I am analyzing PacBio IsoSeq data and I am using StringTie to assemble transcripts. I noticed the difference in the output files when I add a reference genome annotation (-G option in StringTie). In general I have less transcripts assembled when I give as imput reference genome annotation and I was wondering why. I know that the annotation of the genome is not the best (Borelian orangutang) and I would rather trust the data rather than the annotation provided.
I am attaching an example for one of the genes (IGV): the first track is reference annotation; the second is StringTie output when no reference annotation is provided; the third is StringTie output when reference annotation is provided (in the third case two novel assembled isoforms are missing)