Hi All,
I am currently trying to find number of reads (sequenced from DNAseq) that are mapped to human genes. So I tried three different methods to validate whether I am getting the same read count. 1) samtools 2) featurecount 3) htseq-count
For example, considering this gene "WASH7p". As per the human GTF downloaded from UCSC for hg19, I have following exons in them.

Method1: using samtools command

Total read count as per samtools: 6
2) featurecount:

3) htseq-count
htseq-count -f bam -s no -i gene_id Sample_001_TGACCA_L001.bam Homo_sapiens/UCSC/hg19/Annotation/Genes/genes.gtf > Sample_001_Read_count_based_on_gene.txt 2>Sample_001_htseq_count.log &
WASH7P 0
Why htseq-count is giving "0"? Am I missing some parameters?
1 answer
If you lower the value of -a in htseq-count it'll probably produce identical results to featureCounts (though it'll take longer to run).
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Hi, Can you post the last lines of the Htseq output? There you'll find the number of reads which are ambiguous or land in un-annotated regions. Also the multi-mappings are listed there. If your reads map more than once, Htseq will not assign these to the genes.
Dear Michael,
Please find the requested information.
__no_feature 1234324
__ambiguous 123995
__too_low_aQual 347284
__not_aligned 2851
__alignment_not_unique 0