Question: Finding mutations from bam files
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gravatar for banerjeeshayantan
24 months ago by
banerjeeshayantan140 wrote:

I have two bam files(~17GB) for both tumor and normal sample in case of pancreatic cancer. Now I want to find the mutations in the tumor sample. How do I do that? Should I check the variants for tumor vs normal sample, or tumor vs reference genome(hg19). Pleas excuse my ignorance as I am relatively new to the field and still has got a lot to catch up. Thanks

sequencing next-gen • 1.0k views
ADD COMMENTlink modified 24 months ago by MAPK1.4k • written 24 months ago by banerjeeshayantan140
0
gravatar for WouterDeCoster
24 months ago by
Belgium
WouterDeCoster41k wrote:

Have a look at the GATK best practices for somatic mutations as a (good) starting point

ADD COMMENTlink written 24 months ago by WouterDeCoster41k

Thanks for the link. Can you suggest some command line tools?

ADD REPLYlink written 24 months ago by banerjeeshayantan140
1

First read the pages, then ask again. The tools from the best practices are command line tools.

ADD REPLYlink written 24 months ago by WouterDeCoster41k
0
gravatar for MAPK
24 months ago by
MAPK1.4k
United States
MAPK1.4k wrote:

Yes, the first thing you would want to do is create a VCF file using GATK tools as WouterDeCoster has mentioned. You can then use different analyses to call for variants that are statistically significant from your normal sample (so you will be comaparing tumour vs normal samples). If you have many unrelated normal samples to compare with, you could also adopt statistical approaches to find mutations in your samples. Reading this paper could give you some insight: http://www.nejm.org/doi/full/10.1056/NEJMoa1301689#t=article

ADD COMMENTlink modified 24 months ago • written 24 months ago by MAPK1.4k
  1. SO first I am comparing reference vs tumor and creating the vcf file? and then tumor vs normal to call variants?
  2. Just to clarify, when you say, "if you have many unrelated normal samples to compare with", what do you mean? I have only two bam files normal and tumor taken from a single patient. By sample do you mean different patients? Or different sites of the body?
ADD REPLYlink written 24 months ago by banerjeeshayantan140

If you already have bam files, then use GATK protocol to create VCF file. Then do tumour vs normal comparison.

2. Just to clarify, when you say, "if you have many unrelated normal samples to compare with", what do you mean? I have only two bam files normal and tumor taken from a single patient. By sample do you mean different patients? Or different sites of the body?

You don't have an option to work with other statistical tests such as burden and SKAT test since you only have two samples.

ADD REPLYlink modified 24 months ago • written 24 months ago by MAPK1.4k

Thanks a lot for clearing that out. Really appreciate it.

ADD REPLYlink written 24 months ago by banerjeeshayantan140

If an answer was helpful you should upvote it, if the answer resolved your question you should mark it as accepted. Upvote|Bookmark|Accept

ADD REPLYlink written 24 months ago by WouterDeCoster41k
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