what is different between TCGA samples and cases?

Question

[liuxiaomeng90]

I download GBM data from TCGA. It is showed that there are 508 cases in mRNA track. I download all of the TN data from UNC AgilentG4502A_07 track of level 3. I'm wondering why there are 532 filenames in FIL_SAMPLE_MAP.txt. Is it mean that 1 case was sequenced several times?

Answer 1

[liuxiaomeng90]

I sent email to TCGA for help. And this is the specialist's answer:

I have received your question regarding the difference between cases and samples in TCGA. Each patient is considered a case. Each patient can have more than one sample analyzed in TCGA data. In the example you gave me, you will find samples of type 01 (primary solid tumor) and type 02 (recurrent solid tumor) that come from the same patient (e.g., patient TCGA-06-0125). This can account for the difference in numbers.