% IMPORTANT: The following is UTF-8 encoded. This means that in the presence % of non-ASCII characters, it will not work with BibTeX 0.99 or older. % Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or % “biber”. @ARTICLE{Friker:298422, author = {L. L. Friker and T. Perwein and A. Waha and E. Dörner and R. Klein and M. Blattner-Johnson$^*$ and J. P. Layer and D. Sturm$^*$ and G. Nussbaumer and R. Kwiecien and I. Spier and S. Aretz and K. Kerl and U. Hennewig and M. Rohde and A. Karow and I. Bluemcke and A. K. Schmitz and H. Reinhard and P. Hernáiz Driever and S. Wendt and A. Weiser and A. S. Guerreiro Stücklin and N. U. Gerber and A. O. von Bueren and C. Khurana and N. Jorch and M. Wiese and C. P. Kratz and M. Eyrich and M. Karremann and U. Herrlinger and M. Hölzel and D. T. W. Jones$^*$ and M. Hoffmann and T. Pietsch and G. H. Gielen and C. M. Kramm}, title = {{MSH}2, {MSH}6, {MLH}1, and {PMS}2 immunohistochemistry as highly sensitive screening method for {DNA} mismatch repair deficiency syndromes in pediatric high-grade glioma.}, journal = {Acta neuropathologica}, volume = {149}, number = {1}, issn = {0001-6322}, address = {Heidelberg}, publisher = {Springer}, reportid = {DKFZ-2025-00278}, pages = {11}, year = {2025}, abstract = {Pediatric high-grade glioma (pedHGG) can occur as first manifestation of cancer predisposition syndromes resulting from pathogenic germline variants in the DNA mismatch repair (MMR) genes MSH2, MSH6, MLH1, and PMS2. The aim of this study was to establish a generalized screening for Lynch syndrome and constitutional MMR deficiency (CMMRD) in pedHGG patients, as the detection of MMR deficiencies (MMRD) may enable the upfront therapeutic use of checkpoint inhibitors and identification of variant carriers in the patients' families. We prospectively enrolled 155 centrally reviewed primary pedHGG patients for MMR-immunohistochemistry (IHC) as part of the HIT-HGG-2013 trial protocol. MMR-IHC results were subsequently compared to independently collected germline sequencing data (whole exome sequencing or pan-cancer DNA panel next-generation sequencing) available in the HIT-HGG-2013, INFORM, and MNP2.0 trials. MMR-IHC could be successfully performed in 127/155 tumor tissues. The screening identified all present cases with Lynch syndrome or CMMRD $(5.5\%).$ In addition, MMR-IHC also detected cases with exclusive somatic MMR gene alterations $(2.3\%),$ including MSH2 hypermethylation as an alternative epigenetic silencing mechanism. Most of the identified pedHGG MMRD patients had no family history of MMRD, and thus, they represented index patients in their families. Cases with regular protein expression in MMR-IHC never showed evidence for MMRD in DNA sequencing. In conclusion, MMR-IHC presents a cost-effective, relatively widely available, and fast screening method for germline MMRD in pedHGG with high sensitivity $(100\%)$ and specificity $(96\%).$ Given the relatively high prevalence of previously undetected MMRD cases among pedHGG patients, we strongly recommend incorporating MMR-IHC into routine diagnostics.}, keywords = {Humans / Mismatch Repair Endonuclease PMS2: genetics / Mismatch Repair Endonuclease PMS2: metabolism / MutL Protein Homolog 1: genetics / MutS Homolog 2 Protein: genetics / MutS Homolog 2 Protein: metabolism / Female / Brain Neoplasms: genetics / Brain Neoplasms: pathology / Child / DNA-Binding Proteins: genetics / DNA-Binding Proteins: metabolism / Male / Glioma: genetics / Glioma: pathology / Glioma: metabolism / Immunohistochemistry: methods / Adolescent / DNA Mismatch Repair: genetics / Child, Preschool / Neoplastic Syndromes, Hereditary: genetics / Neoplastic Syndromes, Hereditary: diagnosis / Colorectal Neoplasms, Hereditary Nonpolyposis: genetics / Colorectal Neoplasms, Hereditary Nonpolyposis: pathology / Colorectal Neoplasms, Hereditary Nonpolyposis: diagnosis / Infant / Germ-Line Mutation: genetics / Colorectal Neoplasms / Constitutional mismatch repair deficiency (Other) / Immunohistochemistry (Other) / Lynch syndrome (Other) / Pediatric high-grade glioma (Other) / Mismatch Repair Endonuclease PMS2 (NLM Chemicals) / PMS2 protein, human (NLM Chemicals) / MutL Protein Homolog 1 (NLM Chemicals) / MutS Homolog 2 Protein (NLM Chemicals) / MSH2 protein, human (NLM Chemicals) / DNA-Binding Proteins (NLM Chemicals) / G-T mismatch-binding protein (NLM Chemicals) / MLH1 protein, human (NLM Chemicals)}, cin = {B360 / HD01}, ddc = {610}, cid = {I:(DE-He78)B360-20160331 / I:(DE-He78)HD01-20160331}, pnm = {312 - Funktionelle und strukturelle Genomforschung (POF4-312)}, pid = {G:(DE-HGF)POF4-312}, typ = {PUB:(DE-HGF)16}, pubmed = {pmid:39894875}, doi = {10.1007/s00401-025-02846-x}, url = {https://inrepo02.dkfz.de/record/298422}, }