Clinical background:
The MSI-Plus Assay was developed to provide a single tumour test for Lynch syndrome screening and oncological management of colorectal cancers. It uses multiplex PCR to amplify 14 highly sensitive mononucleotide repeats, the BRAF c.1799T>A locus, and mutation hotspots in KRAS and NRAS.
Amplicons are sequenced followed by automated analysis to call MSI status and BRAF/RAS variants, providing data to interpret immune checkpoint inhibitor (ICI) and anti-EGFR response as well as Lynch syndrome risk. MSI status confirmation is also available for upper tract gastrointestinal tumours to determine potential response to ICIs and inform on the likelihood of having Lynch syndrome, when appropriate.
Specimen container paediatric:
Not performed on paediatric samples
Specimen container adult:
FFPE curls for tissue biopsies
Minimum volume paediatric:
Not performed on paediatric samples
Minimum volume adult:
5 × 10 µM curls, ideally >10% tumour content
Special requirements:
Sample Stability:
N/A
Transport requirements:
Samples should be sent to laboratory immediately.
Freq Analysis:
Every other day
Add On Test:
Can be added to any genetics sample where appropriate material has been stored
Quality Assurance:
UK GenQA
Interpretation:
By (senior) genetic technologist
Reference Ranges:
N/A
Factors Affecting Result:
Quality and size of sample
Referenced Documents:
N/A
Other Info:
Ongoing research is exploring use of the MSI-Plus Assay in other tumour types, for constitutional MSI analysis, and for liquid biopsy testing