Size of cancer/normal sequence data

Question

[Gene_MMP8]

I have one tumor/normal WGS data from a breast cancer patient and the tumor bam file is 11.2 GB in size, while the normal bam file is 27.6 GB in size. Isn't this uncommon, considering tumor files are usually larger than normal ones?

Answer 1

[Devon Ryan]

It's a bit unusual to sequence a normal sample 2.5x as deep as the cancer sample that you're more interested in, yes. It's quite possible that the normal sample was on a different run or machine, where there was more space (and thus more total reads).

[Gene_MMP8]

So is it advisable to compare normal vs tumor and find the variants for this sample?

[Devon Ryan]

Yes. The only alternative is throwing away the data...which is not a terribly good alternative.

[Gene_MMP8]

Thanks for your reply.