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Kmer sequences in 5' RNAseq reads

Should I to trim the first bases of RNAseq reads that contain 7_k-mer?

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k-mer rna-seq

First why do you want to trim first 7_k-mers ? Do u think they have very poor quality or they are adapter contaminations ? What your pipeline ? Expression or Assembly or something else ?

I don't know how to put images here to exemplify my question. :(

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1 answer

No, at least, not blindly. Even though FastQC will tell you the "per base sequence content" is problematic, and in general one can easily spot the first 5-10 bases as being non-randomly distributed, this does not necessarily means they are wrong. If you are really worried, you could map (or assemble and map, if you do not have a reference at hand) and check the alignment, if these bases do not align correctly, then you can trim.

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