bio-workflows-longread-sv-pipeline

Version Compatibility

Reference examples tested with: bcftools 1.19+, minimap2 2.26+, samtools 1.19+

Before using code patterns, verify installed versions match. If versions differ:

• CLI: <tool> --version then <tool> --help to confirm flags

If code throws ImportError, AttributeError, or TypeError, introspect the installed package and adapt the example to match the actual API rather than retrying.

Long-Read SV Pipeline

"Detect structural variants from my long-read sequencing data" → Orchestrate minimap2 alignment, SV calling (Sniffles2/cuteSV), VCF merging across callers, annotation (AnnotSV), and visualization for ONT or PacBio data.

Complete workflow for detecting structural variants from ONT or PacBio long-read data.

Workflow Overview

Long reads (ONT/PacBio)
    |
    v
[1. QC] ----------------> NanoPlot
    |
    v
[2. Alignment] ---------> minimap2
    |
    v
[3. SV Calling] --------> Sniffles / cuteSV
    |
    v
[4. Filtering] ---------> bcftools
    |
    v
[5. Annotation] --------> AnnotSV (optional)
    |
    v
Filtered SV VCF

Primary Path: minimap2 + Sniffles

Step 1: Quality Control

# ONT reads QC
NanoPlot --fastq reads.fastq.gz \
    --outdir nanoplot_output \
    --threads 8

# Check key metrics
# - Read N50 should be >10kb
# - Mean quality >Q10
# - Total bases sufficient for coverage

Step 2: Alignment with minimap2

# ONT reads
minimap2 -ax map-ont \
    -t 16 \
    --MD \
    -Y \
    reference.fa \
    reads.fastq.gz | \
    samtools sort -@ 4 -o aligned.bam

samtools index aligned.bam

# PacBio HiFi
minimap2 -ax map-hifi \
    -t 16 \
    --MD \
    -Y \
    reference.fa \
    reads.fastq.gz | \
    samtools sort -@ 4 -o aligned.bam

# PacBio CLR
minimap2 -ax map-pb \
    -t 16 \
    --MD \
    -Y \
    reference.fa \
    reads.fastq.gz | \
    samtools sort -@ 4 -o aligned.bam

QC Checkpoint: Check alignment stats

samtools flagstat aligned.bam
samtools depth -a aligned.bam | awk '{sum+=$3} END {print "Average coverage:",sum/NR}'

• Mapping rate >90%
• Average coverage >10x for SV calling (>20x preferred)