DaehwanKimLab / hisat2

Graph-based alignment (Hierarchical Graph FM index)
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Different mapping results between HISAT and TopHat #252

Open ConcettaDe4 opened 4 years ago

ConcettaDe4 commented 4 years ago

Hi all!

I am performing a genome-guided transcriptome assembly with Stringtie.

Before the transcriptome assembly, I have mapped my paired-end reads of the same sample with HISAT2 and TopHat2 and for each mapping I performed the transcriptome assembly.

In my transcriptome assembly I noticed that in a region, Stingtie assembled only one transcript with HISAT mapped reads, while Stringtie assembled two transcripts with TopHat mapped reads. When I check this region, I noticed that HISAT mapped both mates of fragments and some mate are spliced-aligned supporting the reconstructed isofom. In the same region TopHat mapped only one mate of the fragment and the other mate is unmapped, so I did not have the spliced mate and I obtained two different isoforms instead of only one isoforms as HISAT.

I was wondering why HISAT is able to map both mates while TopHat did not map one mate of the fragment.

Thank you,

Concetta