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sam flag count

Dear all,

I have paired-end data of 150bp and i use bwa-mem to align it.

bwa-mem ref_genome R1.fq.gz  R2.fq.gz > aligned_reads.sam

After the alignment, i have check the flags proportions and there is something that i do not understand, i have different count for sam flags 99/147 or 83/163.

99: 6239811
147: 6241593

 

83: 8113628
163: 8112417

This is the first time i have this, usually i get the same number of flags for 99/147 or 83/163.
Does it means that there is a problem during the alignment ?

Thank you for your help!

alignment

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2 answers

Decoding sam flags

[ Edited link (ATpoint) ]

Can you check and correct this link? It is not going anywhere at the moment.

the link is not working

Edited the link, please try again.

thank you for the link but the thing that i do not understand is if a have a count of for example 2000 reads for sam flag 99 i should get also the same number of reads for its mate 147?

the link is not working

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