Tag: MAPQ

Samtools flagstat confusing result of a merged bam file

Hi, I am a bioinformatics student and I am struggling with an issue, I had paired-end fastq files for one sample with some low-quality bases at the end and adapter contamination, so I went and I trimmed my reads with trimmomatic, it gave me 4 files that I used for…

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[SOLVED] changing the order of input changes samtools merge ouput

I realized that this is a stupid mistake I have made. Since samtools do not overwrite the files by default, the output that I get from samtools merge output.bam f2.bam f1.bam wan’t what I thought it was below is my original post ++++++++++++++++++++++++++ I’m using samtool/1.9.0 and I’m trying to…

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Overestimation of number of reads from nanopore data (flagstat)

Same issue as mentioned on the minimap2 tool: github.com/lh3/minimap2/issues/236#issue-361097444 For example nanopore reads aligned to the host transcriptome the flagstat output is: 5953480 + 0 in total (QC-passed reads + QC-failed reads) 2961480 + 0 secondary 22696 + 0 supplementary 0 + 0 duplicates 4195469 + 0 mapped (70.47% :…

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Samtools flagstat

Samtools flagstat 1 I aligned my ONT sequencing run with minimap2, subsequently I filtered the file using samtools view -b -F 256 aln_transcriptome_sorted_6.bam -o filtered_aln_transcriptome_6.bam to end up with primary alignments only. When I run samtools flagstat on the filtered file I get the following output: 3502608 + 0 in…

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Primer design for variants in duplicated genes?

The issues you face relate to the fact that the majority of the genome exhibits sequence similarity, i.e., similarity with other regions in the genome. Much of this is indeed related to gene duplication events, with the duplicated genes acquiring new functionality over time due to mutations. As a rough…

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Single-cell DNA and RNA sequencing reveals the dynamics of intra-tumor heterogeneity in a colorectal cancer model | BMC Biology

Organoid culture of small intestinal cells and lentiviral transduction C57BL/6J mice and BALB/cAnu/nu immune-deficient nude mice were purchased from CLEA Japan (Tokyo, Japan). The small intestine was harvested from wild-type male C57BL/6J mice at 3–5 weeks of age (Additional file 1: Figure S9A). Crypts were purified and dissociated into single cells,…

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MAPQ (Mapping quality) of 0 for most reads from BWA-MEM2 (with no secondary alignment or other apparent reason)

Hello, I got a very weird output from BWA-mem2 – most of the reads have mapping quality of 0, even though there is no secondary alignment or anything else suspicious. I got sequencing data that was aligned with Novoalign to hg18, the data was bam files. I needed to realign…

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Output of samtools view, what does the third column actually represent?

The samtools view outputs information from SAM and BAM files in SAM format. You can find a description of the SAM format here: samtools.github.io/hts-specs/SAMv1.pdf Section 1.4 deals with the meaning of each of the manditory coloumns. It includes the following table: Col Field Type Regexp/Range Brief description |—|——|——-|—————————-|—————————————-| 1 QNAME…

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qualimap2 mean mapping quality

qualimap2 mean mapping quality 0 I’ve done a contrast experiment to see the difference between the bam with BQSR and the bam without BQSR. I use qualimap to evaluate both bams. This is the confusing part. Using hap.py and the giab na12878 truth vcf, shows the bam with BQSR is…

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How To Filter Mapped Reads With Samtools

Hi, You get a bam (machine readable sam) file after mapping, and it contains information about mapped and unmapped reads. To get the unmapped reads from a bam file use: samtools view -f 4 file.bam > unmapped.sam the output will be in sam to get the output in bam, use:…

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Calling variants on reads with MAPQ=0 on HaplotypeCaller or bcftools mpileup

Calling variants on reads with MAPQ=0 on HaplotypeCaller or bcftools mpileup 2 I am working with about 500 samples of human exome data. used hg19 to align my reads and ran a standard best-practices GATK workflow. Later only to realise that a small 1Mb loci has not mapped properly due…

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Mapping quality and XS score

Mapping quality and XS score 0 Hi, I am currently looking through bam files using igv to manually check if the mutations not called by Mutect2 are really an error or not. Until now, to filter reads with low quality, I have used only MAPQ > 30 and didn’t consider…

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How to properly combine two bam files of a paired-end data

How to properly combine two bam files of a paired-end data 3 Hi all! I am mapping a paired-end read separately using bowtie2. After that, I want to combine the two bam file into one for downstream analysis. How to properly do this combination? I tried: samtools sort -n R1.bam…

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