Diagnosis of Constitutional Mismatch Repair-Deficiency Syndrome Based on Microsatellite Instability and Lymphocyte Tolerance to Methylating Agents

• Published in: Gastroenterology Vol. 149; no. 4; pp. 1017 - 1029.e3
• Main Authors: Bodo, Sahra, Colas, Chrystelle, Buhard, Olivier, Collura, Ada, Tinat, Julie, Lavoine, Noémie, Guilloux, Agathe, Chalastanis, Alexandra, Lafitte, Philippe, Coulet, Florence, Buisine, Marie-Pierre, Ilencikova, Denisa, Ruiz-Ponte, Clara, Kinzel, Miriam, Grandjouan, Sophie, Brems, Hilde, Lejeune, Sophie, Blanché, Hélène, Wang, Qing, Caron, Olivier, Cabaret, Odile, Svrcek, Magali, Vidaud, Dominique, Parfait, Béatrice, Verloes, Alain, Knappe, Ulrich J., Soubrier, Florent, Mortemousque, Isabelle, Leis, Alexander, Auclair-Perrossier, Jessie, Frébourg, Thierry, Fléjou, Jean-François, Entz-Werle, Natacha, Leclerc, Julie, Malka, David, Cohen-Haguenauer, Odile, Goldberg, Yael, Gerdes, Anne-Marie, Fedhila, Faten, Mathieu-Dramard, Michèle, Hamelin, Richard, Wafaa, Badre, Gauthier-Villars, Marion, Bourdeaut, Franck, Sheridan, Eamonn, Vasen, Hans, Brugières, Laurence, Wimmer, Katharina, Muleris, Martine, Duval, Alex
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2015; Elsevier BV
• Subjects: Adaptor Proteins; Adaptor Proteins, Signal Transducing; Adaptor Proteins, Signal Transducing - genetics; Adenosine Triphosphatases; Adenosine Triphosphatases - genetics; Adult; Alkylating; Antineoplastic Agents; Antineoplastic Agents, Alkylating; Antineoplastic Agents, Alkylating - therapeutic use; Biomarkers; Biomarkers, Tumor; Biomarkers, Tumor - genetics; Brain Neoplasms; Brain Neoplasms - diagnosis; Brain Neoplasms - drug therapy; Brain Neoplasms - genetics; Brain Neoplasms - metabolism; Brain Neoplasms - pathology; Caco-2 Cells; Case-Control Studies; Colon Cancer; Colorectal Neoplasms; Colorectal Neoplasms - diagnosis; Colorectal Neoplasms - drug therapy; Colorectal Neoplasms - genetics; Colorectal Neoplasms - metabolism; Colorectal Neoplasms - pathology; Colorectal Neoplasms, Hereditary Nonpolyposis; Colorectal Neoplasms, Hereditary Nonpolyposis - diagnosis; Colorectal Neoplasms, Hereditary Nonpolyposis - drug therapy; Colorectal Neoplasms, Hereditary Nonpolyposis - genetics; Colorectal Neoplasms, Hereditary Nonpolyposis - metabolism; Colorectal Neoplasms, Hereditary Nonpolyposis - pathology; DNA Mutational Analysis; DNA Repair Enzymes; DNA Repair Enzymes - genetics; DNA-Binding Proteins; DNA-Binding Proteins - genetics; Drug Resistance; Drug Resistance, Neoplasm; Female; Functional Tests; Gastroenterology and Hepatology; Genetic Predisposition to Disease; Genetic Testing; Genetic Testing - methods; Germ-Line Mutation; HCT116 Cells; Hereditary; Hereditary Nonpolyposis; Heredity; Humans; Lymphocytes; Lymphocytes - drug effects; Lymphocytes - metabolism; Male; Methylation; Microsatellite Instability; Mismatch Repair Endonuclease PMS2; Multiplex Polymerase Chain Reaction; MutL Protein Homolog 1; MutS Homolog 2 Protein; MutS Homolog 2 Protein - genetics; Neoplasm; Neoplastic Syndromes; Neoplastic Syndromes, Hereditary; Neoplastic Syndromes, Hereditary - diagnosis; Neoplastic Syndromes, Hereditary - drug therapy; Neoplastic Syndromes, Hereditary - genetics; Neoplastic Syndromes, Hereditary - metabolism; Neoplastic Syndromes, Hereditary - pathology; Nuclear Proteins; Nuclear Proteins - genetics; Phenotype; Predictive Value of Tests; Predisposition; Reproducibility of Results; Signal Transducing; Transfection; Tumor; Young Adult; CMMRD; MSI; IHC; LS; Functional Tests; 6-TG; gMSI; MMR; evMSI; FAP; LCL; VUS; Colon Cancer; Predisposition; NF1; Tumor; PBLs; MNNG; microsatellite instability; ex vivo microsatellite instability; mismatch repair; lymphoblastoid cell line; immunohistochemistry; Lynch syndrome; variant of unknown functional significance; germline microsatellite instability; peripheral blood lymphocytes; constitutional mismatch repair; 6-thioguanine; N-methyl- N-nitro- N-nitrosoguanidine; neurofibromatosis type 1; familial adenomatous polyposis
• ISSN: 0016-5085; 1528-0012; 1528-0012
• DOI: 10.1053/j.gastro.2015.06.013

Patients with bi-allelic germline mutations in mismatch repair (MMR) genes (MLH1, MSH2, MSH6, or PMS2) develop a rare but severe variant of Lynch syndrome called constitutional MMR deficiency (CMMRD). This syndrome is characterized by early-onset colorectal cancers, lymphomas or leukemias, and brain tumors. There is no satisfactory method for diagnosis of CMMRD because screens for mutations in MMR genes are noninformative for 30% of patients. MMR-deficient cancer cells are resistant to genotoxic agents and have microsatellite instability (MSI), due to accumulation of errors in repetitive DNA sequences. We investigated whether these features could be used to identify patients with CMMRD. We examined MSI by PCR analysis and tolerance to methylating or thiopurine agents (functional characteristics of MMR-deficient tumor cells) in lymphoblastoid cells (LCs) from 3 patients with CMMRD and 5 individuals with MMR-proficient LCs (controls). Using these assays, we defined experimental parameters that allowed discrimination of a series of 14 patients with CMMRD from 52 controls (training set). We then used the same parameters to assess 23 patients with clinical but not genetic features of CMMRD. In the training set, we identified parameters, based on MSI and LC tolerance to methylation, that detected patients with CMMRD vs controls with 100% sensitivity and 100% specificity. Among 23 patients suspected of having CMMRD, 6 had MSI and LC tolerance to methylation (CMMRD highly probable), 15 had neither MSI nor LC tolerance to methylation (unlikely to have CMMRD), and 2 were considered doubtful for CMMRD based on having only 1 of the 2 features. The presence of MSI and tolerance to methylation in LCs identified patients with CMMRD with 100% sensitivity and specificity. These features could be used in diagnosis of patients.