Question: htseq-count results in all reads with no feature - chromosome naming mismatch issue between genome and annotation
1
gravatar for sf533
8 months ago by
sf533 • 20
sf533 • 20 wrote:

Hi,

I am sorry that this similar question has been asked before but I have read through endless posts and can't find solution.

I have mapped my reads using Tophat and have 97% reads mapped. But when I then try to run htseq_count all my reads are coming up as no feature. Please see attached pictures.

(admin fix for links)

I am aware that this is probably a problem with the gtf file and bam file columns not matching but I have tried every gtf file for hg38 I can find and keep getting same issue. I also tried STAR instead of Tophat and got same issue.

Please provide advice as this is urgent.

Thank you,

Sarah

ADD COMMENT • link • modified 8 months ago by Jennifer Hillman Jackson ♦ 25k • written 8 months ago by sf533 • 20
0
gravatar for Jennifer Hillman Jackson
8 months ago by
United States
Jennifer Hillman Jackson ♦ 25k wrote:

Hi Sarah,

I can't see your graphics - these need to be hosted by some public site then linked into questions here. I use https://imgur.com/ but any public link will work.

That said, I agree the problem is likely with the GTF (one of the most common reasons for failures). If you mapped against the hg38 genome indexed at Galaxy Main https://usegalaxy.org -- or UCSC was your genome source when indexing on your own server, try using the UCSC version of the annotation from iGenomes: https://support.illumina.com/sequencing/sequencing_software/igenome.html. Download the tar archive, unpack it locally, then upload just the genes.gtf to Galaxy (use FTP).

Give that a try first. If the job still fails:

  • Double check you actually mapped against hg38 with Tophat ("rerun" or "job details" will have the original inputs recorded)
  • Make sure there are hits in the resulting BAM datasets
  • Try using HISAT2 instead since both Tophat and Tophat2 are considered deprecated
  • Review your steps versus those in this tutorial (uses FeatureCounts, but Htseq-count can be used instead): https://galaxyproject.org/tutorials/nt_rnaseq/

More resources:

If you cannot find the problem after doing the above, and you can reproduce this at Galaxy Main, a bug report can be sent in from one of the error datasets. Please leave the inputs/outputs undeleted and include the link to this Galaxy Biostars post in the comments. How-to: https://galaxyproject.org/issues/

Thanks! Jen, Galaxy team

ADD COMMENT • link modified 8 months ago • written 8 months ago by Jennifer Hillman Jackson ♦ 25k

Ok, I can see your graphics now. I am reviewing but it might not be enough - a bug report for this type of issue is usually better/faster.

ADD REPLY • link written 8 months ago by Jennifer Hillman Jackson ♦ 25k

Well, that was fast anyway! Ok, the chromosome identifiers in your GTF are not formatted in the same way as UCSC's hg38 are formatted. Try using the iGenomes GTF - it will be a match.

https://galaxyproject.org/support/chrom-identifiers/

ADD REPLY • link written 8 months ago by Jennifer Hillman Jackson ♦ 25k
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