WES - how deep do you sequence your germline control

[onconaut]

Hello Seqers,

we currently do WES with a mean coverage of ~120x for tumor as well as the germline samples. Since we only use the germline to help us with the somatic alteration calls I was thinking about cutting the coverage of the germline samples in half to free up some real estate on the flowcell. Does any one have experience with this?

Thanks, O.

[Bukowski]

We'd normally do 50x on the normal and 100x+ on the tumour - I think that's quite a common strategy.

[bilyl]

It depends on your downstream processes. If you are simply calling SNVs then it doesn't really matter. But for other applications (eg. CNVs), many programs prefer to have similar coverage between your tumor and normal. Even if they don't require it, you are getting rid of other sources of variation (eg. by capturing the same amount of DNA in the same exome hyb reaction).