Publications by authors named "Stefanie Holzapfel"

23 Publications

  • Page 1 of 1

Uptake of hysterectomy and bilateral salpingo-oophorectomy in carriers of pathogenic mismatch repair variants: a Prospective Lynch Syndrome Database report.

Eur J Cancer 2021 May 17;148:124-133. Epub 2021 Mar 17.

Medizinische Klinik und Poliklinik IV, Campus Innenstadt, Klinikum der Universität München, Munich, Germany; MGZ- Medical Genetics Center, Munich, Germany; The International Society for Gastrointestinal Hereditary Tumours (InSiGHT), The Polyposis Registry, St Mark's Hospital, Watford Road, Harrow, Middlesex, HA1 3UJ, UK; European Hereditary Tumour Group (EHTG), C/o Lindsays, Caledonian Exchange, 19A Canning Street, Edinburgh, EH3 8HE, United Kingdom.

Purpose: This study aimed to report the uptake of hysterectomy and/or bilateral salpingo-oophorectomy (BSO) to prevent gynaecological cancers (risk-reducing surgery [RRS]) in carriers of pathogenic MMR (path_MMR) variants.

Methods: The Prospective Lynch Syndrome Database (PLSD) was used to investigate RRS by a cross-sectional study in 2292 female path_MMR carriers aged 30-69 years.

Results: Overall, 144, 79, and 517 carriers underwent risk-reducing hysterectomy, BSO, or both combined, respectively. Two-thirds of procedures before 50 years of age were combined hysterectomy and BSO, and 81% of all procedures included BSO. Risk-reducing hysterectomy was performed before age 50 years in 28%, 25%, 15%, and 9%, and BSO in 26%, 25%, 14% and 13% of path_MLH1, path_MSH2, path_MSH6, and path_PMS2 carriers, respectively. Before 50 years of age, 107 of 188 (57%) BSO and 126 of 204 (62%) hysterectomies were performed in women without any prior cancer, and only 5% (20/392) were performed simultaneously with colorectal cancer (CRC) surgery.

Conclusion: Uptake of RRS before 50 years of age was low, and RRS was rarely undertaken in association with surgical treatment of CRC. Uptake of RRS aligned poorly with gene- and age-associated risk estimates for endometrial or ovarian cancer that were published recently from PLSD and did not correspond well with current clinical guidelines. The reasons should be clarified. Decision-making on opting for or against RRS and its timing should be better aligned with predicted risk and mortality for endometrial and ovarian cancer in Lynch syndrome to improve outcomes.
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http://dx.doi.org/10.1016/j.ejca.2021.02.022DOI Listing
May 2021

Risk-reducing hysterectomy and bilateral salpingo-oophorectomy in female heterozygotes of pathogenic mismatch repair variants: a Prospective Lynch Syndrome Database report.

Genet Med 2021 Apr 1;23(4):705-712. Epub 2020 Dec 1.

Medizinische Klinik und Poliklinik IV, Campus Innenstadt, Klinikum der Universität München, Munich, Germany.

Purpose: To determine impact of risk-reducing hysterectomy and bilateral salpingo-oophorectomy (BSO) on gynecological cancer incidence and death in heterozygotes of pathogenic MMR (path_MMR) variants.

Methods: The Prospective Lynch Syndrome Database was used to investigate the effects of gynecological risk-reducing surgery (RRS) at different ages.

Results: Risk-reducing hysterectomy at 25 years of age prevents endometrial cancer before 50 years in 15%, 18%, 13%, and 0% of path_MLH1, path_MSH2, path_MSH6, and path_PMS2 heterozygotes and death in 2%, 2%, 1%, and 0%, respectively. Risk-reducing BSO at 25 years of age prevents ovarian cancer before 50 years in 6%, 11%, 2%, and 0% and death in 1%, 2%, 0%, and 0%, respectively. Risk-reducing hysterectomy at 40 years prevents endometrial cancer by 50 years in 13%, 16%, 11%, and 0% and death in 1%, 2%, 1%, and 0%, respectively. BSO at 40 years prevents ovarian cancer before 50 years in 4%, 8%, 0%, and 0%, and death in 1%, 1%, 0%, and 0%, respectively.

Conclusion: Little benefit is gained by performing RRS before 40 years of age and premenopausal BSO in path_MSH6 and path_PMS2 heterozygotes has no measurable benefit for mortality. These findings may aid decision making for women with LS who are considering RRS.
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http://dx.doi.org/10.1038/s41436-020-01029-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8026395PMC
April 2021

Cancer risks in Lynch syndrome, Lynch-like syndrome, and familial colorectal cancer type X: a prospective cohort study.

BMC Cancer 2020 May 24;20(1):460. Epub 2020 May 24.

Institute for Medical Informatics, Statistics and Epidemiology (IMISE), University of Leipzig, Leipzig, Germany.

Background: Individuals with pathogenic germline variants in DNA mismatch repair (MMR) genes are at increased risk of developing colorectal, endometrial and other cancers (Lynch syndrome, LS). While previous studies have extensively described cancer risks in LS, cancer risks in individuals from families without detectable MMR gene defects despite MMR deficiency (Lynch-like syndrome, LLS), and in individuals from families fulfilling the Amsterdam-II criteria without any signs of MMR deficiency (familial colorectal cancer type X, FCCX) are less well studied. The aim of this prospective study was to characterise the risk for different cancer types in LS, LLS, and FCCX, and to compare these with the cancer risks in the general population.

Methods: Data was taken from the registry of the German Consortium for Familial Intestinal Cancer, where individuals were followed up prospectively within the framework of an intensified surveillance programme at recommended annual examination intervals. A total of 1120 LS, 594 LLS, and 116 FCCX individuals were analysed. From this total sample, eight different cohorts were defined, in which age-dependent cumulative risks and standardised incidence ratios were calculated regarding the first incident occurrence of any, colorectal, stomach, small bowel, urothelial, female breast, ovarian, and endometrial cancer, separately for LS, LLS, and FCCX.

Results: The number of individuals at risk for first incident cancer ranged from 322 to 1102 in LS, 120 to 586 in LLS, and 40 to 116 in FCCX, depending on the cancer type of interest. For most cancer types, higher risks were observed in LS compared to LLS, FCCX, and the general population. Risks for any, colorectal, stomach, urothelial, and endometrial cancer were significantly higher in LLS compared to the general population. No significantly increased risks could be detected in FCCX compared to LLS patients, and the general population. Colorectal and endometrial cancer risks tended to be higher in LLS than in FCCX.

Conclusions: The characterisation of cancer risks in patients with LLS and FCCX is important to develop appropriate surveillance programmes for these specific intermediate risk groups. Larger prospective studies are needed to obtain more precise risk estimates.
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http://dx.doi.org/10.1186/s12885-020-06926-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7245918PMC
May 2020

Associations of Pathogenic Variants in MLH1, MSH2, and MSH6 With Risk of Colorectal Adenomas and Tumors and With Somatic Mutations in Patients With Lynch Syndrome.

Gastroenterology 2020 04 8;158(5):1326-1333. Epub 2020 Jan 8.

Department of Gastroenterology & Hepatology, Leiden University Medical Center, Leiden, The Netherlands.

Background & Aims: Lynch syndrome is caused by variants in DNA mismatch repair (MMR) genes and associated with an increased risk of colorectal cancer (CRC). In patients with Lynch syndrome, CRCs can develop via different pathways. We studied associations between Lynch syndrome-associated variants in MMR genes and risks of adenoma and CRC and somatic mutations in APC and CTNNB1 in tumors in an international cohort of patients.

Methods: We combined clinical and molecular data from 3 studies. We obtained clinical data from 2747 patients with Lynch syndrome associated with variants in MLH1, MSH2, or MSH6 from Germany, the Netherlands, and Finland who received at least 2 surveillance colonoscopies and were followed for a median time of 7.8 years for development of adenomas or CRC. We performed DNA sequence analyses of 48 colorectal tumors (from 16 patients with mutations in MLH1, 29 patients with mutations in MSH2, and 3 with mutations in MSH6) for somatic mutations in APC and CTNNB1.

Results: Risk of advanced adenoma in 10 years was 17.8% in patients with pathogenic variants in MSH2 vs 7.7% in MLH1 (P < .001). Higher proportions of patients with pathogenic variants in MLH1 or MSH2 developed CRC in 10 years (11.3% and 11.4%) than patients with pathogenic variants in MSH6 (4.7%) (P = .001 and P = .003 for MLH1 and MSH2 vs MSH6, respectively). Somatic mutations in APC were found in 75% of tumors from patients with pathogenic variants in MSH2 vs 11% in MLH1 (P = .015). Somatic mutations in CTNNB1 were found in 50% of tumors from patients with pathogenic variants in MLH1 vs 7% in MSH2 (P = .002). None of the 3 tumors with pathogenic variants in MSH6 had a mutation in CTNNB1, but all had mutations in APC.

Conclusions: In an analysis of clinical and DNA sequence data from patients with Lynch syndrome from 3 countries, we associated pathogenic variants in MMR genes with risk of adenoma and CRC, and somatic mutations in APC and CTNNB1 in colorectal tumors. If these findings are confirmed, surveillance guidelines might be adjusted based on MMR gene variants.
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http://dx.doi.org/10.1053/j.gastro.2019.12.032DOI Listing
April 2020

Cancer risks by gene, age, and gender in 6350 carriers of pathogenic mismatch repair variants: findings from the Prospective Lynch Syndrome Database.

Genet Med 2020 01 24;22(1):15-25. Epub 2019 Jul 24.

Hereditary Cancer Program (PROCANHE), Hospital Italiano de Buenos Aires, Buenos Aires, Argentina.

Purpose: Pathogenic variants affecting MLH1, MSH2, MSH6, and PMS2 cause Lynch syndrome and result in different but imprecisely known cancer risks. This study aimed to provide age and organ-specific cancer risks according to gene and gender and to determine survival after cancer.

Methods: We conducted an international, multicenter prospective observational study using independent test and validation cohorts of carriers of class 4 or class 5 variants. After validation the cohorts were merged providing 6350 participants and 51,646 follow-up years.

Results: There were 1808 prospectively observed cancers. Pathogenic MLH1 and MSH2 variants caused high penetrance dominant cancer syndromes sharing similar colorectal, endometrial, and ovarian cancer risks, but older MSH2 carriers had higher risk of cancers of the upper urinary tract, upper gastrointestinal tract, brain, and particularly prostate. Pathogenic MSH6 variants caused a sex-limited trait with high endometrial cancer risk but only modestly increased colorectal cancer risk in both genders. We did not demonstrate a significantly increased cancer risk in carriers of pathogenic PMS2 variants. Ten-year crude survival was over 80% following colon, endometrial, or ovarian cancer.

Conclusion: Management guidelines for Lynch syndrome may require revision in light of these different gene and gender-specific risks and the good prognosis for the most commonly associated cancers.
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http://dx.doi.org/10.1038/s41436-019-0596-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7371626PMC
January 2020

Lack of association between screening interval and cancer stage in Lynch syndrome may be accounted for by over-diagnosis; a prospective Lynch syndrome database report.

Hered Cancer Clin Pract 2019 28;17. Epub 2019 Feb 28.

28Department of Gastroenterology and Hepatology, Leiden University Medical Centre, Leiden, The Netherlands.

Background: Recent epidemiological evidence shows that colorectal cancer (CRC) continues to occur in carriers of pathogenic mismatch repair () variants despite frequent colonoscopy surveillance in expert centres. This observation conflicts with the paradigm that removal of all visible polyps should prevent the vast majority of CRC in carriers, provided the screening interval is sufficiently short and colonoscopic practice is optimal.

Methods: To inform the debate, we examined, in the Prospective Lynch Syndrome Database (PLSD), whether the time since last colonoscopy was associated with the pathological stage at which CRC was diagnosed during prospective surveillance. carriers were recruited for prospective surveillance by colonoscopy. Only variants scored by the InSiGHT Variant Interpretation Committee as class 4 and 5 (clinically actionable) were included. CRCs detected at the first planned colonoscopy, or within one year of this, were excluded as prevalent cancers.

Results: Stage at diagnosis and interval between last prospective surveillance colonoscopy and diagnosis were available for 209 patients with 218 CRCs, including 162 , 45 _, 10 and 1 carriers. The numbers of cancers detected within < 1.5, 1.5-2.5, 2.5-3.5 and at > 3.5 years since last colonoscopy were 36, 93, 56 and 33, respectively. Among these, 16.7, 19.4, 9.9 and 15.1% were stage III-IV, respectively ( = 0.34). The cancers detected more than 2.5 years after the last colonoscopy were not more advanced than those diagnosed earlier ( = 0.14).

Conclusions: The CRC stage and interval since last colonoscopy were not correlated, which is in conflict with the accelerated adenoma-carcinoma paradigm. We have previously reported that more frequent colonoscopy is not associated with lower incidence of CRC in carriers as was expected. In contrast, point estimates showed a higher incidence with shorter intervals between examinations, a situation that may parallel to over-diagnosis in breast cancer screening. Our findings raise the possibility that some CRCs in carriers may spontaneously disappear: the host immune response may not only remove CRC precursor lesions in carriers, but may remove infiltrating cancers as well. If confirmed, our suggested interpretation will have a bearing on surveillance policy for carriers.
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http://dx.doi.org/10.1186/s13053-019-0106-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6394091PMC
February 2019

Diagnostic yield and clinical utility of a comprehensive gene panel for hereditary tumor syndromes.

Hered Cancer Clin Pract 2019 23;17. Epub 2019 Jan 23.

1Institute of Human Genetics, University of Bonn, Sigmund-Freud-Str. 25, D-53127 Bonn, Germany.

Background: In a considerable number of patients with a suspected hereditary tumor syndrome (HTS), no underlying germline mutation is detected in the most likely affected genes. The present study aimed to establish and validate a large gene panel for HTS, and determine its diagnostic yield and clinical utility.

Methods: The study cohort comprised 173 patients with suspected, but unexplained, HTS (group U) and 64 HTS patients with a broad spectrum of known germline mutations (group K). All patients in group U presented with early age at onset, multiple tumors, and/or a familial clustering of various tumor types; no germline mutation had been identified during routine diagnostics. Sequencing of leukocyte DNA was performed for the 94 HTS genes of the Illumina TruSight™Cancer Panel and 54 additional HTS genes.

Results: The sensitivity of the panel to identify known germline variants was 99.6%. In addition to known mutations, a total of 192 rare, potentially pathogenic germline variants in 86 genes were identified. Neither the proportion of rare variants per patient (group K: 0.9 variants; group U: 0.8 variants) nor the proportion of variants in the most frequently mutated, moderately penetrant genes and showed significant inter-group difference. Four of the five patients from group U with a truncating mutation had thyroid cancer, pointing to a broader tumor spectrum in patients with pathogenic variants. In 22% of patients from group K, a further potential causative variant was identified. Here, the most interesting finding was an nonsense mutation in a child with a known frameshift mutation In 17% of patients from group U, potential causative variants were identified. In three of these patients (2%), mutations in , or were considered to be causative. In both groups, incidental findings with presumptive predictive value were generated.

Conclusions: The gene panel identified the genetic cause in some prescreened, unexplained HTS patients and generated incidental findings. Some patients harbored predicted pathogenic mutations in more than one established HTS gene, rendering interpretation of the respective alterations challenging. Established moderate risk genes showed an almost equal distribution among patients with known and unexplained disease.
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http://dx.doi.org/10.1186/s13053-018-0102-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6343270PMC
January 2019

No Difference in Colorectal Cancer Incidence or Stage at Detection by Colonoscopy Among 3 Countries With Different Lynch Syndrome Surveillance Policies.

Gastroenterology 2018 11 29;155(5):1400-1409.e2. Epub 2018 Jul 29.

Medizinische Klinik und Poliklinik IV, Campus Innenstadt, Klinikum der Universität München, Munich, Germany; Center of Medical Genetics, Munich, Germany.

Background & Aims: Patients with Lynch syndrome are at high risk for developing colorectal cancer (CRC). Regular colonoscopic surveillance is recommended, but there is no international consensus on the appropriate interval. We investigated whether shorter intervals are associated with lower CRC incidence and detection at earlier stages by comparing the surveillance policies in Germany, which evaluates patients by colonoscopy annually, in the Netherlands (patients evaluated at 1-2-year intervals), and Finland (patients evaluated at 2-3-year intervals).

Methods: We collected data from 16,327 colonoscopic examinations (conducted from 1984 through 2015) of 2747 patients with Lynch syndrome (pathogenic variants in the MLH1, MSH2, or MSH6 genes) from the German HNPCC Consortium, the Dutch Lynch Syndrome Registry, and the Finnish Lynch Syndrome Registry. Our analysis included 23,309 person-years of cumulative observation time. Time from the index colonoscopy to incident CRC or adenoma was analyzed using the Kaplan-Meier method; groups were compared using the log-rank test. We performed multivariable Cox regression analyses to identify factors associated with CRC risk (diagnosis of CRC before the index colonoscopy, sex, mutation, age, and presence of adenoma at the index colonoscopy).

Results: The 10-year cumulative CRC incidence ranged from 4.1% to 18.4% in patients with low- and high-risk profiles, respectively, and varied with age, sex, mutation, and prior detection of CRC or adenoma. Observed colonoscopy intervals were largely in accordance with the country-specific recommendations. We found no significant differences in cumulative CRC incidence or CRC stage at detection among countries. There was no significant association between CRC stage and time since last colonoscopy.

Conclusions: We did not find a significant reduction in CRC incidence or stage of detection in Germany (annual colonoscopic surveillance) than in countries with longer surveillance intervals (the Netherlands, with 1-2-year intervals, and Finland, with 2-3-year intervals). Overall, we did not find a significant association of the interval with CRC risk, although age, sex, mutation, and prior neoplasia were used to individually modify colonoscopy intervals. Studies are needed to develop and validate risk-adapted surveillance strategies and to identify patients who benefit from shorter surveillance intervals.
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http://dx.doi.org/10.1053/j.gastro.2018.07.030DOI Listing
November 2018

Copy number variation analysis and targeted NGS in 77 families with suspected Lynch syndrome reveals novel potential causative genes.

Int J Cancer 2018 12 3;143(11):2800-2813. Epub 2018 Oct 3.

Institute of Human Genetics, University of Bonn, Bonn, Germany.

In many families with suspected Lynch syndrome (LS), no germline mutation in the causative mismatch repair (MMR) genes is detected during routine diagnostics. To identify novel causative genes for LS, the present study investigated 77 unrelated, mutation-negative patients with clinically suspected LS and a loss of MSH2 in tumor tissue. An analysis for genomic copy number variants (CNV) was performed, with subsequent next generation sequencing (NGS) of selected candidate genes in a subgroup of the cohort. Genomic DNA was genotyped using Illumina's HumanOmniExpress Bead Array. After quality control and filtering, 25 deletions and 16 duplications encompassing 73 genes were identified in 28 patients. No recurrent CNV was detected, and none of the CNVs affected the regulatory regions of MSH2. A total of 49 candidate genes from genomic regions implicated by the present CNV analysis and 30 known or assumed risk genes for colorectal cancer (CRC) were then sequenced in a subset of 38 patients using a customized NGS gene panel and Sanger sequencing. Single nucleotide variants were identified in 14 candidate genes from the CNV analysis. The most promising of these candidate genes were: (i) PRKCA, PRKDC, and MCM4, as a functional relation to MSH2 is predicted by network analysis, and (ii) CSMD1, as this is commonly mutated in CRC. Furthermore, six patients harbored POLE variants outside the exonuclease domain, suggesting that these might be implicated in hereditary CRC. Analyses in larger cohorts of suspected LS patients recruited via international collaborations are warranted to verify the present findings.
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http://dx.doi.org/10.1002/ijc.31725DOI Listing
December 2018

Genomic and transcriptomic heterogeneity of colorectal tumours arising in Lynch syndrome.

J Pathol 2017 10 5;243(2):242-254. Epub 2017 Sep 5.

Institute of Pathology, Centre for Integrated Oncology, University Hospital Cologne, Cologne, Germany.

Colorectal cancer (CRC) arising in Lynch syndrome (LS) comprises tumours with constitutional mutations in DNA mismatch repair genes. There is still a lack of whole-genome and transcriptome studies of LS-CRC to address questions about similarities and differences in mutation and gene expression characteristics between LS-CRC and sporadic CRC, about the molecular heterogeneity of LS-CRC, and about specific mechanisms of LS-CRC genesis linked to dysfunctional mismatch repair in LS colonic mucosa and the possible role of immune editing. Here, we provide a first molecular characterization of LS tumours and of matched tumour-distant reference colonic mucosa based on whole-genome DNA-sequencing and RNA-sequencing analyses. Our data support two subgroups of LS-CRCs, G1 and G2, whereby G1 tumours show a higher number of somatic mutations, a higher amount of microsatellite slippage, and a different mutation spectrum. The gene expression phenotypes support this difference. Reference mucosa of G1 shows a strong immune response associated with the expression of HLA and immune checkpoint genes and the invasion of CD4+ T cells. Such an immune response is not observed in LS tumours, G2 reference and normal (non-Lynch) mucosa, and sporadic CRC. We hypothesize that G1 tumours are edited for escape from a highly immunogenic microenvironment via loss of HLA presentation and T-cell exhaustion. In contrast, G2 tumours seem to develop in a less immunogenic microenvironment where tumour-promoting inflammation parallels tumourigenesis. Larger studies on non-neoplastic mucosa tissue of mutation carriers are required to better understand the early phases of emerging tumours. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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http://dx.doi.org/10.1002/path.4948DOI Listing
October 2017

Prophylactic total gastrectomy in the management of hereditary tumor syndromes.

Int J Colorectal Dis 2016 Dec 28;31(12):1825-1833. Epub 2016 Sep 28.

Department of General, Visceral, Thoracic and Vascular Surgery, University Hospital of Bonn, Bonn, Germany.

Purpose: Germline mutations in several genes confer a relevant lifetime risk of gastric cancer. In this context, an increasing involvement of a surgeon can be seen, mainly with the question of performing a prophylactic operation.

Methods: Patients with hereditary tumor syndromes predisposing for gastric cancer who received care leading to prophylactic total gastrectomy in our Center for Hereditary Tumor Syndromes were analyzed. For each patient, the multidisciplinary decision-making process, the perioperative course, and the histopathologic findings were assessed. Short-term morbidity was evaluated based on the medical reports.

Results: The analysis includes nine patients (six female, three male) with a median age of 41.6 (range 23-60) years. Indication for prophylactic total gastrectomy was based on family history and genetic analysis (eight patients with a germline mutation of the CDH1 gene and one patient with a SMAD4 mutation). Removal of the entire gastric mucosa was documented intraoperatively by fresh frozen section examination. Extended (DII) lymphadenectomy was performed in four patients. Histopathologic examination of gastrectomy specimens revealed six patients (6/9, 67 %) with multifocal signet ring cell carcinomas. In our series, prophylactic total gastrectomy was a safe procedure without mortality and low morbidity.

Conclusions: Patients with hereditary syndromes predisposing for gastric cancer should be evaluated for this curative procedure in a specialized center. Further research is necessary, and the implementation of nationwide registers including patients with prophylactic gastrointestinal operations due to hereditary tumor syndrome is advisable.
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http://dx.doi.org/10.1007/s00384-016-2656-9DOI Listing
December 2016

Exome Sequencing Identifies Biallelic MSH3 Germline Mutations as a Recessive Subtype of Colorectal Adenomatous Polyposis.

Am J Hum Genet 2016 Aug 28;99(2):337-51. Epub 2016 Jul 28.

Institute of Human Genetics, University of Bonn, 53127 Bonn, Germany; Center for Hereditary Tumor Syndromes, University of Bonn, 53127 Bonn, Germany. Electronic address:

In ∼30% of families affected by colorectal adenomatous polyposis, no germline mutations have been identified in the previously implicated genes APC, MUTYH, POLE, POLD1, and NTHL1, although a hereditary etiology is likely. To uncover further genes with high-penetrance causative mutations, we performed exome sequencing of leukocyte DNA from 102 unrelated individuals with unexplained adenomatous polyposis. We identified two unrelated individuals with differing compound-heterozygous loss-of-function (LoF) germline mutations in the mismatch-repair gene MSH3. The impact of the MSH3 mutations (c.1148delA, c.2319-1G>A, c.2760delC, and c.3001-2A>C) was indicated at the RNA and protein levels. Analysis of the diseased individuals' tumor tissue demonstrated high microsatellite instability of di- and tetranucleotides (EMAST), and immunohistochemical staining illustrated a complete loss of nuclear MSH3 in normal and tumor tissue, confirming the LoF effect and causal relevance of the mutations. The pedigrees, genotypes, and frequency of MSH3 mutations in the general population are consistent with an autosomal-recessive mode of inheritance. Both index persons have an affected sibling carrying the same mutations. The tumor spectrum in these four persons comprised colorectal and duodenal adenomas, colorectal cancer, gastric cancer, and an early-onset astrocytoma. Additionally, we detected one unrelated individual with biallelic PMS2 germline mutations, representing constitutional mismatch-repair deficiency. Potentially causative variants in 14 more candidate genes identified in 26 other individuals require further workup. In the present study, we identified biallelic germline MSH3 mutations in individuals with a suspected hereditary tumor syndrome. Our data suggest that MSH3 mutations represent an additional recessive subtype of colorectal adenomatous polyposis.
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http://dx.doi.org/10.1016/j.ajhg.2016.06.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4974087PMC
August 2016

Exome sequencing identifies potential novel candidate genes in patients with unexplained colorectal adenomatous polyposis.

Fam Cancer 2016 Apr;15(2):281-8

Institute of Human Genetics, University of Bonn, Sigmund-Freud-Str. 25, 53127, Bonn, Germany.

In up to 30% of patients with colorectal adenomatous polyposis, no germline mutation in the known genes APC, causing familial adenomatous polyposis, MUTYH, causing MUTYH-associated polyposis, and POLE or POLD1, causing Polymerase-Proofreading-associated polyposis can be identified, although a hereditary etiology is likely. To uncover new causative genes, exome sequencing was performed using DNA from leukocytes and a total of 12 colorectal adenomas from seven unrelated patients with unexplained sporadic adenomatous polyposis. For data analysis and variant filtering, an established bioinformatics pipeline including in-house tools was applied. Variants were filtered for rare truncating point mutations and copy-number variants assuming a dominant, recessive, or tumor suppressor model of inheritance. Subsequently, targeted sequence analysis of the most promising candidate genes was performed in a validation cohort of 191 unrelated patients. All relevant variants were validated by Sanger sequencing. The analysis of exome sequencing data resulted in the identification of rare loss-of-function germline mutations in three promising candidate genes (DSC2, PIEZO1, ZSWIM7). In the validation cohort, further variants predicted to be pathogenic were identified in DSC2 and PIEZO1. According to the somatic mutation spectra, the adenomas in this patient cohort follow the classical pathways of colorectal tumorigenesis. The present study identified three candidate genes which might represent rare causes for a predisposition to colorectal adenoma formation. Especially PIEZO1 (FAM38A) and ZSWIM7 (SWS1) warrant further exploration. To evaluate the clinical relevance of these genes, investigation of larger patient cohorts and functional studies are required.
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http://dx.doi.org/10.1007/s10689-016-9870-zDOI Listing
April 2016

Low-level APC mutational mosaicism is the underlying cause in a substantial fraction of unexplained colorectal adenomatous polyposis cases.

J Med Genet 2016 Mar 27;53(3):172-9. Epub 2015 Nov 27.

Institute of Human Genetics, University of Bonn, Bonn, Germany Center for Hereditary Tumor Syndromes, University of Bonn, Bonn, Germany.

Background: In 30-50% of patients with colorectal adenomatous polyposis, no germline mutation in the known genes APC, causing familial adenomatous polyposis, MUTYH, causing MUTYH-associated polyposis, or POLE or POLD1, causing polymerase-proofreading-associated polyposis can be identified, although a hereditary aetiology is likely. This study aimed to explore the impact of APC mutational mosaicism in unexplained polyposis.

Methods: To comprehensively screen for somatic low-level APC mosaicism, high-coverage next-generation sequencing of the APC gene was performed using DNA from leucocytes and a total of 53 colorectal tumours from 20 unrelated patients with unexplained sporadic adenomatous polyposis. APC mosaicism was assumed if the same loss-of-function APC mutation was present in ≥ 2 anatomically separated colorectal adenomas/carcinomas per patient. All mutations were validated using diverse methods.

Results: In 25% (5/20) of patients, somatic mosaicism of a pathogenic APC mutation was identified as underlying cause of the disease. In 2/5 cases, the mosaic level in leucocyte DNA was slightly below the sensitivity threshold of Sanger sequencing; while in 3/5 cases, the allelic fraction was either very low (0.1-1%) or no mutations were detectable. The majority of mosaic mutations were located outside the somatic mutation cluster region of the gene.

Conclusions: The present data indicate a high prevalence of pathogenic mosaic APC mutations below the detection thresholds of routine diagnostics in adenomatous polyposis, even if high-coverage sequencing of leucocyte DNA alone is taken into account. This has important implications for both routine work-up and strategies to identify new causative genes in this patient group.
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http://dx.doi.org/10.1136/jmedgenet-2015-103468DOI Listing
March 2016

Activating ERBB2/HER2 mutations indicate susceptibility to pan-HER inhibitors in Lynch and Lynch-like colorectal cancer.

Gut 2016 08 28;65(8):1296-305. Epub 2015 Apr 28.

Institute of Pathology, Centre for Integrated Oncology, University Hospital Cologne, Cologne, Germany.

Objective: Microsatellite instability (MSI) is detected in approximately 15% of all colorectal cancers (CRC) and virtually in all cases with Lynch syndrome. The MSI phenotype is caused by dysfunctional mismatch repair (MMR) and leads to accumulation of DNA replication errors. Sporadic MSI CRC often harbours BRAF(V600E); however, no consistent data exist regarding targeted treatment approaches in BRAF(wt) MSI CRC.

Design: Mutations and quantitative MSI were analysed by deep sequencing in 196 formalin fixed paraffin embedded (FFPE) specimens comprising Lynch and Lynch-like CRCs from the German Hereditary Nonpolyposis Colorectal Cancer registry. Functional relevance of recurrent ERBB2/HER2 mutations was investigated in CRC cell lines using reversible and irreversible HER-targeting inhibitors, EGFR-directed antibody cetuximab, HER2-directed antibody trastuzumab and siRNA-mediated ERBB2/HER2 knockdown.

Results: Quantification of nucleotide loss in non-coding mononucleotide repeats distinguished microsatellite status with very high accuracy (area under curve=0.9998) and demonstrated progressive losses with deeper invasion of MMR-deficient colorectal neoplasms (p=0.008). Characterisation of BRAF(wt) MSI CRC revealed hot-spot mutations in well-known oncogenic drivers, including KRAS (38.7%), PIK3CA (36.5%), and ERBB2 (15.0%). L755S and V842I substitutions in ERBB2 were highly recurrent. Functional analyses in ERBB2-mutated MSI CRC cell lines revealed a differential response to HER-targeting compounds and superiority of irreversible pan-HER inhibitors.

Conclusions: We developed a high-throughput deep sequencing approach for concomitant MSI and mutational analyses in FFPE specimens. We provided novel insights into clinically relevant alterations in MSI CRC and a rationale for targeting ERBB2/HER2 mutations in Lynch and Lynch-like CRC.
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http://dx.doi.org/10.1136/gutjnl-2014-309026DOI Listing
August 2016

Frequency and phenotypic spectrum of germline mutations in POLE and seven other polymerase genes in 266 patients with colorectal adenomas and carcinomas.

Int J Cancer 2015 Jul 20;137(2):320-31. Epub 2015 Jan 20.

Institute of Human Genetics, University of Bonn, Bonn, Germany.

In a number of families with colorectal adenomatous polyposis or suspected Lynch syndrome/HNPCC, no germline alteration in the APC, MUTYH, or mismatch repair (MMR) genes are found. Missense mutations in the polymerase genes POLE and POLD1 have recently been identified as rare cause of multiple colorectal adenomas and carcinomas, a condition termed polymerase proofreading-associated polyposis (PPAP). The aim of the present study was to evaluate the clinical relevance and phenotypic spectrum of polymerase germline mutations. Therefore, targeted sequencing of the polymerase genes POLD1, POLD2, POLD3, POLD4, POLE, POLE2, POLE3 and POLE4 was performed in 266 unrelated patients with polyposis or fulfilled Amsterdam criteria. The POLE mutation c.1270C>G;p.Leu424Val was detected in four unrelated patients. The mutation was present in 1.5% (4/266) of all patients, 4% (3/77) of all familial cases and 7% (2/30) of familial polyposis cases. The colorectal phenotype in 14 affected individuals ranged from typical adenomatous polyposis to a HNPCC phenotype, with high intrafamilial variability. Multiple colorectal carcinomas and duodenal adenomas were common, and one case of duodenal carcinoma was reported. Additionally, various extraintestinal lesions were evident. Nine further putative pathogenic variants were identified. The most promising was c.1306C>T;p.Pro436Ser in POLE. In conclusion, a PPAP was identified in a substantial number of polyposis and familial colorectal cancer patients. Screening for polymerase proofreading mutations should therefore be considered, particularly in unexplained familial cases. The present study broadens the phenotypic spectrum of PPAP to duodenal adenomas and carcinomas, and identified novel, potentially pathogenic variants in four polymerase genes.
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http://dx.doi.org/10.1002/ijc.29396DOI Listing
July 2015

Functional testing strategy for coding genetic variants of unclear significance in MLH1 in Lynch syndrome diagnosis.

Carcinogenesis 2015 Feb 4;36(2):202-11. Epub 2014 Dec 4.

Biomedical Research Laboratory, Department of Internal Medicine 1 and Department of Human Genetics, Universitätsklinikum Frankfurt, Frankfurt D-60590, Germany, Institute of Human Genetics, University of Bonn, Bonn D-53127, Germany and Department of Internal Medicine 1, Universitätsklinikum Frankfurt D-60590, Frankfurt, Germany

Lynch syndrome is caused by inactivating mutations in the MLH1 gene, but genetic variants of unclear significance frequently preclude diagnosis. Functional testing can reveal variant-conferred defects in gene or protein function. Based on functional defect frequencies and clinical applicability of test systems, we developed a functional testing strategy aimed at efficiently detecting pathogenic defects in coding MLH1 variants. In this strategy, tests of repair activity and expression are prioritized over analyses of subcellular protein localization and messenger RNA (mRNA) formation. This strategy was used for four unclear coding MLH1 variants (p.Asp41His, p.Leu507Phe, p.Gln689Arg, p.Glu605del + p.Val716Met). Expression was analyzed using a transfection system, mismatch repair (MMR) activity by complementation in vitro, mRNA formation by reverse transcriptase-PCR in carrier lymphocyte mRNA, and subcellular localization with dye-labeled fusion constructs. All tests included clinically meaningful controls. The strategy enabled efficient identification of defects in two unclear variants: the p.Asp41His variant showed loss of MMR activity, whereas the compound variant p.Glu605del + p.Val716Met had a defect of expression. This expression defect was significantly stronger than the pathogenic expression reference variant analyzed in parallel, therefore the defect of the compound variant is also pathogenic. Interestingly, the expression defect was caused additively by both of the compound variants, at least one of which is non-pathogenic when occurring by itself. Tests were neutral for p.Leu507Phe and p.Gln689Arg, and the results were consistent with available clinical data. We finally discuss the improved sensitivity and efficiency of the applied strategy and its limitations in analyzing unclear coding MLH1 variants.
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http://dx.doi.org/10.1093/carcin/bgu239DOI Listing
February 2015

Germline variants in the SEMA4A gene predispose to familial colorectal cancer type X.

Nat Commun 2014 Oct 13;5:5191. Epub 2014 Oct 13.

Division of Hematology, Department of Internal Medicine, Medical University of Graz, A-8036 Graz, Austria.

Familial colorectal cancer type X (FCCTX) is characterized by clinical features of hereditary non-polyposis colorectal cancer with a yet undefined genetic background. Here we identify the SEMA4A p.Val78Met germline mutation in an Austrian kindred with FCCTX, using an integrative genomics strategy. Compared with wild-type protein, SEMA4A(V78M) demonstrates significantly increased MAPK/Erk and PI3K/Akt signalling as well as cell cycle progression of SEMA4A-deficient HCT-116 colorectal cancer cells. In a cohort of 53 patients with FCCTX, we depict two further SEMA4A mutations, p.Gly484Ala and p.Ser326Phe and the single-nucleotide polymorphism (SNP) p.Pro682Ser. This SNP is highly associated with the FCCTX phenotype exhibiting increased risk for colorectal cancer (OR 6.79, 95% CI 2.63 to 17.52). Our study shows previously unidentified germline variants in SEMA4A predisposing to FCCTX, which has implications for surveillance strategies of patients and their families.
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http://dx.doi.org/10.1038/ncomms6191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4214414PMC
October 2014

Genome-wide CNV analysis in 221 unrelated patients and targeted high-throughput sequencing reveal novel causative candidate genes for colorectal adenomatous polyposis.

Int J Cancer 2015 Mar 30;136(6):E578-89. Epub 2014 Sep 30.

Institute of Human Genetics, University of Bonn, Bonn, Germany.

To uncover novel causative genes in patients with unexplained adenomatous polyposis, a model disease for colorectal cancer, we performed a genome-wide analysis of germline copy number variants (CNV) in a large, well characterized APC and MUTYH mutation negative patient cohort followed by a targeted next generation sequencing (NGS) approach. Genomic DNA from 221 unrelated German patients was genotyped on high-resolution SNP arrays. Putative CNVs were filtered according to stringent criteria, compared with those of 531 population-based German controls, and validated by qPCR. Candidate genes were prioritized using in silico, expression, and segregation analyses, data mining and enrichment analyses of genes and pathways. In 27% of the 221 unrelated patients, a total of 77 protein coding genes displayed rare, nonrecurrent, germline CNVs. The set included 26 candidates with molecular and cellular functions related to tumorigenesis. Targeted high-throughput sequencing found truncating point mutations in 12% (10/77) of the prioritized genes. No clear evidence was found for autosomal recessive subtypes. Six patients had potentially causative mutations in more than one of the 26 genes. Combined with data from recent studies of early-onset colorectal and breast cancer, recurrent potential loss-of-function alterations were detected in CNTN6, FOCAD (KIAA1797), HSPH1, KIF26B, MCM3AP, YBEY and in three genes from the ARHGAP family. In the canonical Wnt pathway oncogene CTNNB1 (β-catenin), two potential gain-of-function mutations were found. In conclusion, the present study identified a group of rarely affected genes which are likely to predispose to colorectal adenoma formation and confirmed previously published candidates for tumor predisposition as etiologically relevant.
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http://dx.doi.org/10.1002/ijc.29215DOI Listing
March 2015

Evaluating the performance of clinical criteria for predicting mismatch repair gene mutations in Lynch syndrome: a comprehensive analysis of 3,671 families.

Int J Cancer 2014 Jul 20;135(1):69-77. Epub 2014 Feb 20.

Institute of Human Genetics, University of Bonn, Bonn, Germany.

Carriers of mismatch repair (MMR) gene mutations have a high lifetime risk for colorectal and endometrial cancers, as well as other malignancies. As mutation analysis to detect these patients is expensive and time-consuming, clinical criteria and tumor-tissue analysis are widely used as pre-screening methods. The aim of our study was to evaluate the performance of commonly applied clinical criteria (the Amsterdam I and II Criteria, and the original and revised Bethesda Guidelines) and the results of tumor-tissue analysis in predicting MMR gene mutations. We analyzed 3,671 families from the German HNPCC Registry and divided them into nine mutually exclusive groups with different clinical criteria. A total of 680 families (18.5%) were found to have a pathogenic MMR gene mutation. Among all 1,284 families with microsatellite instability-high (MSI-H) colorectal cancer, the overall mutation detection rate was 53.0%. Mutation frequencies and their distribution between the four MMR genes differed significantly between clinical groups (p < 0.001). The highest frequencies were found in families fulfilling the Amsterdam Criteria (46.4%). Families with loss of MSH2 expression had higher mutation detection rates (69.5%) than families with loss of MLH1 expression (43.1%). MMR mutations were found significantly more often in families with at least one MSI-H small-bowel cancer (p < 0.001). No MMR mutations were found among patients under 40-years-old with only colorectal adenoma. Familial clustering of Lynch syndrome-related tumors, early age of onset, and familial occurrence of small-bowel cancer were clinically relevant predictors for Lynch syndrome.
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http://dx.doi.org/10.1002/ijc.28650DOI Listing
July 2014

Decreased levels of histone H3K9me1 indicate poor prognosis in patients with renal cell carcinoma.

Anticancer Res 2012 Mar;32(3):879-86

Department of Urology, University Hospital Bonn, Bonn, Germany.

Background/aim: To determine the role of global histone H3K9 and H4K20 methylation levels as prognostic parameters in patients with renal cell cancer (RCC).

Material And Methods: Global histone methylation levels were investigated in 193 RCC (including 142 clear cell (cc), 31 papillary (p), 10 chromophobe (ch) and 10 sarcomatoid (s) RCC), 10 oncocytomas and 30 benign renal specimens.

Results: Histone modifications were mostly similar in the different histological subtypes (p>0.05); significant differences were observed for ccRCC vs. pRCC and pRCC vs. sRCC. Comparing the global H3K9 methylation levels of benign renal tissue with RCC H3K9me1 (histone H3 lysine 9 mono-methylation) (p<0.001), H3K9me2 (histone H3 lysine 9 di-methylation) (p=0.001) and H3K9me3 (histone H3 lysine 9 tri-methylation) (p<0.001) was significantly over-expressed in benign renal tissue. H3K9 and H4K20 methylation levels were positively correlated to pT-stage (p<0.005) and grading (p<0.05). In localized RCC (n=144), H3K9me1 levels showed a significant correlation with progression-free survival in the univariate model (p=0.034).

Conclusion: Global histone methylation levels may help to identify RCC patients with poor prognosis.
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March 2012

Global histone acetylation levels: prognostic relevance in patients with renal cell carcinoma.

Cancer Sci 2010 Dec 1;101(12):2664-9. Epub 2010 Sep 1.

Department of Urology, University Hospital Bonn, Bonn, Germany.

Epigenetic alterations play an important role in carcinogenesis. Recent studies have suggested that global histone modifications are predictors of cancer recurrence in various tumor entities. Global histone acetylation levels (histone H3 lysine 9 acetylation [H3K9Ac], histone H3 lysine 18 acetylation [H3K18Ac], total histone H3 acetylation [H3Ac] and total histone H4 acetylation [H4Ac]) were determined in patients with renal cell carcinoma (RCC) using immunohistochemistry in a tissue micro array with 193 RCC and 10 oncocytoma specimens. The histone acetylation pattern was not different among the diverse histological subtypes of RCC or oncocytoma samples. The H3Ac levels were inversely correlated with pT-stage (P = 0.005), distant metastasis (P = 0.036), Fuhrman grading (P = 0.001) and RCC progression (P = 0.029, hazard ratio 0.87). H4Ac deacetylation was correlated with pT-stage (P = 0.011) and grading (P = 0.029). H3K18Ac levels were an independent predictor of cancer-progression following surgery for localized RCC in the univariate (P = 0.001, hazard ratio 0.78) and multivariate (P = 0.005, hazard ratio 0.82) analysis. In conclusion, our study supports the concept of global histone modification levels as a universal cancer prognosis marker, and provides evidence for the use of histone deacetylases inhibitors as future drugs in the therapy of RCC.
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http://dx.doi.org/10.1111/j.1349-7006.2010.01717.xDOI Listing
December 2010