Does having an actual date for sequencing open the potential for subject identification?

[schristley]

My understanding is one technique to avoid subject identification is by replacing dates with relative times from an arbitrary t0 time point and that's what we have done from most of the AIRR standards. However I noticed sequencing_date is an actual date. Does it make sense to convert this to a relative time as well?

[scharch]

sequencing_date is when you turn on the NextSeq, right? That could be arbitrarily long after sampling or even after the conclusion of the study. So I'm not sure relative time would make sense...

[schristley]

Yeah, that's my understanding, though it should be before the conclusion of the study, if the study involves analyzing AIRR-seq then you need to sequence first... But yes, it could be arbitrary long after sampling or very soon.

I don't have a clear use case in my mind on what might happen. I was mainly wondering, if you knew the sequencing date then maybe there was the potential to backtrack and roughly determine other dates. As always you need other information if trying to do identification.

Thinking about it in another way. By having a date, you don't really know when the sequencing was done in comparison to the sampling, did the sample sit in the freezer for 20 years? Maybe that's a useful tidbit?