Insert Sizes for Paired End Reads Exactly the same as Read Length

[rlowe]

Hi All,

We have performed BS-Seq experiment on some samples and when mapping notice a high spike in insert size that is exactly overlapping the read size. (100bp). Does anyone have any ideas where this could have come from? It looks like it may be similar to this problem

http://seqanswers.com/forums/showthread.php?t=16635

Again we do not see this peak on Bioanalyser. Attached is a plot of our results from mapping. On the x-axis is overlap of reads so the spike is at 0bp e.g. 100bp insert.

Thanks,
Rob