fastqc kmer content error

[btaboada]

Hello,

I have 4 different samples and in all of them I got some weird peaks along the sequences in FastQC kmer content graphics (plz see the attached graphs). I would appreciate it very much if anyone has a clue of what is happened in my data set. Many thanks!

[MeganS]

What type of samples are these(whole genome, transcriptome, RAD, etc.)? It could be contamination of some sort. You can tile the kmers together to get a longer sequence (TATCCTCCAGTG). I would compare that sequence to your adapters, primers, and other possible sources of contamination. I would also check and see how many reads this is actually affecting.