with a severe T-cell deficiency in affected sibling Single run on HiSeq 2500 by Illumina per individual PF % ≥Q30 Mismatch Mismatch Run time Sample Yield % Align (Gbp) value R1 (%) R2 (%) (hrs) Father 117.7 89 92.6 0.4 0.5 25.5 Mother 125.7 90.2 92.8 0.4 0.5 25.5 Affected 124.4 90.3 92.4 0.4 0.5 25.5 AGBT Tutorial Workshop 15th February, 2012
- 15. What does the data look like? AGBT Tutorial Workshop 15th February, 2012
- 16. Upcoming Changes in 2012 We cannot keep all of the data 2007-2008: Keep everything including images from runs 2009: BAM/Fastq – all of the base quality information 2010-2011: Stripping original qualities and other unused tags 2012-: Current formats contain lots of repetition Reference based compression Reducing quality information e.g. quality binning or quality budgets Potential formats: CRAM and/or Reduced BAM AGBT Tutorial Workshop 15th February, 2012
- 17. CRAM Format TGAGCTCTAAGTACC! 329183050298757! CRAM models for compression TGAGCTCTAAGTACC! TGAGCTCTAAGTACC! 002020010022212! -2---30---9---7! Horizontal Vertical Do nothing Lossless Quality lossy 100 10 1 0.1 CRAM current Untreated CRAM CRAM CRAM substitutions/insertions performance lossless combination model model CRAM v0.6 released 13.2.12: • Option to preserve all unmapped reads • Pairing information preservation regardless of distance • Performance and bug fixes • Revised and improved lossless mode • Arbitrary tags http://www.ebi.ac.uk/ena/about/cram_toolkit Source: Ewan Birney/Guy Cochrane, EBI AGBT Tutorial Workshop 15th February, 2012
- 18. Any questions? Richard Durbin URLs • VRPipe: https://github.com/VertebrateResequencing/vr-pipe David Adams • iRODS@Sanger: BMC Bioinformatics 2011, 12:361 • http://www.slideshare.net/thomaskeane AGBT Tutorial Workshop 15th February, 2012