Mosaicism: VHL Gene in only Certain Areas?

hello,

Over the last month I have been having my yearly scans, the last was yesterday when I had my eyes checked and the chance to speak to my geneticist. He told me that my eyes were all clear, my abdomen scans were clear and that there were no changes to the tumours already present in my spine or head. He has not been able to find the gene in me and I have been tested a few times, the first when I was 13 and I am now 20. He took a new sample of blood from me to test. We discussed the fact that they had not found the gene and he said it could be that it wasn't present in the sample taken at the time, but then he went on to mention that as I had no growths in my eyes or abdomen that it may be possible that only the cells in my brain and spine have the faulty gene. He said this may be possible to find out by taking a sample from the tumours that have already been removed. I have given him permission to do this and so I will have to wait to hear any news.

I have never heard of this before. I know that because I havent had any growths in other parts of the body doesnt mean I never will, but how is it possible that the VHL gene has singled itself out to just those areas of the body where I do have growths?

Has anyone else ever heard of this or are going through a similar situation?

Looking forward to hearing from you.
Thank you
Linsey.