Thank you, Alex.
My consultant did explain that PCR laboratory findings do vary from day-to-day and that the variation in my result from the last to the present is statistically insignificant. Therefore, I appear to be stuck around about MMR with zero mutations on the next-generation sequencing investigation. My consultant assures me that this is quite satisfactory and I need not be concerned.
Indeed, it is disconcerting when posters (who are super-responders) are alarmed that their PCR has increased from 0.0001% to 0.0002%. You are quite correct that we should not be comparing our personal result with others.
I have been told that the next generation sequencing tests for mutations are giving results, for the main part, identical to the standard local laboratory tests.
Let us know how you get on.