My last 3 blood samples sent to HH from Exeter for PCR testing under WIN and Spirit 2 trials have come back stating either that the blood was too old once they came to test it, or, for the last two samples (June and September 2013), that the BCR-ABL transcript level is too low for accurate and reliable quantification so the PCR result is to be interpreted with caution.
Does anyone know why this happens and if there is anything I can do to provide a better transcript level?
Best wishes to one and all,
Chrissie
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Poor blood samples
Hi Chrissie
The same thing happened to me a number of times - basically the blood was being posted from my local hospital to Kings and due to the length of time it was taking they could not analyse it. I had a meeting with the department at my hospital (after I had calmed down!) and insisted that the bloods were sent by courier which they did. I now have the majority of my appointments at Kings so the situation no longer occurs but I would say you need to push to have your bloods sent in a different way.
Good luck
K
Hi Chrissie,
I think Karen makes a good point and you should try to ensure your blood sample is transported as quickly as possible. It is the RNA that is extracted from the cells in the sample and tested by PCR. After your blood sample is taken the cells it contains start to die and the RNA quickly degenerates. This is why time is of the essence if your sample is to be viable when it gets to the testing lab.
I am not sure if we can do anything to help provide a 'better' transcript level. A good question though and one I will ask Prof. Apperley at my next appt.
The following preview from our yet to be published booklet on q RT-PCR testing might help as it explains some the important factors that can affect any one sample. We hope to publish this booklet soon, just working on the final edit now.
Sandy
Factors that affect the suitability of a sample sent for q RT-PCR testing:
If a blood sample has been in transit for several days, or has been stored for too long after collection, the cells it contains will be in the process of dying and the mRNA will already have started to degrade. This means there is greater chance of an inaccurate result and many labs will not report results if the control cells in the in a sample are at too low a level.
The lowest acceptable level for a control gene in any one sample is 10,000 copies.
A good diagnostic sample will contain equal amounts of transcripts of both a control gene and the abnormal gene (BCR-ABL1).
The result will show a relative proportion (expressed as a percentage) of how many leukaemic (BCR-ABL1 positive) cells are present over the total number of cells analysed in the blood sample.
*However, a sample taken from a patient who is responding well to therapy is more likely to contain a good amount of ABL (a normal gene present in all cells) and a much lower amount of the BCR-ABL1 gene. This is because cells containing the abnormal gene would have been killed by the therapy and would be very few in number.