BRAF and MLH1 Analysis Algorithm for the Evaluation of Lynch Syndrome Risk in Colorectal Carcinoma Patients: Evidence-Based Data from the Analysis of 100 Consecutive Cases

settingsOrder Article Reprints Open AccessFeature PaperArticle BRAF and MLH1 Analysis Algorithm for the Evaluation of Lynch Syndrome Risk in Colorectal Carcinoma Patients: Evidence-Based Data from the Analysis of 100 Consecutive Cases by Thais Maloberti 1,2,†ORCID,Antonio De Leo 1,2,†ORCID,Viviana Sanza 2,Lidia Merlo 2,Michela Visani 1ORCID,Giorgia Acquaviva 1,Sara Coluccelli 1,2ORCID,Annalisa Altimari 2,3,Elisa Gruppioni 2,3,Stefano Zagnoni 2,3,Daniela Turchetti 4,Sara Miccoli 4,Michelangelo Fiorentino 5,6ORCID,Antonietta D’Errico 3ORCID,Dario de Biase 7,*,‡ORCID andGiovanni Tallini 1,2,‡ORCID 1 Department of Experimental, Diagnostic and Specialty Medicine, Anatomic Pathology Unit-University of Bologna Medical Center, 40138 Bologna, Italy 2 Solid Tumor Molecular Pathology Laboratory, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy 3 Department of Pathology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy 4 Unit of Medical Genetics, IRCCS (Istituto di Ricovero e Cura a Carattere Scientifico), Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy 5 Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, 40138 Bologna, Italy 6 Pathology Department, Maggiore Hospital, 40133 Bologna, Italy 7 Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy * Author to whom correspondence should be addressed. † These authors contributed equally to this work. ‡ These authors contributed equally to this work. J. Mol. Pathol. 2022, 3(3), 115-124; https://doi.org/10.3390/jmp3030011 Received: 30 March 2022 / Revised: 27 May 2022 / Accepted: 21 June 2022 / Published: 25 June 2022 (This article belongs to the Collection Feature Papers in Journal of Molecular Pathology) Download Browse Figures Versions Notes Abstract Several causes may lead to CRC, either extrinsic (sporadic forms) or genetic (hereditary forms), such as Lynch syndrome (LS). Most sporadic deficient mismatch repair (dMMR) CRC cases are characterized by the methylation of the MLH1 promoter gene and/or BRAF gene mutations. Usually, the first test performed is the mismatch repair deficiency analysis. If a tumor shows a dMMR, BRAF mutations and then the MLH1 promoter methylation status have to be assessed, according to the ACG/ASCO screening algorithm. In this study, 100 consecutive formalin-fixed and paraffin-embedded samples of dMMR CRC were analyzed for both BRAF mutations and MLH1 promoter methylation. A total of 47 (47%) samples were BRAF p.V600E mutated, while MLH1 promoter methylation was found in 77 cases (77.0%). The pipeline “BRAF-followed-by-MLH1-analysis” led to a total of 153 tests, while the sequence “MLH1-followed-by-BRAF-analysis” resulted in a total of 123 tests. This study highlights the importance of performing MLH1 analysis in LS screening of BRAF-WT specimens before addressing patients to genetic counseling. We show that MLH1 analysis performs better as a first-line test in the screening of patients with LS risk than first-line BRAF analysis. Our data indicate that analyzing MLH1 methylation as a first-line test is more cost-effective.