This is a test version of Biostars. For the public version, visit https://www.biostars.org.
BAM FLAG mate unmappedand mate reverse strand

Can anyone please explain in one sentence the meaning of these two flags (mate unmapped and mate reverse strand)? If I have paired-end sequencing data in samtools flagstat the values should be 0 because it is not mate pair sequencing? Thanks a lot for explanation.

bam
• 1,320 views • link
updated by i.sudbery i.sudbery • written by esimonova.me • esimonova.me

1 answer

In the BAM specification "mate" is not the same thing as "mate" in mate-pair sequencing. It, more or less, mean "pair".

The meanings are 

read1    mapped    +
read2    mapped    -

"mate unmapped" is unset and "mate revserse strand" is set.

read1    mapped    -
read2    unmapped    +

"mate umapped" is set and "mate reverse strand" is not set.

The specification has slowly been changing over to using the term "next read in template" rather than "mate", but the flags still use the old language.

• 0 views • link
written by i.sudbery i.sudbery

Log in to answer this question.

More posts like this