Abstract: A method of diagnosing an MSI cancer in a patient including extracting and sequencing DNA from a tumoral sample and if available from a normal sample and operate an analyse of MNRs. The method is based on the demonstration that the FDA-approved NGS-based diagnostic test for identifying MSI in mCRC and nmCRC gave inaccurate results when compared with the gold standard reference methods. Consequently, whole exome sequencing (WES) data from all samples was further analyzed to improve detection of the MSI genomic signal in CRC and other primary tumor types. This allowed identification of weaknesses and limits of MSISensor and the design and validation of a newly optimized algorithm, namely MSICare. The high accuracy of MSICare for the detection of MSI in CRC and non-CRC tumors should allow it to become a future reference test for assessing MSI in pan-cancer.

Abstract: The present invention relates to the diagnostic of CMMRD. In the present work, the inventors aimed to develop a test that could drastically simplify and improve the diagnosis of CMMRD based on DNA sequence analysis of primary blood cells (PBCs) from patients. Using massive parallel sequencing, they explored the possibility that MSI, the main genomic and functional consequence of constitutive MMR-deficiency, was likely to occur in CMMRD PBCs well before any transformation. Thus the present invention relates to a method of diagnosing a CMMRD cancer or a MSI leukemia/lymphoma in a patient in need thereof.