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3 results on '"Tops CMJ"'

1. Constitutional mismatch repair deficiency syndrome with atypical features caused by a homozygous MLH1 missense variant (c.1918C>A, p.(Pro640Thr)): a case report.

Author

Akrout F, Achour A, Tops CMJ, Gallon R, Meddeb R, Achoura S, Ben Rekaya M, Hamdeni E, Rammeh S, Chkili R, Mansouri N, Belguith N, and Mrad R

Abstract

Constitutional mismatch repair deficiency (CMMRD) syndrome is a rare autosomal recessive genetic disorder caused by biallelic germline mutations in one of the mismatch repair genes. Carriers are at exceptionally high risk for developing, typically in early life, hematological and brain malignancies, as well as cancers observed in Lynch syndrome. We report a homozygous MLH1 missense variant (c.1918C>A p.(Pro640Thr)) in a Tunisian patient with CMMRD syndrome and a family history of early-age colorectal cancer. The proband presented initially with colonic oligopolyposis and adenosquamous carcinoma of the caecum. He later developed several malignancies, including undifferentiated carcinoma of the parotid, grade 4 IDH-mutant astrocytoma, and ampulla of Vater adenocarcinoma. The patient was older than typical for this disease and had a remarkably prolonged survival despite developing four distinct aggressive malignancies. The current report highlights the challenges in assessing the pathogenicity of the identified variant and the remarkable phenotypic diversity in CMMRD., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Akrout, Achour, Tops, Gallon, Meddeb, Achoura, Ben Rekaya, Hamdeni, Rammeh, Chkili, Mansouri, Belguith and Mrad.)

Published
2023
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2. Unexplained mismatch repair deficiency: Case closed.

Author

Eikenboom EL, Moen S, van Leeuwen L, Geurts-Giele WRR, Tops CMJ, van Ham TJ, Dinjens WNM, Dubbink HJ, Spaander MCW, and Wagner A

Subjects
Humans, Colorectal Neoplasms diagnosis, Neoplastic Syndromes, Hereditary diagnosis, Colorectal Neoplasms, Hereditary Nonpolyposis diagnosis, Brain Neoplasms
Abstract

To identify Lynch syndrome (LS) carriers, DNA mismatch repair (MMR) immunohistochemistry (IHC) is performed on colorectal cancers (CRCs). Upon subsequent LS diagnostics, MMR deficiency (MMRd) sometimes remains unexplained (UMMRd). Recently, the importance of complete LS diagnostics to explain UMMRd, involving MMR methylation, germline, and somatic analyses, was stressed. To explore why some MMRd CRCs remain unsolved, we performed a systematic review of the literature and mapped patients with UMMRd diagnosed in our center. A systematic literature search was performed in Ovid Medline, Embase, Web of Science, Cochrane CENTRAL, and Google Scholar for articles on UMMRd CRCs after complete LS diagnostics published until December 15, 2021. Additionally, UMMRd CRCs diagnosed in our center since 1993 were mapped. Of 754 identified articles, 17 were included, covering 74 patients with UMMRd. Five CRCs were microsatellite stable. Upon complete diagnostics, 39 patients had single somatic MMR hits, and six an MMR germline variant of unknown significance (VUS). Ten had somatic pathogenic variants (PVs) in POLD1 , MLH3 , MSH3 , and APC . The remaining 14 patients were the only identifiable cases in the literature without a plausible identified cause of the UMMRd. Of those, nine were suspected to have LS. In our center, complete LS diagnostics in approximately 5,000 CRCs left seven MMRd CRCs unexplained. All had a somatic MMR hit or MMR germline VUS, indicative of a missed second MMR hit. In vitually all patients with UMMRd, complete LS diagnostics suggest MMR gene involvement. Optimizing detection of currently undetectable PVs and VUS interpretation might explain all UMMRd CRCs, considering UMMRd a case closed., Competing Interests: The authors declare no competing interests., (© 2022 The Authors.)

Published
2022
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3. Use of sanger and next-generation sequencing to screen for mosaic and intronic APC variants in unexplained colorectal polyposis patients.

Author

Elsayed FA, Tops CMJ, Nielsen M, Morreau H, Hes FJ, and van Wezel T

Subjects
Genes, APC, Germ-Line Mutation, High-Throughput Nucleotide Sequencing, Humans, Mutation, Adenomatous Polyposis Coli genetics, Adenomatous Polyposis Coli pathology, Adenomatous Polyposis Coli Protein genetics, Colorectal Neoplasms genetics
Abstract

In addition to classic germline APC gene variants, APC mosaicism and deep intronic germline APC variants have also been reported to be causes of adenomatous polyposis. In this study, we investigated 80 unexplained colorectal polyposis patients without germline pathogenic variants in known polyposis predisposing genes to detect mosaic and deep intronic APC variants. All patients developed more than 50 colorectal polyps, with adenomas being predominantly observed. To detect APC mosaicism, we performed next-generation sequencing (NGS) in leukocyte DNA. Furthermore, using Sanger sequencing, the cohort was screened for the following previously reported deep intronic pathogenic germline APC variants: c.1408 + 731C > T, p.(Gly471Serfs*55), c.1408 + 735A > T, p.(Gly471Serfs*55), c.1408 + 729A > G, p.(Gly471Serfs*55) and c.532-941G > A, p.(Phe178Argfs*22). We did not detect mosaic or intronic APC variants in the screened unexplained colorectal polyposis patients. The results of this study indicate that the deep intronic APC variants investigated in this study are not a cause of colorectal polyposis in this Dutch population. In addition, NGS did not detect any further mosaic variants in our cohort., (© 2021. The Author(s).)

Published
2022
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