Can you identify a cancer cell's host from its DNA?

Question

Criminals (especially murderers) are often convicted at least partially by matching their DNA to evidence left at the scene of the crime (hair, skin, blood, semen, etc). DNA labs are getting really good at matching smaller and smaller samples of cells with their host.Cancer cells are different. They are created when the DNA in them is altered through mutation and/or outside influence. As I understand it, the DNA in a cancer cell is different from all the other cells in your body.Does anyone know if it is different enough that it cannot be used to successfully identify which host a sample came from? If the only evidence left behind by a criminal was some cancer cells, could a DNA lab say it came from them?

ttyprintk · Accepted Answer

I&rsquo;m not a researcher. I think we discovered the easily-comparable variation used in forensics quite a long time ago before discovering (both healthy and pathogenic) mosaicism. I _think_ the former relies on optical comparison while the latter relies on a full sequence.So, a court would prefer the long legacy of statistics about polymorphism before more-complicated sequencing. But that leaves out your specific edge case. For example, some cancers alter regions of chromosomes or jettison the Y chromosome altogether.An interesting counterexample may be monozygotic twins. I imagine an optical comparison could confirm either or both twins match, but later-developed tests might rule one out. Those tests might be sequencing, or microbiome, etc. If the sample shows evidence of cancer, and only one twin has (some) cancer, I think we should not presume that the DNA evidence is strong enough to prove anything.