MAPQ values are really useful but their implementation is a mess

One of the standard fields in the SAM/BAM file format is the mapping quality (MAPQ) value. This value can be very useful to help filter mapped reads before doing downstream analysis – unfortunately the implementation of this value is in no way consistent between different aligners so it takes a fair bit of research to know how to use it appropriately. Mis-applying the filter could cause reads to be inappropriately excluded from an analysis.

March 17, 2016 All Technologies, All Applications, BamQC, SeqMonk

Mispriming in PBAT libraries causes methylation bias and poor mapping efficiencies

Random priming in PBAT libraries introduces drastic biases in the base composition and methylation levels especially at the 5′ end of all reads. As a result, affected bases should be removed from the libraries before the alignment step.

March 11, 2016 Illumina, Methylation, PBAT, BamQC, Bismark, FastQC, Trim Galore!