Question: Problem bam files 0 counts
0
gravatar for Pin.Bioinf
11 days ago by
Pin.Bioinf20
Malaga
Pin.Bioinf20 wrote:

Hello, I am trying to get the counts of my experiment from the .bam files by using summarized experiment function in R.

My reads are single ends, not strand specific. Here is some R code:

gtffile <- file.path(dir2,"Homo_sapiens.GRCh38.91.gtf")
(txdb <- makeTxDbFromGFF(gtffile, format="gtf"))
(genes <- exonsBy(txdb, by="gene"))
library("GenomicAlignments")
se <- summarizeOverlaps(features=genes, reads=bamfiles,
                        mode="Union",
                        singleEnd=FALSE,
                        ignore.strand=FALSE,
                        fragments=FALSE )

I am getting 0 counts as the output for every sample and every gene. Anyone knows if it could be the .gtf file or if my .bam files are not correct? Ive done it many times. Any alternatives?

counts rna-seq mapping • 104 views
ADD COMMENTlink modified 10 days ago • written 11 days ago by Pin.Bioinf20
1

Please use the formatting bar (especially the code option) to present your post better. I've done it for you this time. Formatting bar

ADD REPLYlink written 11 days ago by Ram13k

Didn't you get any error? What is the output of samtools idxstats file.bam ?

ADD REPLYlink written 11 days ago by venu4.8k

I get :

samtools idxstats: fail to load index for "24_control.bam"
ADD REPLYlink modified 11 days ago by Ram13k • written 11 days ago by Pin.Bioinf20

Please use the formatting bar!

ADD REPLYlink written 11 days ago by Ram13k

Then you should index 24_control.bam by doing samtools index 24_control.bam.

Top thing to check when zero counts manifest is to ensure that chromosome names match in your alignments and annotation (i.e. chr1 =\= 1).

ADD REPLYlink modified 10 days ago • written 10 days ago by GenoMax42k

Thank you a lot, i was helping another person who had stumbled upon this problem, and i realized she was using different genome anotations for mapping and for quantification.

ADD REPLYlink written 10 days ago by Pin.Bioinf20
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