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Background: This study investigates the potential influence of genotype and parent-of-origin effects (POE) on the clinical manifestations of Lynch syndrome (LS) within families carrying (likely) disease-causing MSH6 germline variants., Patients and Methods: A cohort of 1615 MSH6 variant carriers (310 LS families) was analyzed. Participants were categorized based on RNA expression and parental inheritance of the variant. Hazard ratios (HRs) were calculated using weighted Cox regression, considering external information to address ascertainment bias. The findings were cross-validated using the Prospective Lynch Syndrome Database (PLSD) for endometrial cancer (EC)., Results: No significant association was observed between genotype and colorectal cancer (CRC) risk (HR = 1.06, 95% confidence interval [CI]: 0.77-1.46). Patients lacking expected RNA expression exhibited a reduced risk of EC (Reference Cohort 1: HR = 0.68, 95% CI: 0.43-1.03; Reference Cohort 2: HR = 0.63, 95% CI: 0.46-0.87). However, these results could not be confirmed in the PLSD. Moreover, no association was found between POE and CRC risk (HR = 0.78, 95% CI: 0.52-1.17) or EC risk (Reference Cohort 1: HR = 0.93, 95% CI: 0.65-1.33; Reference Cohort 2: HR = 0.8, 95% CI: 0.64-1.19)., Discussion and Conclusion: No evidence of POE was detected in MSH6 families. While RNA expression may be linked to varying risks of EC, further investigation is required to explore this observation., (© 2024 The Authors. Genes, Chromosomes and Cancer published by Wiley Periodicals LLC.)

Screening for Lynch syndrome (LS) in colorectal cancer (CRC) and endometrial cancer patients generally involves immunohistochemical staining of the mismatch repair (MMR) proteins. In case of MLH1 protein loss, MLH1 promotor hypermethylation (MLH1-PM) testing is performed to indirectly distinguish the constitutional MLH1 variants from somatic epimutations. Recently, multiple studies have reported that MLH1-PM and pathogenic constitutional MMR variants are not mutually exclusive. This study describes 6 new and 86 previously reported MLH1-PM CRCs or endometrial cancers in LS patients. Of these, methylation of the MLH1 gene promotor C region was reported in 30 MLH1, 6 MSH2, 6 MSH6, and 3 PMS2 variant carriers at a median age at diagnosis of 48.5 years [interquartile range (IQR), 39-56.75 years], 39 years (IQR, 29-51 years), 58 years (IQR, 53.5-67 years), and 68 years (IQR, 65.6-68.5 years), respectively. For 31 MLH1-PM CRCs in LS patients from the literature, only the B region of the MLH1 gene promotor was tested, whereas for 13 cases in the literature the tested region was not specified. Collectively, these data indicate that a diagnosis of LS should not be excluded when MLH1-PM is detected. Clinicians should carefully consider whether follow-up genetic MMR gene testing should be offered, with age <60 to 70 years and/or a positive family history among other factors being suggestive for a potential constitutional MMR gene defect., Competing Interests: Disclosure Statement None declared., (Copyright © 2024 Association for Molecular Pathology and American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Diagnosis of Lynch syndrome (LS) caused by a pathogenic germline MSH6 variant may be complicated by discordant immunohistochemistry (IHC) and/or by a microsatellite stable (MSS) phenotype. This study aimed to identify the various causes of the discordant phenotypes of colorectal cancer (CRC) and endometrial cancer (EC) in MSH6-associated LS. Data were collected from Dutch family cancer clinics. Carriers of a (likely) pathogenic MSH6 variant diagnosed with CRC or EC were categorized based on an microsatellite instability (MSI)/IHC test outcome that might fail to result in a diagnosis of LS (eg, retained staining of all 4 mismatch repair proteins, with or without an MSS phenotype, and other staining patterns). When tumor tissue was available, MSI and/or IHC were repeated. Next-generation sequencing (NGS) was performed in cases with discordant staining patterns. Data were obtained from 360 families with 1763 (obligate) carriers. MSH6 variant carriers with CRC or EC (n = 590) were included, consisting of 418 CRCs and 232 ECs. Discordant staining was reported in 77 cases (36% of MSI/IHC results). Twelve patients gave informed consent for further analysis of tumor material. Upon revision, 2 out of 3 MSI/IHC cases were found to be concordant with the MSH6 variant, and NGS showed that 4 discordant IHC results were sporadic rather than LS-associated tumors. In 1 case, somatic events explained the discordant phenotype. The use of reflex IHC mismatch repair testing, the current standard in most Western countries, may lead to the misdiagnosis of germline MSH6 variant carriers. The pathologist should point out that further diagnostics for inheritable colon cancer, including LS, should be considered in case of a strong positive family history. Germline DNA analysis of the mismatch repair genes, preferably as part of a larger gene panel, should therefore be considered in potential LS patients., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: The Prospective Lynch Syndrome Database (PLSD) collates information on carriers of pathogenic or likely pathogenic MMR variants ( path&#95;MMR ) who are receiving medical follow-up, including colonoscopy surveillance, which aims to the achieve early diagnosis and treatment of cancers. Here we use the most recent PLSD cohort that is larger and has wider geographical representation than previous versions, allowing us to present mortality as an outcome, and median ages at cancer diagnoses for the first time., Methods: The PLSD is a prospective observational study without a control group that was designed in 2012 and updated up to October 2022. Data for 8500 carriers of path&#95;MMR variants from 25 countries were included, providing 71,713 years of follow up. Cumulative cancer incidences at 65 years of age were combined with 10-year crude survival following cancer, to derive estimates of mortality up to 75 years of age by organ, gene, and gender., Findings: Gynaecological cancers were more frequent than colorectal cancers in path&#95;MSH2, path&#95;MSH6 and path&#95;PMS2 carriers [cumulative incidence: 53.3%, 49.6% and 23.3% at 75 years, respectively]. Endometrial, colon and ovarian cancer had low mortality [8%, 13% and 15%, respectively] and prostate cancers were frequent in male path&#95;MSH2 carriers [cumulative incidence: 39.7% at 75 years]. Pancreatic, brain, biliary tract and ureter and kidney and urinary bladder cancers were associated with high mortality [83%, 66%, 58%, 27%, and 29%, respectively]. Among path&#95;MMR carriers undergoing colonoscopy surveillance, particularly path&#95;MSH2 carriers, more deaths followed non-colorectal Lynch syndrome cancers than colorectal cancers., Interpretation: In path&#95;MMR carriers undergoing colonoscopy surveillance, non-colorectal Lynch syndrome cancers were associated with more deaths than were colorectal cancers. Reducing deaths from non-colorectal cancers presents a key challenge in contemporary medical care in Lynch syndrome., Funding: We acknowledge funding from the Norwegian Cancer Society, contract 194751-2017., Competing Interests: R.B. has received honoraria for lectures and advisory boards from AbbVie, Amgen, AstraZeneca, Bayer, BMS, Boehringer-Ingelheim, Illumina, Lilly, Merck-Serono, MSD, Novartis, Qiagen, Pfizer, Roche, and Targos MP Inc. R.B. is a Co-Founder and Scientific Advisor for Targos Mol. Pathology Inc. Kassel/Germany. T.T.S. is the CEO and co-owner of Healthfund Finland Oy and reports consultation fees from Boehringer Ingelheim Finland and Amgen. FB is supported by JANSSEN PHARMACEUTICALS (clinical trial for Familial Adenomatous polyposis). RH is supported by the 10.13039/501100002424Fujifilm Germany and Janssen-Pharmaceuticals. LK is consultant of Sandoz, Novartis and Abbott. GM reports consultancy fees from Johnson & Johnson., (© 2023 The Author(s).)

Carriers of any pathogenic variant in one of the MMR genes ( path&#95;MMR carriers) were traditionally thought to be at comparable risk of developing a range of different malignancies, foremost colorectal cancer (CRC) and endometrial cancer. However, it is now widely accepted that their cancer risk and cancer spectrum range notably depending on which MMR gene is affected. Moreover, there is increasing evidence that the MMR gene affected also influences the molecular pathogenesis of Lynch syndrome CRC. Although substantial progress has been made over the past decade in understanding these differences, many questions remain unanswered, especially pertaining to path &#95; PMS2 carriers. Recent findings show that, while the cancer risk is relatively low, PMS2-deficient CRCs tend to show more aggressive behaviour and have a worse prognosis than other MMR-deficient CRCs. This, together with lower intratumoral immune infiltration, suggests that PMS2-deficient CRCs might have more in common biologically with sporadic MMR-proficient CRCs than with other MMR-deficient CRCs. These findings could have important consequences for surveillance, chemoprevention and therapeutic strategies (e.g. vaccines). In this review we discuss the current knowledge, current (clinical) challenges and knowledge gaps that should be targeted by future studies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Andini, Nielsen, Suerink, Helderman, Koornstra, Ahadova, Kloor, Mourits, Kok, Sijmons and Bajwa–ten Broeke.)

Objective: To compare colorectal cancer (CRC) incidences in carriers of pathogenic variants of the MMR genes in the PLSD and IMRC cohorts, of which only the former included mandatory colonoscopy surveillance for all participants., Methods: CRC incidences were calculated in an intervention group comprising a cohort of confirmed carriers of pathogenic or likely pathogenic variants in mismatch repair genes (path&#95;MMR) followed prospectively by the Prospective Lynch Syndrome Database (PLSD). All had colonoscopy surveillance, with polypectomy when polyps were identified. Comparison was made with a retrospective cohort reported by the International Mismatch Repair Consortium (IMRC). This comprised confirmed and inferred path&#95;MMR carriers who were first- or second-degree relatives of Lynch syndrome probands., Results: In the PLSD, 8,153 subjects had follow-up colonoscopy surveillance for a total of 67,604 years and 578 carriers had CRC diagnosed. Average cumulative incidences of CRC in path&#95;MLH1 carriers at 70 years of age were 52% in males and 41% in females; for path&#95;MSH2 50% and 39%; for path&#95;MSH6 13% and 17% and for path&#95;PMS2 11% and 8%. In contrast, in the IMRC cohort, corresponding cumulative incidences were 40% and 27%; 34% and 23%; 16% and 8% and 7% and 6%. Comparing just the European carriers in the two series gave similar findings. Numbers in the PLSD series did not allow comparisons of carriers from other continents separately. Cumulative incidences at 25 years were < 1% in all retrospective groups., Conclusions: Prospectively observed CRC incidences (PLSD) in path&#95;MLH1 and path&#95;MSH2 carriers undergoing colonoscopy surveillance and polypectomy were higher than in the retrospective (IMRC) series, and were not reduced in path&#95;MSH6 carriers. These findings were the opposite to those expected. CRC point incidence before 50 years of age was reduced in path&#95;PMS2 carriers subjected to colonoscopy, but not significantly so., (© 2022. The Author(s).)

Lynch syndrome (LS) is caused by a pathogenic heterozygous germline variant in one of the DNA mismatch repair (MMR) genes: MLH1, MSH2, MSH6 or PMS2. LS-associated colorectal carcinomas (CRCs) are characterized by MMR deficiency and by accumulation of multiple insertions/deletions at coding microsatellites (cMS). MMR deficiency-induced variants at defined cMS loci have a driver function and promote tumorigenesis. Notably, PMS2 variant carriers face only a slightly increased risk of developing CRC. Here, we investigate whether this lower penetrance is also reflected by differences in molecular features and cMS variant patterns. Tumor DNA was extracted from formalin-fixed paraffin-embedded (FFPE) tissue cores or sections (n = 90). Tumors originated from genetically proven germline pathogenic MMR variant carriers (including 14 PMS2-deficient tumors). The mutational spectrum was analyzed using fluorescently labeled primers specific for 18 cMS previously described as mutational targets in MMR-deficient tumors. Immune cell infiltration was analyzed by immunohistochemical detection of T-cells on FFPE tissue sections. The cMS spectrum of PMS2-deficient CRCs did not show any significant differences from MLH1/MSH2-deficient CRCs. PMS2-deficient tumors, however, displayed lower CD3-positive T-cell infiltration compared to other MMR-deficient cancers (28.00 vs. 55.00 per 0.1 mm 2 , p = 0.0025). Our study demonstrates that the spectrum of potentially immunogenic cMS variants in CRCs from PMS2 gene variant carriers is similar to that observed in CRCs from other MMR gene variant carriers. Lower immune cell infiltration observed in PMS2-deficient CRCs could be the result of alternative mechanisms of immune evasion or immune cell exclusion, similar to those seen in MMR-proficient tumors., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Lynch syndrome (LS) is a hereditary cancer syndrome that accounts for 3% of all new colorectal cancer (CRC) cases. Patients carry a germline pathogenic variant in one of the mismatch repair (MMR) genes (MLH1, MSH2, MSH6 or PMS2), which encode proteins involved in a post-replicative proofreading and editing mechanism. The clinical presentation of LS is highly heterogeneous, showing high variability in age at onset and penetrance of cancer, which may be partly attributable to the molecular profiles of carcinomas. This review discusses the frequency of alterations in the WNT/B-CATENIN, RAF/MEK/ERK and PI3K/PTEN/AKT pathways identified in all four LS subgroups and how these changes may relate to the 'three pathway model' of carcinogenesis, in which LS CRCs develop from MMR-proficient adenomas, MMR-deficient adenomas or directly from MMR-deficient crypts. Understanding the specific differences in carcinogenesis for each LS subgroup will aid in the further optimization of guidelines for diagnosis, surveillance and treatment., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

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&#95;MMR) variants., Methods: The Prospective Lynch Syndrome Database (PLSD) was used to investigate RRS by a cross-sectional study in 2292 female path&#95;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&#95;MLH1, path&#95;MSH2, path&#95;MSH6, and path&#95;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., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

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&#95;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&#95;MLH1, path&#95;MSH2, path&#95;MSH6, and path&#95;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&#95;MSH6 and path&#95;PMS2 heterozygotes has no measurable benefit for mortality. These findings may aid decision making for women with LS who are considering RRS.

Individuals with Lynch syndrome (LS), one of the most common inherited cancer syndromes, are at increased risk of developing malignancies, in particular colorectal cancer (CRC). Regular colonoscopy with polypectomy is recommended to reduce CRC risk in LS individuals. However, recent independent studies demonstrated that a substantial proportion of LS individuals develop CRC despite regular colonoscopy. The reasons for this surprising observation confirmed by large prospective studies are a matter of debate. In this review, we collect existing evidence from clinical, epidemiological and molecular studies and interpret them with regard to the origins and progression of LS-associated CRC. Alongside with hypotheses addressing colonoscopy quality and pace of progression from adenoma to cancer, we discuss the role of alternative precursors and immune system in LS-associated CRC. We also identify gaps in current knowledge and make suggestions for future studies aiming at improved CRC prevention for LS individuals., (© 2020 The Authors. International Journal of Cancer published by John Wiley & Sons Ltd on behalf of Union for International Cancer Control.)

This study aimed to determine the prevalence of APC-associated familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP) in a large cohort, taking into account factors as adenoma count and year of diagnosis. All application forms used to send patients in for APC and MUTYH variant analysis between 1992 and 2017 were collected (n = 2082). Using the data provided on the application form, the APC and biallelic MUTYH prevalence was determined and possible predictive factors were examined using multivariate multinomial logistic regression analysis in SPSS. The prevalence of disease causing variants in the APC gene significantly increases with adenoma count while MAP shows a peak prevalence in individuals with 50-99 adenomas. Logistic regression analysis shows significant odds ratios for adenoma count, age at diagnosis, and, interestingly, a decline in the chance of finding a variant in either gene over time. Moreover, in 22% (43/200) of patients with FAP-related extracolonic manifestations a variant was identified. The overall detection rates are above 10% for patients with >10 adenomas aged <60 and >20 adenomas aged <70. Patients with variants outside these criteria had FAP-related extracolonic manifestations, colorectal cancer aged <40, somatic KRAS c.34G > T variant in the tumor or a first-degree relative with >10 adenomas. Therefore, APC and MUTYH testing in patients with >10 adenomas aged <60 and with >20 adenomas aged <70 is advised. Almost all FAP and MAP patients not meeting these criteria showed other characteristics that can be used as an indication to prompt genetic testing.

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.

Purpose: Biallelic pathogenic variants in the mismatch repair (MMR) genes cause a recessive childhood cancer predisposition syndrome known as constitutional mismatch repair deficiency (CMMRD). Family members with a heterozygous MMR variant have Lynch syndrome. We aimed at estimating cancer risk in these heterozygous carriers as a novel approach to avoid complicated statistical methods to correct for ascertainment bias., Methods: Cumulative colorectal cancer incidence was estimated in a cohort of PMS2- and MSH6-associated families, ascertained by the CMMRD phenotype of the index, by using mutation probabilities based on kinship coefficients as analytical weights in a proportional hazard regression on the cause-specific hazards. Confidence intervals (CIs) were obtained by bootstrapping at the family level., Results: The estimated cumulative colorectal cancer risk at age 70 years for heterozygous PMS2 variant carriers was 8.7% (95% CI 4.3-12.7%) for both sexes combined, and 9.9% (95% CI 4.9-15.3%) for men and 5.9% (95% CI 1.6-11.1%) for women separately. For heterozygous MSH6 variant carriers these estimates are 11.8% (95% CI 4.5-22.7%) for both sexes combined, 10.0% (95% CI 1.83-24.5%) for men and 11.7% (95% CI 2.10-26.5%) for women., Conclusion: Our findings are consistent with previous reports that used more complex statistical methods to correct for ascertainment bias. These results underline the need for MMR gene-specific surveillance protocols for Lynch syndrome.

Background: We previously reported that in pathogenic mismatch repair ( path&#95;MMR ) variant carriers, the incidence of colorectal cancer (CRC) was not reduced when colonoscopy was undertaken more frequently than once every 3 years, and that CRC stage and interval since last colonoscopy were not correlated., Methods: The Prospective Lynch Syndrome Database (PLSD) that records outcomes of surveillance was examined to determine survival after colon cancer in relation to the time since previous colonoscopy and pathological stage. Only path&#95;MMR variants scored by the InSiGHT variant database as class 4 or 5 (clinically actionable) were included in the analysis., Results: Ninety-nine path&#95;MMR carriers had no cancer prior to or at first colonoscopy, but subsequently developed colon cancer. Among these, 96 were 65 years of age or younger at diagnosis, and included 77 path&#95;MLH1 , 17 path&#95;MSH2, and 2 path&#95;MSH6 carriers. The number of cancers detected within < 1.5, 1.5-2.5, 2.5-3.5 and at > 3.5 years after previous colonoscopy were 9, 43, 31 and 13, respectively. Of these, 2, 8, 4 and 3 were stage III, respectively, and only one stage IV (interval 2.5-3.5 years) disease. Ten-year crude survival after colon cancer were 93, 94 and 82% for stage I, II and III disease, respectively ( p  < 0.001). Ten-year crude survival when the last colonoscopy had been < 1.5, 1.5-2.5, 2.5-3.5 or > 3.5 years before diagnosis, was 89, 90, 90 and 92%, respectively ( p  = 0.91)., Conclusions: In path&#95;MLH1 and path&#95;MSH2 carriers, more advanced colon cancer stage was associated with poorer survival, whereas time since previous colonoscopy was not. Although the numbers are limited, together with our previously reported findings, these results may be in conflict with the view that follow-up of path&#95;MMR variant carriers with colonoscopy intervals of less than 3 years provides significant benefit., Competing Interests: Competing interestsToni Seppälä: a co-owner (20%) of Healthfund Finland Oy (educational and health care services in Finland, not related to patients or scope of this manuscript). Travel costs to a scientific meeting by Medtronic Finland. John Burn: a patent for high speed low cost tumor profiling pending to John Burn and QuantuMDx. All others: None declared., (© The Author(s). 2019.)

Background: PMS2-associated Lynch syndrome is characterized by a relatively low colorectal cancer penetrance compared with other Lynch syndromes. However, age at colorectal cancer diagnosis varies widely, and a strong genetic anticipation effect has been suggested for PMS2 families. In this study, we examined proposed genetic anticipation in a sample of 152 European PMS2 families., Methods: The 152 families (637 family members) that were eligible for analysis were mainly clinically ascertained via clinical genetics centers. We used weighted Cox-type random effects model, adjusted by birth cohort and sex, to estimate the generational effect on the age of onset of colorectal cancer. Probands and young birth cohorts were excluded from the analyses. Weights represented mutation probabilities based on kinship coefficients, thus avoiding testing bias., Results: Family data across three generations, including 123 colorectal cancers, were analyzed. When compared with the first generation, the crude HR for anticipation was 2.242 [95% confidence interval (CI), 1.162-4.328] for the second generation and 2.644 (95% CI, 1.082-6.464) for the third generation. However, after correction for birth cohort and sex, the effect vanished [HR = 1.302 (95% CI, 0.648-2.619) and HR = 1.074 (95% CI, 0.406-2.842) for second and third generations, respectively]., Conclusions: Our study did not confirm previous reports of genetic anticipation in PMS2-associated Lynch syndrome. Birth-cohort effect seems the most likely explanation for observed younger colorectal cancer diagnosis in subsequent generations, particularly because there is currently no commonly accepted biological mechanism that could explain genetic anticipation in Lynch syndrome., Impact: This new model for studying genetic anticipation provides a standard for rigorous analysis of families with dominantly inherited cancer predisposition., (©2019 American Association for Cancer Research.)

Biallelic germline mutations affecting NTHL1 predispose carriers to adenomatous polyposis and colorectal cancer, but the complete phenotype is unknown. We describe 29 individuals carrying biallelic germline NTHL1 mutations from 17 families, of which 26 developed one (n = 10) or multiple (n = 16) malignancies in 14 different tissues. An unexpected high breast cancer incidence was observed in female carriers (60%). Mutational signature analysis of 14 tumors from 7 organs revealed that NTHL1 deficiency underlies the main mutational process in all but one of the tumors (93%). These results reveal NTHL1 as a multi-tumor predisposition gene with a high lifetime risk for extracolonic cancers and a typical mutational signature observed across tumor types, which can assist in the recognition of this syndrome., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: Lynch syndrome due to pathogenic variants in the DNA mismatch repair genes MLH1, MSH2, and MSH6 is predominantly associated with colorectal and endometrial cancer, although extracolonic cancers have been described within the Lynch tumor spectrum. However, the age-specific cumulative risk (penetrance) of these cancers is still poorly defined for PMS2-associated Lynch syndrome. Using a large data set from a worldwide collaboration, our aim was to determine accurate penetrance measures of cancers for carriers of heterozygous pathogenic PMS2 variants., Methods: A modified segregation analysis was conducted that incorporated both genotyped and nongenotyped relatives, with conditioning for ascertainment to estimates corrected for bias. Hazard ratios (HRs) and corresponding 95% CIs were estimated for each cancer site for mutation carriers compared with the general population, followed by estimation of penetrance., Results: In total, 284 families consisting of 4,878 first- and second-degree family members were included in the analysis. PMS2 mutation carriers were at increased risk for colorectal cancer (cumulative risk to age 80 years of 13% [95% CI, 7.9% to 22%] for males and 12% [95% CI, 6.7% to 21%] for females) and endometrial cancer (13% [95% CI, 7.0%-24%]), compared with the general population (6.6%, 4.7%, and 2.4%, respectively). There was no clear evidence of an increased risk of ovarian, gastric, hepatobiliary, bladder, renal, brain, breast, prostate, or small bowel cancer., Conclusion: Heterozygous PMS2 mutation carriers were at small increased risk for colorectal and endometrial cancer but not for any other Lynch syndrome-associated cancer. This finding justifies that PMS2-specific screening protocols could be restricted to colonoscopies. The role of risk-reducing hysterectomy and bilateral salpingo-oophorectomy for PMS2 mutation carriers needs further discussion.

Lynch syndrome (LS) patients are at high risk of developing colorectal cancer (CRC). Phenotypic variability might in part be explained by common susceptibility loci identified in Genome Wide Association Studies (GWAS). Previous studies focused mostly on MLH1, MSH2 and MSH6 carriers, with conflicting results. We aimed to determine the role of GWAS SNPs in PMS2 mutation carriers. A cohort study was performed in 507 PMS2 carriers (124 CRC cases), genotyped for 24 GWAS SNPs, including SNPs at 11q23.1 and 8q23.3. Hazard ratios (HRs) were calculated using a weighted Cox regression analysis to correct for ascertainment bias. Discrimination was assessed with a concordance statistic in a bootstrap cross-validation procedure. Individual SNPs only had non-significant associations with CRC occurrence with HRs lower than 2, although male carriers of allele A at rs1321311 (6p21.31) may have increased risk of CRC (HR = 2.1, 95% CI 1.2-3.0). A polygenic risk score (PRS) based on 24 HRs had an HR of 2.6 (95% CI 1.5-4.6) for the highest compared to the lowest quartile, but had no discriminative ability (c statistic 0.52). Previously suggested SNPs do not modify CRC risk in PMS2 carriers. Future large studies are needed for improved risk stratification among Lynch syndrome patients.

Background & Aims: Germline variants in mismatch repair genes MLH1, MSH2 (EPCAM), MSH6, or PMS2 cause Lynch syndrome. Patients with these variants have an increased risk of developing colorectal cancers (CRCs) that differ from sporadic CRCs in genetic and histologic features. It has been a challenge to study CRCs associated with PMS2 variants (PMS2-associated CRCs) because these develop less frequently and in older patients than CRCs with variants in other mismatch repair genes., Methods: We analyzed 20 CRCs associated with germline variants in PMS2, 22 sporadic CRCs, 18 CRCs with germline variants in MSH2, and 24 CRCs from patients with germline variants in MLH1. Tumor tissue blocks were collected from Dutch pathology departments in 2017. After extraction of tumor DNA, we used a platform designed to detect approximately 3,000 somatic hotspot variants in 55 genes (including KRAS, APC, CTNNB1, and TP53). Somatic variant frequencies were compared using the Fisher exact test., Results: None of the PMS2-associated CRCs contained any somatic variants in the catenin-β 1 gene (CTNNB1), which encodes β-catenin, whereas 14 of 24 MLH1-associated CRCs (58%) contained variants in CTNNB1. Half the PMS2-associated CRCs contained KRAS variants, but only 20% of these were in hotspots that encoded G12D or G13D. These hotspot variants occurred more frequently in CRCs associated with variants in MLH1 (37.5%; P = .44) and MSH2 (71.4%; P = .035) than in those associated with variants in PMS2., Conclusions: In a genetic analysis of 84 colorectal tumors, we found tumors from patients with PMS2-associated Lynch syndrome to be distinct from colorectal tumors associated with defects in other mismatch repair genes. This might account for differences in development and less frequent occurrence., (Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Until recently, no prediction models for Lynch syndrome (LS) had been validated for PMS2 mutation carriers. We aimed to evaluate MMRpredict and PREMM5 in a clinical cohort and for PMS2 mutation carriers specifically. In a retrospective, clinic-based cohort we calculated predictions for LS according to MMRpredict and PREMM5. The area under the operator receiving characteristic curve (AUC) was compared between MMRpredict and PREMM5 for LS patients in general and for different LS genes specifically. Of 734 index patients, 83 (11%) were diagnosed with LS; 23 MLH1, 17 MSH2, 31 MSH6 and 12 PMS2 mutation carriers. Both prediction models performed well for MLH1 and MSH2 (AUC 0.80 and 0.83 for PREMM5 and 0.79 for MMRpredict) and fair for MSH6 mutation carriers (0.69 for PREMM5 and 0.66 for MMRpredict). MMRpredict performed fair for PMS2 mutation carriers (AUC 0.72), while PREMM5 failed to discriminate PMS2 mutation carriers from non-mutation carriers (AUC 0.51). The only statistically significant difference between PMS2 mutation carriers and non-mutation carriers was proximal location of colorectal cancer (77 vs. 28%, p < 0.001). Adding location of colorectal cancer to PREMM5 considerably improved the models performance for PMS2 mutation carriers (AUC 0.77) and overall (AUC 0.81 vs. 0.72). We validated these results in an external cohort of 376 colorectal cancer patients, including 158 LS patients. MMRpredict and PREMM5 cannot adequately identify PMS2 mutation carriers. Adding location of colorectal cancer to PREMM5 may improve the performance of this model, which should be validated in larger cohorts.

Constitutional mismatch repair deficiency (CMMRD) is a rare, recessively inherited childhood cancer predisposition syndrome caused by biallelic germline mutations in one of the mismatch repair genes. The CMMRD phenotype overlaps with that of neurofibromatosis type 1 (NF1), since many patients have multiple café-au-lait macules (CALM) and other NF1 signs, but no germline NF1 mutations. We report of a case of a healthy 6-year-old girl who fulfilled the diagnostic criteria of NF1 with >6 CALM and freckling. Since molecular genetic testing was unable to confirm the diagnosis of NF1 or Legius syndrome and the patient was a child of consanguineous parents, we suspected CMMRD and found a homozygous PMS2 mutation that impairs MMR function. Current guidelines advise testing for CMMRD only in cancer patients. However, this case illustrates that including CMMRD in the differential diagnosis in suspected sporadic NF1 without causative NF1 or SPRED1 mutations may facilitate identification of CMMRD prior to cancer development. We discuss the advantages and potential risks of this CMMRD testing scenario., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Mutations in the myosin heavy chain 7 (MYH7) gene commonly cause cardiomyopathy but are less frequently associated with congenital heart defects., Methods: In this study, we describe a mutation in the MYH7 gene, c. 5754C > G; p. (Asn1918Lys), present in 15 probands and 65 family members., Results: Of the 80 carriers (age range 0-88 years), 46 (57.5%) had cardiomyopathy (mainly dilated cardiomyopathy (DCM)) and seven (8.8%) had a congenital heart defect. Childhood onset of cardiomyopathy was present in almost 10% of carriers. However, in only a slight majority (53.7%) was the left ventricular ejection fraction reduced and almost no arrhythmias or conduction disorders were noted. Moreover, only one carrier required heart transplantation and nine (11.3%) an implantable cardioverter defibrillator. In addition, the standardised mortality ratio for MYH7 carriers was not significantly increased. Whole exome sequencing in several cases with paediatric onset of DCM and one with isolated congenital heart defects did not reveal additional known disease-causing variants. Haplotype analysis suggests that the MYH7 variant is a founder mutation, and is therefore the first Dutch founder mutation identified in the MYH7 gene. The mutation appears to have originated in the western region of the province of South Holland between 500 and 900 years ago., Conclusion: Clinically, the p. (Asn1918Lys) mutation is associated with congenital heart defects and/or cardiomyopathy at young age but with a relatively benign course.

Monoallelic PMS2 germline mutations cause 5%-15% of Lynch syndrome, a midlife cancer predisposition, whereas biallelic PMS2 mutations cause approximately 60% of constitutional mismatch repair deficiency (CMMRD), a rare childhood cancer syndrome. Recently improved DNA- and RNA-based strategies are applied to overcome problematic PMS2 mutation analysis due to the presence of pseudogenes and frequent gene conversion events. Here, we determined PMS2 mutation detection yield and mutation spectrum in a nationwide cohort of 396 probands. Furthermore, we studied concordance between tumor IHC/MSI (immunohistochemistry/microsatellite instability) profile and mutation carrier state. Overall, we found 52 different pathogenic PMS2 variants explaining 121 Lynch syndrome and nine CMMRD patients. In vitro mismatch repair assays suggested pathogenicity for three missense variants. Ninety-one PMS2 mutation carriers (70%) showed isolated loss of PMS2 in their tumors, for 31 (24%) no or inconclusive IHC was available, and eight carriers (6%) showed discordant IHC (presence of PMS2 or loss of both MLH1 and PMS2). Ten cases with isolated PMS2 loss (10%; 10/97) harbored MLH1 mutations. We confirmed that recently improved mutation analysis provides a high yield of PMS2 mutations in patients with isolated loss of PMS2 expression. Application of universal tumor prescreening methods will however miss some PMS2 germline mutation carriers., (© 2016 WILEY PERIODICALS, INC.)

Purpose: Lynch syndrome (LS), a heritable disorder with an increased risk of primarily colorectal cancer (CRC) and endometrial cancer (EC), can be caused by mutations in the PMS2 gene. We wished to establish whether genotype and/or parent-of-origin effects (POE) explain (part of) the reported variability in severity of the phenotype., Methods: European PMS2 mutation carriers (n = 381) were grouped and compared based on RNA expression and whether the mutation was inherited paternally or maternally., Results: Mutation carriers with loss of RNA expression (group 1) had a significantly lower age at CRC diagnosis (51.1 years vs. 60.0 years, P = 0.035) and a lower age at EC diagnosis (55.8 years vs. 61.0 years, P = 0.2, nonsignificant) compared with group 2 (retention of RNA expression). Furthermore, group 1 showed slightly higher, but nonsignificant, hazard ratios (HRs) for both CRC (HR: 1.31, P = 0.38) and EC (HR: 1.22, P = 0.72). No evidence for a significant parent-of-origin effect was found for either CRC or EC., Conclusions: PMS2 mutation carriers with retention of RNA expression developed CRC 9 years later than those with loss of RNA expression. If confirmed, this finding would justify a delay in surveillance for these cases. Cancer risk was not influenced by a parent-of-origin effect.Genet Med 18 4, 405-409.

Purpose: The clinical consequences of PMS2 germline mutations are poorly understood compared with other Lynch-associated mismatch repair gene (MMR) mutations. The aim of this European cohort study was to define the cancer risk faced by PMS2 mutation carriers., Methods: Data were collected from 98 PMS2 families ascertained from family cancer clinics that included a total of 2,548 family members and 377 proven mutation carriers. To adjust for potential ascertainment bias, a modified segregation analysis model was used to calculate colorectal cancer (CRC) and endometrial cancer (EC) risks. Standardized incidence ratios (SIRs) were calculated to estimate risks for other Lynch syndrome-associated cancers., Results: The cumulative risk (CR) of CRC for male mutation carriers by age 70 years was 19%. The CR among female carriers was 11% for CRC and 12% for EC. The mean age of CRC development was 52 years, and there was a significant difference in mean age of CRC between the probands (mean, 47 years; range, 26 to 68 years) and other family members with a PMS2 mutation (mean, 58 years; range, 31 to 86 years; P < .001). Significant SIRs were observed for cancers of the small bowel, ovaries, breast, and renal pelvis., Conclusion: CRC and EC risks were found to be markedly lower than those previously reported for the other MMR. However, these risks embody the isolated risk of carrying a PMS2 mutation, and it should be noted that we observed a substantial variation in cancer phenotype within and between families, suggesting the influence of genetic modifiers and lifestyle factors on cancer risks., (© 2014 by American Society of Clinical Oncology.)