How to know if its Somatic or Germline?

[MrOfficerSir]

I’m analyzing genetic data and trying to determine whether a mutation is somatic or germline. I know germline mutations are inherited and present in all cells while somatic ones occur later and are often cancer related. If I don’t have matched normal tissue, is there a way to tell from the data alone? Can variant allele frequency, databases like gnomad or certain tools help differentiate them? Any tips or recommended approaches would be appreciated.

 

[Emali_day]

You can make an educated guess, but without matched normal, it's never 100% and germlines usually sit around 50% or 100%, somatics lower, but copy number can knock it all off, anyway don't assume rare = somatic with gnomad

 

[fastqfanatic0761]

To assess VAF levels, remember that if it's under 40%, it likely points to a somatic mutation, while a level close to 50% usually indicates a germline mutation. Oh, and make sure to cross-reference this information with population databases like gnomAD and COSMIC to identify any mutation classification trends.

 

[matrix|maker]

Yeah, VAF thresholds and checking databases really help nail down those mutation types.