Background: Lynch syndrome represents one of the most common cancer predispositions worldwide and is caused by germline pathogenic variants (PV) in DNA mismatch repair (MMR) genes. We repeatedly identified a PV in the MMR gene PMS2, c.1831dup, accounting for 27% of all Swiss PMS2 PV index patients identified. Notably, 2/18 index patients had been diagnosed with colorectal cancer (CRC) before age 30.
Methods: In this study, we investigated if this PV could (i) represent a founder variant by haplotype analysis and (ii) be associated with a more severe clinical phenotype.
Results: Haplotype analysis identified a shared common region of about 0.7 Mb/1.3 cM in 13 (81%) out of 16 index patients. Genotype-phenotype correlations, combining data from the 18 Swiss and 18 literature-derived PMS2 c.1831dup PV index patients and comparing them to 43 Swiss index patients carrying other PMS2 PVs, indicate that the PMS2 c.1831dup variant may be associated with earlier (<50 y) age at CRC diagnosis (55% vs. 29%, respectively; p = 0.047). Notably, 30% (9/30) of cancers from c.1831dup carriers displayed atypical MMR protein expression patterns on immunohistochemistry.
Conclusion: Our results suggest that the PMS2 c.1831dup PV represents a, probably ancient, founder mutation and is possibly associated with an earlier CRC diagnosis compared to other PMS2 PVs.
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http://dx.doi.org/10.1002/mgg3.2360 | DOI Listing |
In eukaryotes, mismatch repair begins with M ut S h omolog (MSH) complexes, which scan newly replicated DNA for mismatches. Upon mismatch detection, MSH complexes recruit the PCNA- stimulated endonuclease Mlh1-Pms1/PMS2 (yeast/human), which nicks the DNA to allow downstream proteins to remove the mismatch. Past work has shown that although Mlh1-Pms1 is an ATPase and this activity is important , ATP is not required to nick DNA.
View Article and Find Full Text PDFZhonghua Bing Li Xue Za Zhi
February 2025
Department of Pathology, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008, China.
To investigate whether the immunohistochemical results of two markers PMS2 and MSH6 (2-MMR) could replace the four markers MLH1, PMS2, MSH2 and MSH6 (4-MMR) to detect mismatch repair deficient (dMMR) cancers. A retrospective analysis was conducted with summary of immunohistochemical data from 7 867 cases of gastric cancer, colorectal cancer, endometrial cancer, and other diseases in the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China, from March 2018 to March 2023. The consistency of 2-MMR and 4-MMR results was examined.
View Article and Find Full Text PDFMedicina (Kaunas)
January 2025
Department of Surgery, Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, 050474 Bucharest, Romania.
In today's world, with its continuing advancements in genetics, the identification of Lynch syndrome (LS) increasingly relies on sophisticated genetic testing techniques. Most guidelines recommend a tailored surveillance program, as well as personalized prophylactic and therapeutic approaches, according to the type of dMMR gene mutation. Carriers of path_MLH1 and path_MSH2 genes have a higher risk of developing colorectal cancer (CRC), despite intensive colonoscopic surveillance.
View Article and Find Full Text PDFHered Cancer Clin Pract
January 2025
Division of Cancer and Genetics, Cardiff University School of Medicine, Heath Park, Cardiff, CF14 4XN, UK.
Carcinogenesis encompasses processes that lead to increased mutation rates, enhanced cellular division (tumour growth), and invasive growth. Colorectal cancer (CRC) carcinogenesis in carriers of pathogenic APC (path_APC) and pathogenic mismatch repair gene (path_MMR) variants is initiated by a second hit affecting the corresponding wild-type allele. In path_APC carriers, second hits result in the development of multiple adenomas, with CRC typically emerging after an additional 20 years.
View Article and Find Full Text PDFiScience
January 2025
Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
We present a study of rare germline predisposition variants in 954 unrelated individuals with multiple myeloma (MM) and 82 MM families. Using a candidate gene approach, we identified such variants across all age groups in 9.1% of sporadic and 18% of familial cases.
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