I've run macs2 callpeaks and in the .narrowPeak file I have many rows for chromosomes with names like "chrUn_KI270522v1". Can anyone tell me what this means? The peak was found in an unknown chromosome? Is this due to noise and can be ignored? I have a feeling if I ignore those rows I'm going to be missing out on important info but I get many errors when I try to annotate the peaks because those aren't real chromosomes.
Any insight would be appreciatd.
FYI - These are human cells.