Abstract
A high colorectal cancer (CRC) incidence is observed in Tunisia, with a relatively high proportion of patients developing CRC before the age of 40. While this suggests a genetic susceptibility, only a few Tunisian Lynch Syndrome families have been described. In this study we aimed to identify the underlying genetic cause in 32 patients with early onset CRC and/or a positive family history. Of twenty-four patients’ tumor or biopsies could be analyzed with immunohistochemical staining to detect loss of expression of one of the MMR proteins. Ten tumors showed loss of expression, of which one tumor was from a patient where a germline pathogenic MSH2 variant was detected previously with Sanger sequencing. Next generation sequencing of the MMR, POLE and POLD1 genes was performed in leukocyte and tumor DNA of the remaining nine patients, as well as in two patients with MMR-proficient tumors, but with severe family history. In six of 11 patients a germline variant was detected in MLH1 (n = 5) or MSH2 (n = 1). Two of six patients were from the same family and both were found to carry a novel in-frame MLH1 deletion, predicted to affect MLH1 function. All MLH1 variant carriers had loss of heterozygosity with retention of the variant in the tumors, while a somatic pathogenic variant was detected in the patient with the germline MSH2 variant.
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References
Lynch HT, de la Chapelle A (2003) Hereditary colorectal cancer. N Engl J Med 348:919–932
Leach FS, Nicolaides NC, Papadopoulos N et al (1993) Mutations of a mutS homolog in hereditary nonpolyposis colorectal cancer. Cell 75:1215–1225
Nicolaides NC, Papadopoulos N, Liu B et al (1994) Mutations of two PMS homologues in hereditary nonpolyposis colon cancer. Nature 371:75–80
Peltomäki P (2001) Deficient DNA mismatch repair. Hum Mol Genet 7:735–740
Ligtenberg MJ, Kuiper RP, Chan TL et al (2009) Heritable somatic methylation and inactivation of MSH2 in families with Lynch syndrome due to deletion of the 3’ exons of TACSTD1. Nat Genet 41:112–117
Mensenkamp AR, Vogelaar IP, van Zelst-Stams WA et al (2014) Somatic mutations in MLH1 and MSH2 are a frequent cause of mismatch-repair deficiency in Lynch syndrome-like tumors. Gastroenterology 146(643–646):e8
Geurts-Giele WR, Leenen CH, Dubbink HJ et al (2014) Somatic aberrations of mismatch repair genes as a cause of microsatellite-unstable cancers. J Pathol 234:548–559
Jansen AM, Van Wezel T, Van den Akker BE et al (2016) Combined mismatch repair and POLE/POLD1 defects explain unresolved suspected Lynch Syndrome cancers. Eur J Hum Genet 24:1089–1092
Herman JG, Umar A, Polyak K et al (1998) Incidence and functional consequences of hMLH1 promoter hypermethylation in colorectal carcinoma. Proc Natl Acad Sci USA 95:6870–6875
Moussa SA, Moussa A, Kourda N et al (2011) Lynch syndrome in Tunisia: first description of clinical features and germline mutations. Int J Colorectal Dis 26:455–467
Khiari H, Ben Ayoub HW, Ben Khadhra H et al (2017) Colorectal cancer incidence trend and projections in Tunisia (1994–2024). Asian Pac J Cancer Prev 18(10):2733–2739
Bjerrum A, Andersen O, Fischer A et al (2016) Colorectal cancer mortality 10 years after a single round of guaiac faecal occult blood test (gFOBT) screening: experiences from a Danish screening cohort. BMJ Open Gastroenterol 3(1):e000120
Elsayed FA, Kets CM, Ruano D et al (2015) Germline variants in POLE are associated with early onset mismatch repair deficient colorectal cancer. Eur J Hum Genet 23:1080–1084
Mili A, Ben Charfeddine I, Amara A et al (2012) A c.3216_3217delGA mutation in AGL gene in Tunisian patients with a glycogen storage disease type III: evidence of a founder effect. Clin Genet 82(6):534–539
De Jong AE, van Puijenbroek M, Hendriks Y et al (2004) Microsatellite instability, immunohistochemistry, and additional PMS2 staining in suspected hereditary nonpolyposis colorectal cancer. Clin Cancer Res 10:972–980
van Eijk R, Stevens L, Morreau H et al (2013) Assessment of a fully automated high-throughput DNA extraction method from formalin-fixed, paraffin-embedded tissue for KRAS, and BRAF somatic mutation analysis. Exp Mol Pathol 94(1):121–125
Schwarz JM, Cooper DN, Schuelke M et al (2014) MutationTaster2: mutation prediction for the deep-sequencing age. Nat Methods 11(4):361–362
Adzhubei IA, Schmidt S, Peshkin L et al (2010) A method and server for predicting damaging missense mutations. Nat Methods 7(4):248–249
The UniProt Consortium (2017) UniProt: the universal protein knowledgebase. Nucleic Acids Res 45:D158–D169
Takahashi M, Shimodaira H, Andreutti-Zaugg C et al (2007) Functional analysis of human MLH1 variants using yeast and in vitro mismatch repair assays. Cancer Res 67(10):4595–4604
Ellison AR, Lofing J, Bitter GA (2004) Human MutL homolog (MLH1) function in DNA mismatch repair: a prospective screen for missense mutations in the ATPase domain. Nucleic Acids Res 32(18):5321–5338
Raevaara TE, Gerdes AM, Lönnqvist KE et al (2004) HNPCC mutation MLH1 P648S makes the functional protein unstable, and homozygosity predisposes to mild neurofibromatosis type 1. Genes Chromosom Cancer 40:261–265
Drost M, Je Zonneveld, van Dijk L et al (2010) A cell-free assay for the functional analysis of variants of the mismatch repair protein MLH1. Hum Mutat 31:247–253
Overbeek L, Kets CM, Hebeda KM et al (2007) Patients with an unexplained microsatellite instable tumour have a low risk of familial cancer. Br J Cancer 96:1605–1612
Hampel H, Pearlman R, Beightol M et al (2018) Assessment of tumor sequencing as a replacement for lynch syndrome screening and current molecular tests for patients with colorectal cancer. JAMA Oncol 4(6):806–813
Lindor NM, Rabe K, Petersen GM et al (2005) Lower cancer incidence in Amsterdam-I criteria families without mismatch repair deficiency - familial colorectal cancer type X. Jama-J Am Med Assoc 293:1979–1985
Balmana J, Castells A, Cervantes A et al (2010) Familial colorectal cancer risk: ESMO clinical practice guidelines. Ann Oncol 5:v78–v81
Shiovitz S, Copeland WK, Passarelli MN et al (2014) Characterisation of familial colorectal cancer Type X, Lynch syndrome, and non-familial colorectal cancer. Br J Cancer 111:598–602
Schulz E, Klampfl P, Holzapfel S et al (2014) Germline variants in the SEMA4A gene predispose to familial colorectal cancer type X. Nat Commun 5:5191
Briggs S, Tomlinson I (2013) Germline and somatic polymerase epsilon and delta mutations define a new class of hypermutated colorectal and endometrial cancers. J Pathol 230:148–153
Palles C, Cazier JB, Howarth KM et al (2013) Germline mutations affecting the proofreading domains of POLE and POLD1 predispose to colorectal adenomas and carcinomas. Nat Genet 45:136–144
Heitzer E, Tomlinson I (2014) Replicative DNA polymerase mutations in cancer. Curr Opin Genet Dev 24:107–113
Stoffel EM, Koeppe E, Everett J et al (2017) Germline genetic features of young individuals with colorectal cancer. Gastroenterology 154(4):897–905
Acknowledgements
We thank all team members of Human Cytogenetic, Molecular Genetics and Biology of Reproduction laboratory, Farhat HACHED Hospital Sousse-Tunisia, and the Molecular Diagnostics of the Pathology department of the Leiden University Medical Center. Also, we thank all patients and their families for their contribution and great help.
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10689_2019_130_MOESM1_ESM.tif
Supplementary material 1—Presentation of suspected Lynch Syndrome patients tested by NGS. Pedigrees showing candidates with detected variants by MMR Panel and the segregation of the CRC in their families. CRC: Colorectal Carcinoma, BrC: Breast Cancer, Uter: Uterine Cancer, StC: Stomach Cancer, CHC: Hepatocarcinoma, BrnC:Brain Cancer ,LeukC: Leukemia Cancer, LunC:Lung Cancer.Age at diagnosis is mentioned with the type of the cancer; circles represent females; squares represent males; diamonds represent undisclosed gender; cross striped individuals are deceased. Black blocks present patients and family members with CRC, black right upper corner presents family member with Uter cancer, black left upper corners presents family member with StC , black right lower corner presents family member with BrC,black left lower corner presents family member with BrnC, left Black half presents family member with LeukC, right black half presents family member with LunC (TIFF 117 kb)
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Ben Sghaier, R., Jansen, A.M.L., Bdioui, A. et al. Targeted next generation sequencing screening of Lynch syndrome in Tunisian population. Familial Cancer 18, 343–348 (2019). https://doi.org/10.1007/s10689-019-00130-y
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DOI: https://doi.org/10.1007/s10689-019-00130-y