<p>Several issues:</p>
<ol>
<li><p>There is no non-coding RNA genome. There are non-coding genes but the genome fasta files from Ensembl are always the entire genome and this is what you should align against. Probably you downloaded a transcriptome fata file.</p>
</li>
<li><p>If you aligned against a transcriptome fasta file (like ncRNAs) then it makes no sense to use a GTF file since GTF files have genome coordinates but you mapped against a selection of a transcriptome fasta, hence you have (specific) transcriptome coordinates. GTF and these coordinates are not compatible.</p>
</li>
</ol>
<p>Solution: Align your data against the entire genome (hg38), then use the GTF to get counts for all annotated genes, then do subsetting to specific genes if that is what you need.</p>

CC BY-SA 4.0
2023-12-01T03:03:50.387Z
Thank you so much. I guess i have been using transcriptome fasta file. will change that .
subhiksha sundaram
CC BY-SA 4.0
2023-11-29T16:02:24.407Z
2023-11-29T16:02:24.407Z
ATpoint
<p>I am working on RNA seq analysis and I would like to know the following things:</p>
<p><strong>Current Methods:</strong></p>
<ul>
<li>downloaded genome fasta file for non-coding rna from ensembl and got the gtf file for hg38</li>
<li>performed hist2 and got 17% alignment for my sample against ncrna genome</li>
<li>sorted the file and then ran feature counts with the hg38 gtf file but got zero counts</li>
</ul>
<p><strong>Question:</strong></p>
<ul>
<li>what could be the issue that is causing zero counts?</li>
</ul>
<p>My bam file after sorting has the SRR ID at first whereas the GTF file has chromosome no: . Could this be the issue?</p>

CC BY-SA 4.0
2023-11-25T07:37:32.973Z
Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
Community
CC BY-SA 4.0
2023-11-28T14:53:01.873Z
Did you spot-check where the alignments are?
Devon Ryan
CC BY-SA 4.0
2023-12-01T03:04:25.890Z
nope. i guess there was an issues with the refernce genomecompatibility.
subhiksha sundaram
<rna-seq><ngs><rna>
issue with rna seq analysis
# issue with rna seq analysis

(Asked by: username_0 on 2023-11-25)

I am working on RNA seq analysis and I would like to know the following things:

**Current Methods:**

* downloaded genome fasta file for non-coding rna from ensembl and got the gtf file for hg38
* performed hist2 and got 17% alignment for my sample against ncrna genome
* sorted the file and then ran feature counts with the hg38 gtf file but got zero counts

**Question:**

* what could be the issue that is causing zero counts?

My bam file after sorting has the SRR ID at first whereas the GTF file has chromosome no: . Could this be the issue?

**Tags:** rna-seq, ngs, rna
> **Comments:**
> **username_1**: Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.  
> **username_2**: Did you spot-check where the alignments are?  
> **username_0**: nope. i guess there was an issues with the refernce genomecompatibility.  

---

## 1 answers

### Answer by username_3 on 2023-11-29. Score: 3

Several issues:

1. There is no non-coding RNA genome. There are non-coding genes but the genome fasta files from Ensembl are always the entire genome and this is what you should align against. Probably you downloaded a transcriptome fata file.
2. If you aligned against a transcriptome fasta file (like ncRNAs) then it makes no sense to use a GTF file since GTF files have genome coordinates but you mapped against a selection of a transcriptome fasta, hence you have (specific) transcriptome coordinates. GTF and these coordinates are not compatible.

Solution: Align your data against the entire genome (hg38), then use the GTF to get counts for all annotated genes, then do subsetting to specific genes if that is what you need.

> **Comments:**
> **username_0**: Thank you so much. I guess i have been using transcriptome fasta file. will change that .  

---

