Using NGS.

Do you mean you will find tumor-derived DNA in the patient blood and detect new somatic mutations in it? For that, you need to know some characteristic sequence of the brain tumor. It's not in germline DNA seq, but in tumor DNA seq.

If you will find the seq in blood-derived DNA reads, maybe the read came from the tumor. Finding a new mutation is the next step.

However, the new mutation should be in the same read of the characteristic seq, so.....this may be a difficult story.

A higher concentration of cell-free DNA is evident in serum/plasma of Brain tumor patients. CtDNA to cfDNA ratio might be lowered due to the blood-brain barrier and cfDNA clearance mechanism, but there is the possibility of detecting the same mutation similar to primary tumor tissue. In post-op cases, the mutation could be detected only in the situation of recurrence and minimal residual disease (MRD). Another issue is the coverage and sensitivity of applied methods.

Thanks

By deep coverage NGS it is possible to find a primary mutations in the higer value, theorically, they must be more than the subsequently mutations, according to the time of occurence, comparison of the ct DNA vs cf DNA. is important too. The most newer mutations must not be detected, because of the cell degradation time and the number of the degraded new tumor cells, therefore, investigating on primary driver mutatons in serum is rational.

Dr. Mahammad Abbas Tafida, circulating methylome sounds very interesting.

@Taijun Hana.i am talking about detection of novel/ known somatic mutations using NGS in post operative cases. I am agree with @Adil Husain, mutations may be detected in mentioned scenarios. Also the mutations present in ctdna can be compared with primary tumor biopsy. To filter out germline mutations Lymphocytes DNA obtained from the same patient should be used.