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Introduction: Lynch syndrome-associated cancer develops due to germline pathogenic variants in one of the mismatch repair (MMR) genes, MLH1, MSH2, MSH6 or PMS2. Somatic second hits in tumors cause MMR deficiency, testing for which is used to screen for Lynch syndrome in colorectal cancer and to guide selection for immunotherapy. Both MMR protein immunohistochemistry and microsatellite instability (MSI) analysis can be used. However, concordance between methods can vary for different tumor types. Therefore, we aimed to compare methods of MMR deficiency testing in Lynch syndrome-associated urothelial cancers. Methods: Ninety-seven urothelial (61 upper tract and 28 bladder) tumors diagnosed from 1980 to 2017 in carriers of Lynch syndrome-associated pathogenic MMR variants and their first-degree relatives (FDR) were analyzed by MMR protein immunohistochemistry, the MSI Analysis System v1.2 (Promega), and an amplicon sequencing-based MSI assay. Two sets of MSI markers were used in sequencing-based MSI analysis: a panel of 24 and 54 markers developed for colorectal cancer and blood MSI analysis, respectively. Results: Among the 97 urothelial tumors, 86 (88.7%) showed immunohistochemical MMR loss and 68 were successfully analyzed by the Promega MSI assay, of which 48 (70.6%) were MSI-high and 20 (29.4%) were MSI-low/microsatellite stable. Seventy-two samples had sufficient DNA for the sequencing-based MSI assay, of which 55 (76.4%) and 61 (84.7%) scored as MSI-high using the 24-marker and 54-marker panels, respectively. The concordance between the MSI assays and immunohistochemistry was 70.6% (p = 0.003), 87.5% (p = 0.039), and 90.3% (p = 1.00) for the Promega assay, the 24-marker assay, and the 54-marker assay, respectively. Of the 11 tumors with retained MMR protein expression, four were MSI-low/MSI-high or MSI-high by the Promega assay or one of the sequencing-based assays. Conclusion: Our results show that Lynch syndrome-associated urothelial cancers frequently had loss of MMR protein expression. The Promega MSI assay was significantly less sensitive, but the 54-marker sequencing-based MSI analysis showed no significant difference compared to immunohistochemistry. Data from this study alongside previous studies, suggest that universal MMR deficiency testing of newly diagnosed urothelial cancers, using immunohistochemistry and/or sequencing-based MSI analysis of sensitive markers, offer a potentially useful approach to identification of Lynch syndrome cases. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Caribbean Ornithology is the property of Society for the Conservation & Study of Caribbean Birds and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A previous literature review found at least 4/9 (>=44.4%) CMMRD-associated ALL were T-ALL [[1]], and 8/88 (9.1%, 95% CI: 0.4-17.1%) childhood T-LBL patients were diagnosed with CMMRD in a consecutive series between 2007 and 2020 [[15]], suggesting an association of CMMRD with T cell lineage malignancies. For example, PCR-fragment length analysis has been shown to be insensitive to MSH6 deficiency in ALL relapse samples [[3]], and detected increased MSI in only 27% of CMMRD haematological malignancies and in 0% of non-neoplastic CMMRD tissues [[9]]. Here, 1/17 (5.9%, 95% CI: 0.2-28.7%) ALL patients with SMN had CMMRD, which is similar to the 14/189 (7.4%, 95% CI: 4.1-12.1%) pediatric non-Hodgkin lymphoma patients with SMN who had CMMRD in another recent study [[16]]. Constitutional mismatch repair deficiency (CMMRD, MIM #276300) is a rare, recessive pediatric and adolescent cancer syndrome, caused by pathogenic variants in a mismatch repair (MMR) gene: I MLH1 i , I MSH2 i , I MSH6 i , or I PMS2 i . [Extracted from the article]