One of the major challenges of the 100,000 Genomes Project has been collecting tissue samples from participants so that DNA can be extracted and sequenced.
Early experiments showed that how the samples are collected, stored and processed can affect the quality of the DNA, and therefore the success of whole genome sequencing, so a new objective emerged: to transform pathology services’ tissue handling practices in the NHS.
How could we better preserve and process tissue samples to make sure DNA remained as intact as possible, giving the highest quality genome sequencing further down the “pipeline”? We know that fresh tissue produces excellent Whole Genome Sequencing results. But, some pathologists hesitate to use refrigeration for fresh tissue sampling in case it affects other diagnostic tests.
However, as set out in this paper by our pathology experts, Professor Louise Jones and Dr Clare Craig, these same changes are seen in samples that are treated in the conventional way, i.e. placed unopened into formalin until they can be batched for sampling.
This is why diagnostic biopsies are used, where possible, in preference to surgical resection samples when immunohistochemistry or other testing that may have a clinical impact is necessary. Dr Craig said:
Thought should be given into the quality of the conventional approach before critiquing the quality of any new approach. Pathologists have a challenge ahead to navigate how best to handle tissues to enable optimal results with respect to morphology, immunohistochemistry and molecular pathology.
In addition to the article, we have sets of videos (available both here on the website and via Vimeo) covering:
These videos have been accredited by the Royal College for Continuing Professional Development (CPD) credits; follow the links to request certificates.
We are also working on a short animation to describe how formalin damages DNA in tissue samples – watch this space for updates.