Lynch Syndrome - HNPCC

Overview

Lynch Syndrome or Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant disease characterised by early onset of colorectal cancer and increased risk of other malignancies including endometrial and renal cell carcinomas. HNPCC is associated with germline mutations of DNA mismatch repair genes, individuals who inherit HNPCC have an 80% lifetime risk of developing colorectal cancer.

In a study of 48 HNPCC kindreds (Liu et al, 1996) identified mutations in known mismatch repair genes;
31%: had mutations in the MSH2 gene
33%, had mutations in the MLH1 gene
2%, had mutations in the PMS1 gene
4% had mutations in the PMS2 gene

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 10 March, 2017 using data from PubMed, MeSH and CancerIndex

Mutated Genes and Abnormal Protein Expression (16)

How to use this data tableClicking on the Gene or Topic will take you to a separate more detailed page. Sort this list by clicking on a column heading e.g. 'Gene' or 'Topic'.

GeneLocationAliasesNotesTopicPapers
MLH1 3p21.3 FCC2, COCA2, HNPCC, hMLH1, HNPCC2 Germline
-MLH1 and Lynch Syndrome
1080
MSH2 2p21 FCC1, COCA1, HNPCC, LCFS2, HNPCC1 -MSH2 and Lynch Syndrome
1058
MSH6 2p16 GTBP, HSAP, p160, GTMBP, HNPCC5 -MSH6 and Lynch Syndrome
370
PMS2 7p22.1 MLH4, PMSL2, HNPCC4, PMS2CL -PMS2 and Lynch Syndrome
335
PMS1 2q31.1 MLH2, PMSL1, hPMS1, HNPCC3 -PMS1 and Lynch Syndrome
53
MSH3 5q14.1 DUP, MRP1 -MSH3 and Lynch Syndrome
37
TGFBR2 3p22 AAT3, FAA3, LDS2, MFS2, RIIC, LDS1B, LDS2B, TAAD2, TGFR-2, TGFbeta-RII -TGFBR2 and Lynch Syndrome
36
MUTYH 1p34.1 MYH -MUTYH and Lynch Syndrome
32
EPCAM 2p21 ESA, KSA, M4S1, MK-1, DIAR5, EGP-2, EGP40, KS1/4, MIC18, TROP1, EGP314, HNPCC8, TACSTD1 -EPCAM and Lynch Syndrome
25
MLH3 14q24.3 HNPCC7 -MLH3 and Lynch Syndrome
19
EXO1 1q43 HEX1, hExoI -EXO1 and Lynch Syndrome
9
PRINS 10p12.1 NCRNA00074 -PRINS and Lynch Syndrome
5
CASP5 11q22.3 ICH-3, ICEREL-III, ICE(rel)III -CASP5 and Lynch Syndrome
4
SEC63 6q21 ERdj2, SEC63L, DNAJC23, PRO2507 -SEC63 and Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
3
AIM2 1q22 PYHIN4 -AIM2 and Lynch Syndrome
3
POLD1 19q13.3 CDC2, MDPL, POLD, CRCS10 -POLD1 and Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
2

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications

Chen W, Ding J, Jiang L, et al.
DNA copy number profiling in microsatellite-stable and microsatellite-unstable hereditary non-polyposis colorectal cancers by targeted CNV array.
Funct Integr Genomics. 2017; 17(1):85-96 [PubMed] Related Publications
About half of hereditary non-polyposis colorectal cancers (HNPCCs) fulfilling the Amsterdam criteria (AC) do not display evidence of mismatch repair defects, and the difference between microsatellite-stable (MSS) and microsatellite-unstable HNPCC remains poorly understood. The study was to compare overall copy number variation (CNV) and loss of heterozygosity (LOH) of the entire genome in HNPCCs with MSS and microsatellite-instability (MSI) using the Cytoscan HD Array. This was a study carried out in samples from 20 patients with MSS HNPCC and four patients with MSI HNPCC from the Fudan University Shanghai Cancer Center (China). The microsatellite status was examined using a panel of microsatellite markers. MMR expression status was evaluated by immunohistochemistry. Tumor samples were analyzed with the Genome-Wide Human CytoScan HD Array. CNV and LOH were determined. Fourteen specific CNVs (eight gains: 5p13.1, 7p13, 7q22.3, 8q11.21, 8q12.2, 19q13.11, 20q11.21, and 20q11.23; and six losses: 8p22, 8p23.1, 8p23.1, 17p13.1, 17p13.2, and 18q21.3) were associated with MSS HNPCC. Of these 14 CNVs, gain on 8q12.2 and loss on 17p13.1 were novel. The total length of 8q gains and 20q gains were greater in MSS tumors than in MSI (P < 0.05). The presence of similar levels of copy-neutral-LOH in MSS (31.7%) and MSI (29.7%) HNPCC suggested that unknown DNA repair genes might be involved in the tumorigenesis of MSS HNPCC. MSS HNPCC is a genetically specific population with increased CNV, which are different from MSI HNPCC. The results may help to clarify the genetic basis of MSS HNPCC tumorigenesis.

Kacerovska D, Drlik L, Slezakova L, et al.
Cutaneous Sebaceous Lesions in a Patient With MUTYH-Associated Polyposis Mimicking Muir-Torre Syndrome.
Am J Dermatopathol. 2016; 38(12):915-923 [PubMed] Related Publications
A 76-year-old white male with a history of adenocarcinoma of the rectosigmoideum and multiple colonic polyps removed at the age of 38 and 39 years by an abdominoperitoneal amputation and total colectomy, respectively, presented with multiple whitish and yellowish papules on the face and a verrucous lesion on the trunk. The lesions were surgically removed during the next 3 years and a total of 13 lesions were investigated histologically. The diagnoses included 11 sebaceous adenomas, 1 low-grade sebaceous carcinoma, and 1 squamous cell carcinoma. In some sebaceous lesions, squamous metaplasia, intratumoral heterogeneity, mucinous changes, and peritumoral lymphocytes as sometimes seen in sebaceous lesions in Muir-Torre syndrome were noted. Mutation analysis of the peripheral blood revealed a germline mutation c.692G>A,p.(Arg231His) in exon 9 and c.1145G>A, p.(Gly382Asp) in exon 13 of the MUTYH gene. A KRAS mutation G12C (c.34G>T, p.Gly12Cys) was detected in 1 sebaceous adenoma and a NRAS mutation Q61K (c.181C>A, p.Gln61Lys) was found in 2 other sebaceous adenomas. No germline mutations in MLH1, MSH2, MSH6 and PMS2 genes, no microsatellite instability, no aberrant methylation of MLH1 promoter, and no somatic mutations in MSH2 and MSH6 were found. An identical MUTYH germline mutation was found in the patient's daughter. Despite striking clinicopathological similarities with Muir-Torre syndrome, the molecular biologic testing confirmed the final diagnosis of MUTYH-associated polyposis.

Farahani N, Nikpou P, Emami MH, et al.
Evaluation of MT1XT20 Single Quasi-Monomorphic Mononucleotide Marker for Characterizing Microsatellite Instability in Persian Lynch Syndrome Patients.
Asian Pac J Cancer Prev. 2016; 17(9):4259-4265 [PubMed] Related Publications
BACKGROUND: Colorectal malignancies with high microsatellite instability (MSI-H), either hereditary (Lynch syndrome) or sporadic, demonstrate better prognosis and altered response to 5FU chemotherapy. It is now recommended to perform MSI testing for all new cases of colorectal cancer regardless of being categorized as hereditary or sporadic. For MSI detection, immunohistochemistry or PCR-based protocols using a cohort of various sets of STR markers are recommended. Here we aimed to evaluate a simplified protocol using just a single STR marker, MT1XT20 mononucleotide repeat, for detection of MSI in Lynch syndrome patients. A Promega five-marker MSI testing panel and immunohistochemistry (IHC) were used as the gold standard in conjunction with MT1XT20.
MATERIALS AND METHODS: Colorectal patients with a positive history of familial cancers were selected by evaluating medical records. Based on Amsterdam II criteria for Lynch syndrome 20 families were short listed. DNA was extracted from formalin fixed paraffin embedded tumour and adjacent normal tissues resected from the index case in each family. Extracted DNA was subjected to MT1XT20 mononucleotide marker analysis and assessment with a commercially available five marker MSI testing kit (Promega, USA). IHC also was performed on tissue sections and the results were compared with PCR based data.
RESULTS: Eight (40%), seven (35%) and five (25%) cases were MSI positive using with the Promega kit, IHC and MT1XT20, respectively. Among the markers included in Promega kit, BAT26 marker showed instability in all 8 samples. NR24 and NR21 markers showed instability in 7 (87.5%), and BAT25 and MONO 27 in 6 (75%) and 5 (62.5%).
CONCLUSIONS: Although MT1XT20 was earlier reported as a valid standalone marker for MSI testing in CRC patients, we could not verify this in our Iranian patients. Instead BAT26 among the markers included in Promega MSI testing kit showed instability in all 8 MSI-H CRC samples. Therefore, it seems BAT26 could act well as a single marker for MSI testing in Iranian CRC patients.

Bouguenouch L, Samri I, Belhassan K, et al.
[Lynch syndrome: case report and review of the literature].
Pan Afr Med J. 2016; 24:142 [PubMed] Free Access to Full Article Related Publications
Lynch syndrome or hereditary nonpolyposis colorectal cancer (HNPCC) is the most common form of hereditary colorectal cancers. It increases cancer susceptibility, the risk of colorectal cancer in first-degree, endometrial cancer in women, and to a lesser extent, other cancers (ovarian, small bowel, stomach, urinary tract and hepatobiliary). Thus, the cumulative risk of developing colorectal cancer or endometrial cancer at the age of 80 years rises to 20 and 40% respectively. These cancers are characterized by a positive family history, their occurrence at an early age, and by the development of metachronous cancers in the same individual. This syndrome is transmitted in an autosomal dominant manner. The genes whose alteration is associated with the presence of an HNPCC belong to the family of DNA mismatch repair genes (DNA mismatch repair or MMR): MSH2, MLH1, and MSH6 are involved, in decreasing order of frequency, in 35%, 25% and 2% of cases respectively. Colonoscopic and gynecological monitoring is recommended for patients with a constitutional mutation in MSH2, MLH1 or Msh6 genes. We report one of the first moroccan case with Lynch syndrome whose constitutional mutation in the MLH1 gene was identified in a family member with colon cancer. In reply to the inquiry ofother healthy family members, a presymptomatic diagnosis was made allowing to formulate an appropriate monitoring strategy. Our study aims to highlight the role of oncogenetics in the management of patients with cancer and their families.

DA Silva FC, Wernhoff P, Dominguez-Barrera C, Dominguez-Valentin M
Update on Hereditary Colorectal Cancer.
Anticancer Res. 2016; 36(9):4399-405 [PubMed] Related Publications
In the past two decades, significant advances have been made in our understanding of colorectal (CRC) tumors with DNA mismatch (MMR) repair deficiency. The knowledge from molecular and genetic alterations in a variety of clinical conditions has refined the disease terminology and classification. Hereditary non-polyposis colorectal cancer (HNPCC) encompasses a spectrum of conditions that have significant phenotypic overlapping that makes clinical diagnosis a challenging task. Distinguishing among the HNPCC disorders is clinically important, as the approach to surveillance for patients and their at-risk family members differs according to risks for colonic and extracolonic cancer associated with each syndrome. Prospective and next-generation studies will provide valuable clinical information regarding the natural history of disease that will help differentiate the Lynch syndrome mimics and guide diagnosis and management for heterogeneous conditions currently grouped under the category of familial CRC. The review is intended to present and discuss the molecular nature of various conditions related to MMR deficiency and discusses the tools and strategies that have been used in detecting these conditions.

Rubio I, Ibáñez-Feijoo E, Andrés L, et al.
Analysis of Lynch Syndrome Mismatch Repair Genes in Women with Endometrial Cancer.
Oncology. 2016; 91(3):171-6 [PubMed] Related Publications
OBJECTIVE: Endometrial cancer is the second most frequent neoplasm in women with Lynch syndrome (LS). We sought to assess whether analyzing women with endometrial cancer would identify families with LS not identified with current clinical criteria.
METHODS: We included women diagnosed with endometrial cancer younger than 50 years and also older if they had a family cancer history associated with LS. In blood samples obtained, we analyzed mutations in mismatch repair (MMR) genes, as well as protein expression by immunohistochemistry and microsatellite instability (MSI) in tumour tissue.
RESULTS: A total of 103 patients were enrolled. We detected 14 pathogenic mutations and 4 genetic variants of unknown clinical significance in MMR genes. We found MSI in 41.66% of the women with a pathogenic mutation. In this group, 76.92% showed loss of at least one MMR protein. Women with mutations were younger at diagnosis, but all of them had a family history compatible with LS.
CONCLUSIONS: Analysis of the MMR genes, in particular MSH6, seems to be appropriate in women with endometrial cancer and a family history of tumours associated with LS.

Boissière-Michot F, Frugier H, Ho-Pun-Cheung A, et al.
Immunohistochemical staining for p16 and BRAFV600E is useful to distinguish between sporadic and hereditary (Lynch syndrome-related) microsatellite instable colorectal carcinomas.
Virchows Arch. 2016; 469(2):135-44 [PubMed] Related Publications
DNA mismatch repair (MMR) protein analysis by immunohistochemistry (IHC) can identify colorectal cancer (CRC) with microsatellite instability (MSI). As MLH1-deficient CRC can be hereditary or sporadic, markers to distinguish between them are needed. MLH1 promoter methylation assay is the reference method; however, sometimes, it is challenging on formalin-fixed paraffin-embedded tissue samples. We assessed by IHC the expression of BRAFV600E, p16, MGMT, and CDX2 in 55 MLH1-deficient MSI CRC samples (of which 8 had a germline MLH1 mutation) to determine whether this panel differentiates between sporadic and hereditary CRCs. We also analyzed MLH1 promoter methylation by methylation-specific PCR and pyrosequencing and BRAF status by genotyping. None of the hereditary CRCs showed MLH1 methylation, BRAF mutation, BRAFV600E-positive immunostaining, or loss of p16 expression. We detected MLH1 promoter methylation in 67 % and a BRAF mutation in 42 % of CRC, all showing MLH1 promoter methylation. BRAFV600E IHC and BRAF genotyping gave concordant results in all but two samples. Loss of expression of p16 was found in 30 % of CRC with methylation of the MLH1 promoter, but its expression was retained in all non-methylated and part of MLH1-methylated tumors (100 % specificity, 30 % sensitivity). CDX2 and MGMT expression was not associated with MLH1 status. Thus, BRAFV600E and p16 IHC may help in differentiating sporadic from hereditary MLH1-deficient CRC with MSI. Specifically, p16 IHC might be used as a surrogate marker for MLH1 promoter methylation, because all p16-negative CRCs displayed MLH1 methylation, whereas hereditary CRCs were all p16-positive.

Tanakaya K, Yamaguchi T, Ishikawa H, et al.
Causes of Cancer Death Among First-Degree Relatives in Japanese Families with Lynch Syndrome.
Anticancer Res. 2016; 36(4):1985-9 [PubMed] Related Publications
AIM: To elucidate the causes of cancer death in Japanese families with Lynch syndrome (LS).
METHODS: The distributions of cancer deaths in 485 individuals from 67 families with LS (35, 30, and two families with MutL homologue 1 (MLH1), MSH2, and MSH6 gene mutations, respectively), obtained from the Registry of the Japanese Society for Cancer of the Colon and Rectum were analyzed.
RESULTS: Among 98 cancer deaths of first-degree relatives of unknown mutation status, 53%, 19%, 13% (among females), 7% (among females) and 5% were due to colorectal, gastric, uterine, ovarian, and hepatobiliary cancer, respectively. The proportion of deaths from extra-colonic cancer was significantly higher in families with MSH2 mutation than in those with MLH1 mutation (p=0.003).
CONCLUSION: In addition to colonic and uterine cancer, management and surveillance targeting gastric, ovarian and hepatobiliary cancer are considered important for Japanese families with LS. Extra-colonic cancer in families with MSH2 mutation might require for more intensive surveillance.

Wang M, Aldubayan S, Connor AA, et al.
Genetic testing for Lynch syndrome in the province of Ontario.
Cancer. 2016; 122(11):1672-9 [PubMed] Related Publications
BACKGROUND: In November 2001, genetic testing for Lynch syndrome (LS) was introduced by the Ministry of Health and Long-Term Care (MOH) in Ontario for individuals at high risk for LS cancers according to either tumor immunohistochemistry staining or their family history. This article describes the outcomes of the program and makes recommendations for improving it and informing other public health care programs.
METHODS: Subjects were referred for molecular testing of the mismatch repair (MMR) genes MutL homolog 1, MutS homolog 2, and MutS homolog 6 if they met 1 of 7 MOH criteria. Testing was conducted from January 2001 to March 2015 at the Molecular Diagnostic Laboratory of Mount Sinai Hospital in Toronto.
RESULTS: A total of 1452 subjects were tested. Of the 662 subjects referred for testing because their tumor was immunodeficient for 1 or more of the MMR genes, 251 (37.9%) carried a germline mutation. In addition, 597 subjects were tested for a known family mutation, and 298 (49.9%) were positive; 189 of these 298 subjects (63.4%) were affected with cancer at the time of testing. An additional 193 subjects were referred because of a family history of LS, and 34 of these (17.6%) had a mutation identified.
CONCLUSIONS: These results indicate that the provincial criteria are useful in identifying LS carriers after an MMR-deficient tumor is identified. Placing greater emphasis on testing unaffected relatives in families with a known mutation may identify more unaffected carriers and facilitate primary prevention in those individuals. Cancer 2016;122:1672-9. © 2016 American Cancer Society.

Ponti G, Manfredini M, Pellacani G, Tomasi A
Role of microsatellite instability, immunohistochemistry and mismatch repair germline aberrations in immunosuppressed transplant patients: a phenocopy dilemma in Muir-Torre syndrome.
Clin Chem Lab Med. 2016; 54(11):1725-1731 [PubMed] Related Publications
Sebaceous tumours and keratoacanthomas are uncommon neoplasms that constitute important clinical criteria for Muir-Torre syndrome (MTS) diagnosis. In MTS patients, the increased risk of developing synchronous or metachronous visceral malignancies is characterised by autosomal dominant inheritance. However, there are further conditions, other than MTS, that increase the risk of sebaceous neoplasms, e.g. iatrogenic immunosuppression. In this latter scenario, the sebaceous tumours can present microsatellite instability (MSI) and loss of mismatch repair (MMR) proteins, characteristic of hereditary syndromes, even in the absence of MMR germline mutations. In this article, we examine transplant probands in which the immunosuppressive therapies unmask the MTS cutaneous phenotypes, showing MSI and loss of MMR protein expression, as demonstrated by immunohistochemistry (IHC). Furthermore, MMR genes sequencing analysis identified the presence of germline mutations in MTS-suspected individuals, in the absence of a visceral MTS phenotype. It is well known that immunosuppression plays a central role in the development of sebaceous tumours in both MTS and in non-syndromic settings. Sebaceous skin tumours' MSI status and IHC profiles can be influenced by epigenetic or iatrogenic factors; however, they constitute valuable tools and a cost-effective approach to screen individuals who otherways should undergo MMR genes direct sequencing in the context of immunosuppression. In this complex setting, the choice of the immunosuppressive drug becomes a critical decision for the management of both MTS and sporadic transplant patients, which may benefit from the administration of immunosuppressive drugs, resulting in a low impact on skin cancerogenesis.

Dominguez-Valentin M, Joost P, Therkildsen C, et al.
Frequent mismatch-repair defects link prostate cancer to Lynch syndrome.
BMC Urol. 2016; 16:15 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: A possible role for prostate cancer in Lynch syndrome has been debated based on observations of mismatch-repair defective tumors and reports of an increased risk of prostate cancer in mutation carriers. Potential inclusion of prostate cancer in the Lynch syndrome tumor spectrum is relevant for family classification, risk estimates and surveillance recommendations in mutation carriers.
METHODS: We used the population-based Danish HNPCC-register to identify all prostate cancers that developed in mutation carriers and in their first-degree relatives from 288 Lynch syndrome families. The tumors were evaluated for clinicopathologic features and mismatch-repair status, and the cumulative risk of prostate cancer was determined.
RESULTS: In total, 28 prostate cancers developed in 16 mutation carriers and in 12 first-degree relatives at a median age of 63 years. The majority of the tumors were high-grade tumors with Gleason scores 8-10. Prostate cancer was associated with mutations in MSH2, MLH1 and MSH6 with loss of the respective mismatch repair protein in 69 % of the tumors, though a MSI-high phenotype was restricted to 13 % of the tumors. The cumulative risk of prostate cancer at age 70 was 3.7 % (95 % CI: 2.3-4.9).
CONCLUSION: We provide evidence to link prostate cancer to Lynch syndrome through demonstration of MMR defective tumors and an increased risk of the disease, which suggests that prostate cancer should be considered in the diagnostic work-up of Lynch syndrome.

Taylor N, Long JC, Debono D, et al.
Achieving behaviour change for detection of Lynch syndrome using the Theoretical Domains Framework Implementation (TDFI) approach: a study protocol.
BMC Health Serv Res. 2016; 16:89 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Lynch syndrome is an inherited disorder associated with a range of cancers, and found in 2-5 % of colorectal cancers. Lynch syndrome is diagnosed through a combination of significant family and clinical history and pathology. The definitive diagnostic germline test requires formal patient consent after genetic counselling. If diagnosed early, carriers of Lynch syndrome can undergo increased surveillance for cancers, which in turn can prevent late stage cancers, optimise treatment and decrease mortality for themselves and their relatives. However, over the past decade, international studies have reported that only a small proportion of individuals with suspected Lynch syndrome were referred for genetic consultation and possible genetic testing. The aim of this project is to use behaviour change theory and implementation science approaches to increase the number and speed of healthcare professional referrals of colorectal cancer patients with a high-likelihood risk of Lynch syndrome to appropriate genetic counselling services.
METHODS: The six-step Theoretical Domains Framework Implementation (TDFI) approach will be used at two large, metropolitan hospitals treating colorectal cancer patients. Steps are: 1) form local multidisciplinary teams to map current referral processes; 2) identify target behaviours that may lead to increased referrals using discussion supported by a retrospective audit; 3) identify barriers to those behaviours using the validated Influences on Patient Safety Behaviours Questionnaire and TDFI guided focus groups; 4) co-design interventions to address barriers using focus groups; 5) co-implement interventions; and 6) evaluate intervention impact. Chi square analysis will be used to test the difference in the proportion of high-likelihood risk Lynch syndrome patients being referred for genetic testing before and after intervention implementation. A paired t-test will be used to assess the mean time from the pathology test results to referral for high-likelihood Lynch syndrome patients pre-post intervention. Run charts will be used to continuously monitor change in referrals over time, based on scheduled monthly audits.
DISCUSSION: This project is based on a tested and refined implementation strategy (TDFI approach). Enhancing the process of identifying and referring people at high-likelihood risk of Lynch syndrome for genetic counselling will improve outcomes for patients and their relatives, and potentially save public money.

Houlleberghs H, Dekker M, Lantermans H, et al.
Oligonucleotide-directed mutagenesis screen to identify pathogenic Lynch syndrome-associated MSH2 DNA mismatch repair gene variants.
Proc Natl Acad Sci U S A. 2016; 113(15):4128-33 [PubMed] Free Access to Full Article Related Publications
Single-stranded DNA oligonucleotides can achieve targeted base-pair substitution with modest efficiency but high precision. We show that "oligo targeting" can be used effectively to study missense mutations in DNA mismatch repair (MMR) genes. Inherited inactivating mutations in DNA MMR genes are causative for the cancer predisposition Lynch syndrome (LS). Although overtly deleterious mutations in MMR genes can clearly be ascribed as the cause of LS, the functional implications of missense mutations are often unclear. We developed a genetic screen to determine the pathogenicity of these variants of uncertain significance (VUS), focusing on mutator S homolog 2 (MSH2). VUS were introduced into the endogenous Msh2 gene of mouse embryonic stem cells by oligo targeting. Subsequent selection for MMR-deficient cells using the guanine analog 6-thioguanine allowed the detection of MMR-abrogating VUS. The screen was able to distinguish weak and strong pathogenic variants from polymorphisms and was used to investigate 59 Msh2 VUS. Nineteen of the 59 VUS were identified as pathogenic. Functional assays revealed that 14 of the 19 detected variants fully abrogated MMR activity and that five of the detected variants attenuated MMR activity. Implementation of the screen in clinical practice allows proper counseling of mutation carriers and treatment of their tumors.

Rosty C, Clendenning M, Walsh MD, et al.
Germline mutations in PMS2 and MLH1 in individuals with solitary loss of PMS2 expression in colorectal carcinomas from the Colon Cancer Family Registry Cohort.
BMJ Open. 2016; 6(2):e010293 [PubMed] Free Access to Full Article Related Publications
OBJECTIVES: Immunohistochemistry for DNA mismatch repair proteins is used to screen for Lynch syndrome in individuals with colorectal carcinoma (CRC). Although solitary loss of PMS2 expression is indicative of carrying a germline mutation in PMS2, previous studies reported MLH1 mutation in some cases. We determined the prevalence of MLH1 germline mutations in a large cohort of individuals with a CRC demonstrating solitary loss of PMS2 expression.
DESIGN: This cohort study included 88 individuals affected with a PMS2-deficient CRC from the Colon Cancer Family Registry Cohort. Germline PMS2 mutation analysis (long-range PCR and multiplex ligation-dependent probe amplification) was followed by MLH1 mutation testing (Sanger sequencing and multiplex ligation-dependent probe amplification).
RESULTS: Of the 66 individuals with complete mutation screening, we identified a pathogenic PMS2 mutation in 49 (74%), a pathogenic MLH1 mutation in 8 (12%) and a MLH1 variant of uncertain clinical significance predicted to be damaging by in silico analysis in 3 (4%); 6 (9%) carried variants likely to have no clinical significance. Missense point mutations accounted for most alterations (83%; 9/11) in MLH1. The MLH1 c.113A> G p.Asn38Ser mutation was found in 2 related individuals. One individual who carried the MLH1 intronic mutation c.677+3A>G p.Gln197Argfs*8 leading to the skipping of exon 8, developed 2 tumours, both of which retained MLH1 expression.
CONCLUSIONS: A substantial proportion of CRCs with solitary loss of PMS2 expression are associated with a deleterious MLH1 germline mutation supporting the screening for MLH1 in individuals with tumours of this immunophenotype, when no PMS2 mutation has been identified.

Liu Q, Thompson BA, Ward RL, et al.
Understanding the Pathogenicity of Noncoding Mismatch Repair Gene Promoter Variants in Lynch Syndrome.
Hum Mutat. 2016; 37(5):417-26 [PubMed] Related Publications
Lynch syndrome is the most common familial cancer condition that mainly predisposes to tumors of the colon and endometrium. Cancer susceptibility is caused by the autosomal dominant inheritance of a loss-of-function mutation or epimutation in one of the DNA mismatch repair (MMR) genes. Cancer risk assessment is often possible with nonsynonymous coding region mutations, but in many cases patients present with DNA sequence changes within noncoding regions, including the promoters, of MMR genes. The pathogenic role of promoter variants, and hence clinical significance, is unclear and this hinders the clinical management of carriers. In this review, we provide an overview of the classification of MMR gene variants, outline the laboratory assays and online resources that can be used to assess the causality of promoter variants in Lynch syndrome, and highlight some of the practical challenges of demonstrating the pathogenicity of these variants. In conclusion, we propose a guide that could be integrated into the current InSiGHT classification scheme to help determine if a MMR gene promoter variant is pathogenic.

Soer EC, Leicher LW, Langers AM, et al.
Equivalent Helicobacter pylori infection rates in Lynch syndrome mutation carriers with and without a first-degree relative with gastric cancer.
Int J Colorectal Dis. 2016; 31(3):693-7 [PubMed] Related Publications
BACKGROUND: Patients with Lynch syndrome (LS) are at an increased risk of developing gastric cancer. In 2010, a guideline that recommended to screen all patients for Helicobacter pylori was implemented in the Netherlands. H. pylori is an important risk factor in the development of gastric cancer in the general population, and eradication of the bacterium reduces this risk. We aimed to assess the proportion of LS patients being tested and the yield and also addressed the question whether H. pylori infection is more prevalent in LS families with known cases of gastric cancer.
METHODS: Proven mutation carriers from five different Dutch hospitals were included. The implementation of H. pylori screening and its outcome was examined. The observation period was 2008-2013. The presence of first-degree family members with gastric cancer was noted, and it was observed if H. pylori infection was more prevalent in Lynch families with known cases of gastric cancer. Obtainable endoscopy reports were reviewed.
RESULTS: Four hundred forty-three (male, 184) proven mutation carriers were included. The proportion of patients screened increased after 2010, from 37 to 68%. Twenty percent of the patients were infected. The 25 patients who had a first-degree family member with gastric cancer did not have a higher infection rate. In 30% of cases, an endoscopy was performed; in four patients, intestinal metaplasia and in eight patients, gastric cancer was found.
CONCLUSION: The recommendation to screen for H. pylori is increasingly followed. The prevalence of infection in this patient group does not differ from the general population. Patients who had a first-degree family member with gastric cancer did not have a higher infection rate.

Hall MJ, Obeid EI, Schwartz SC, et al.
Genetic testing for hereditary cancer predisposition: BRCA1/2, Lynch syndrome, and beyond.
Gynecol Oncol. 2016; 140(3):565-74 [PubMed] Free Access to Full Article Related Publications
Obstetrician/gynecologists and gynecologic oncologists serve an integral role in the care of women at increased hereditary risk of cancer. Their contribution includes initial identification of high risk patients, screening procedures like bimanual exam, trans-vaginal ultrasound and endometrial biopsy, prophylaxis via TAH and/or BSO, and chemoprevention. Further, gynecologists also serve a central role in the management of the secondary repercussions of efforts to mitigate increased cancer risks, including vasomotor symptoms, sexual function, bone health, cardiovascular disease, and mental health. The past several years has seen multiple new high and moderate penetrance genes introduced into the clinical care of women at increased risk of gynecologic malignancy. Awareness of these new genes and the availability of new multi-gene panel tests is critical for providers on the front-line of women's health.

Clark CR, Starr TK
Mouse models for the discovery of colorectal cancer driver genes.
World J Gastroenterol. 2016; 22(2):815-22 [PubMed] Free Access to Full Article Related Publications
Colorectal cancer (CRC) constitutes a major public health problem as the third most commonly diagnosed and third most lethal malignancy worldwide. The prevalence and the physical accessibility to colorectal tumors have made CRC an ideal model for the study of tumor genetics. Early research efforts using patient derived CRC samples led to the discovery of several highly penetrant mutations (e.g., APC, KRAS, MMR genes) in both hereditary and sporadic CRC tumors. This knowledge has enabled researchers to develop genetically engineered and chemically induced tumor models of CRC, both of which have had a substantial impact on our understanding of the molecular basis of CRC. Despite these advances, the morbidity and mortality of CRC remains a cause for concern and highlight the need to uncover novel genetic drivers of CRC. This review focuses on mouse models of CRC with particular emphasis on a newly developed cancer gene discovery tool, the Sleeping Beauty transposon-based mutagenesis model of CRC.

Talseth-Palmer BA, Bauer DC, Sjursen W, et al.
Targeted next-generation sequencing of 22 mismatch repair genes identifies Lynch syndrome families.
Cancer Med. 2016; 5(5):929-41 [PubMed] Free Access to Full Article Related Publications
Causative germline mutations in mismatch repair (MMR) genes can only be identified in ~50% of families with a clinical diagnosis of the inherited colorectal cancer (CRC) syndrome hereditary nonpolyposis colorectal cancer (HNPCC)/Lynch syndrome (LS). Identification of these patients are critical as they are at substantially increased risk of developing multiple primary tumors, mainly colorectal and endometrial cancer (EC), occurring at a young age. This demonstrates the need to develop new and/or more thorough mutation detection approaches. Next-generation sequencing (NGS) was used to screen 22 genes involved in the DNA MMR pathway in constitutional DNA from 14 HNPCC and 12 sporadic EC patients, plus 2 positive controls. Several softwares were used for analysis and functional annotation. We identified 5 exonic indel variants, 42 exonic nonsynonymous single-nucleotide variants (SNVs) and 1 intronic variant of significance. Three of these variants were class 5 (pathogenic) or class 4 (likely pathogenic), 5 were class 3 (uncertain clinical relevance) and 40 were classified as variants of unknown clinical significance. In conclusion, we have identified two LS families from the sporadic EC patients, one without a family history of cancer, supporting the notion for universal MMR screening of EC patients. In addition, we have detected three novel class 3 variants in EC cases. We have, in addition discovered a polygenic interaction which is the most likely cause of cancer development in a HNPCC patient that could explain previous inconsistent results reported on an intronic EXO1 variant.

Chika N, Kumamoto K, Suzuki O, et al.
[A Family Affected by Lynch Syndrome Caused by MSH6 Germline Mutation].
Gan To Kagaku Ryoho. 2015; 42(12):2211-4 [PubMed] Related Publications
The clinical features of Lynch syndrome caused by MSH6 are not fully understood since very few cases have been described in Japan. We report 2 cases of Lynch syndrome with germline mutation of MSH6 in a family. Case 1: A 47-year-old man was referred to our department due to positive fecal occult blood test. He had family history of endometrial cancer and gastric cancer (mother), and bladder cancer (father). We performed sigmoidectomy for sigmoid cancer. The pathological findings revealed mucosal cancer (pTis, pN0, H0, P0, pStage 0). Since the patient met the revised Bethesda guidelines, we performed microsatellite instability (MSI) testing and immunohistochemistry for mismatch repair genes (MLH1, MSH2, MSH6, and PMS2) as screening for Lynch syndrome. MSI-high and loss of MSH6 were found. Based on these results, genetic testing of MSH6 revealed a frame-shift mutation in codon 604 (c. 1806-1809delAAG/p. Glu604LeufsX5). Case 2: The patient was a younger brother of case 1. The same mutation was detected in the MSH6 gene.

Stratton KL, Alanee S, Glogowski EA, et al.
Outcome of genetic evaluation of patients with kidney cancer referred for suspected hereditary cancer syndromes.
Urol Oncol. 2016; 34(5):238.e1-7 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
OBJECTIVE: To analyze patients with kidney cancer referred for evaluation at a high-volume genetics service at a comprehensive cancer center and identify factors associated with positive tests for hereditary cancer syndromes.
METHODS: A retrospective review of patients referred to the Clinical Genetics Service at Memorial Sloan-Kettering Cancer Center was performed, and patients with a personal history of kidney cancer were identified. Patient and disease characteristics were reviewed. In all, 4 variables including age at diagnosis of kidney tumor, presence of syndromic manifestations, family history of kidney cancer, and number of primary malignancies were evaluated for association with positive test results in 2 groups: patients tested for renal cell carcinoma syndromes and Lynch syndrome. Guidance for genetic testing strategy in patients with kidney cancer is provided.
RESULTS: Between 1999 and 2012, 120 patients with a history of kidney cancer were evaluated by the Clinical Genetics Service. The mean age at kidney cancer diagnosis was 52 years (interquartile range: 42-63), with 57% being women. A family history of kidney cancer was reported by 39 patients (33%). Time between diagnosis of first cancer and genetic consultation was <1 year in 54%, 2 to 5 years in 23%, and>5 years in the remaining 23%. Overall, 95 patients were tested for genetic abnormalities with 27 (28%) testing positive. Testing for renal cell carcinoma (RCC)-related syndromes was performed on 43 patients, with 13 testing positive (30%). Lynch syndrome testing was positive in 9 patients (32%) after 28 were tested. In RCC-associated syndromes, young age of diagnosis was associated with positive test results. Conversely, syndromic manifestations and increasing number of primary malignancies were associated with positive Lynch testing.
CONCLUSIONS: The discovery of inherited kidney cancer syndromes has provided a unique opportunity to identify patients at increased risk for cancer. Factors associated with positive genetic testing are unique to different syndromes. These data suggest that in kidney cancer patients evaluated for hereditary cancer syndromes, young age is associated with diagnosis of RCC syndromes, whereas syndromic manifestations and multiple primaries are found in Lynch syndrome. These results, along with clinical awareness, may be useful for practicing urologists to select patients with kidney cancer to refer for genetic counseling.

Heinen CD
Mismatch repair defects and Lynch syndrome: The role of the basic scientist in the battle against cancer.
DNA Repair (Amst). 2016; 38:127-34 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
We have currently entered a genomic era of cancer research which may soon lead to a genomic era of cancer treatment. Patient DNA sequencing information may lead to a personalized approach to managing an individual's cancer as well as future cancer risk. The success of this approach, however, begins not necessarily in the clinician's office, but rather at the laboratory bench of the basic scientist. The basic scientist plays a critical role since the DNA sequencing information is of limited use unless one knows the function of the gene that is altered and the manner by which a sequence alteration affects that function. The role of basic science research in aiding the clinical management of a disease is perhaps best exemplified by considering the case of Lynch syndrome, a hereditary disease that predisposes patients to colorectal and other cancers. This review will examine how the diagnosis, treatment and even prevention of Lynch syndrome-associated cancers has benefitted from extensive basic science research on the DNA mismatch repair genes whose alteration underlies this condition.

Hata K, Yamamoto Y, Kiyomatsu T, et al.
Hereditary gastrointestinal cancer.
Surg Today. 2016; 46(10):1115-22 [PubMed] Related Publications
Gastrointestinal (GI) cancer, including gastric and colorectal cancer, is a major cause of death worldwide. A substantial proportion of patients with GI cancer have a familial history, and several causative genes have been identified. Gene carriers with these hereditary GI syndromes often harbor several kinds of cancer at an early age, and genetic testing and specific surveillance may save their lives through early detection. Gastroenterologists and GI surgeons should be familiar with these syndromes, even though they are not always associated with a high penetrance of GI cancer. In this review, we provide an overview and discuss the diagnosis, genetic testing, and management of four major hereditary GI cancers: familial adenomatous polyposis, Lynch syndrome, hereditary diffuse gastric cancer, and Li-Fraumeni syndrome.

Shikama A, Minaguchi T, Matsumoto K, et al.
Clinicopathologic implications of DNA mismatch repair status in endometrial carcinomas.
Gynecol Oncol. 2016; 140(2):226-33 [PubMed] Related Publications
OBJECTIVE: Endometrial carcinoma is the most common malignancy in women with Lynch syndrome caused by mismatch repair (MMR) deficiency. We investigated the clinicopathologic significance of deficient MMR and Lynch syndrome presumed by MMR analyses in unselected endometrial carcinomas.
METHODS: We analyzed immunohistochemistry of MMR proteins (MLH1/MSH2/MSH6/PMS2) and MLH1 promoter methylation in primary endometrial carcinomas from 221 consecutive patients. Based on these results, tumors were categorized as sporadic or probable Lynch syndrome (PLS). Clinicopathologic variables and prognosis were compared according to MMR status and sporadic/PLS classification.
RESULTS: Deficient MMR showed only trends towards favorable overall survival (OS) compared with intact MMR (p=0.13), whereas PLS showed significantly better OS than sporadic (p=0.038). Sporadic was significantly associated with older age, obesity, deep myometrial invasion, and advanced stage (p=0.008, 0.01, 0.02 and 0.03), while PLS was significantly associated with early stage and Lynch syndrome-associated multiple cancer (p=0.04 and 0.001). The trend towards favorable OS of PLS was stronger in advanced stage than in early stage (hazard ratio, 0.044 [95% CI 0-25.6] vs. 0.49 [0.063-3.8]). In the subset receiving adjuvant therapies, PLS showed trends towards favorable disease-free survival compared to sporadic by contrast with patients receiving no adjuvant therapies showing no such trend (hazard ratio, 0.045 [95% CI 0-20.3] vs. 0.81 [0.095-7.0]).
CONCLUSIONS: The current findings suggest that analyzing MMR status and searching for Lynch syndrome may identify a subset of patients with favorable survival and high sensitivity to adjuvant therapies, providing novel and useful implications for formulating the precision medicine in endometrial carcinoma.

Villacis RA, Miranda PM, Gomy I, et al.
Contribution of rare germline copy number variations and common susceptibility loci in Lynch syndrome patients negative for mutations in the mismatch repair genes.
Int J Cancer. 2016; 138(8):1928-35 [PubMed] Related Publications
In colorectal carcinoma (CRC), 35% of cases are known to have a hereditary component, while a lower proportion (∼ 5%) can be explained by known genetic factors. In this study, copy number variations (CNVs) were evaluated in 45 unrelated patients with clinical hypothesis of Lynch syndrome (Amsterdam or Bethesda criteria); negative for MLH1, MSH2, MSH6, PMS2, CHEK2*1100delC and TP53 pathogenic mutations; aiming to reveal new predisposing genes. Analyses with two different microarray platforms (Agilent 180K and Affymetrix CytoScan HD) revealed 35 rare CNVs covering 67 known genes in 22 patients. Gains (GALNT6 and GALNT11) and losses (SEMA3C) involving the same gene families related to CRC susceptibility were found among the rare CNVs. Segregation analysis performed on four relatives from one family suggested the involvement of GALNT11 and KMT2C in those at risk of developing CRC. Notably, in silico molecular analysis revealed that 61% (41/67) of the genes covered by rare CNVs were associated with cancer, mainly colorectal (17 genes). Ten common SNPs, previously associated with CRC, were genotyped in 39 index patients and 100 sporadic CRC cases. Although no significant, an increased number of risk alleles was detected in the index cases compared with the sporadic CRC patients. None of the SNPs were covered by CNVs, suggesting an independent effect of each alteration in cancer susceptibility. In conclusion, rare germline CNVs and common SNPs may contribute to an increased risk for hereditary CRC in patients with mismatch repair proficiency.

Wang Q
Cancer predisposition genes: molecular mechanisms and clinical impact on personalized cancer care: examples of Lynch and HBOC syndromes.
Acta Pharmacol Sin. 2016; 37(2):143-9 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
Up to 10% of cancers occur through the inherited mutation of a group of genes called cancer predisposition genes. Individuals who carry a mutant allele of these genes have an increased susceptibility to cancer. A growing number of cancer susceptibility genes are being identified, and the physiopathology of germline mutation-based cancer development is also being elucidated with accumulating clinical and molecular data. More importantly, the identification of familial mutations has become routine practice, which is a perfect example of bench-to-bed translational medicine. Recently, other clinical applications of predisposition genes have been exploited, especially as efficient biomarkers predicting prognosis or response to treatment. Thus, it appears interesting to give an overview of the advances and impacts of predisposition genes in personalized cancer care by taking representative and common cancer syndromes as examples: Lynch syndrome for the first example, which is related to cancer susceptibility, and breast and ovary cancer syndrome for the second example, which involves BRCA deficiency-related targeted therapy.

Eguchi H, Kumamoto K, Suzuki O, et al.
Identification of a Japanese Lynch syndrome patient with large deletion in the 3' region of the EPCAM gene.
Jpn J Clin Oncol. 2016; 46(2):178-84 [PubMed] Related Publications
Germline deletion of the 3' portion of the Epithelial Cell Adhesion Molecule (EPCAM) gene located 5' upstream of MutS Homolog 2 (MSH2) is a novel mechanism for its inactivation in Lynch syndrome. However, its contribution in Japanese Lynch syndrome patients is poorly understood. Moreover, somatic events inactivating the remaining allele of MSH2 in cancer tissue have not been elucidated in Lynch syndrome patients with such EPCAM deletions. We identified a Japanese Lynch syndrome patient with colon cancer who evidenced germline deletion of a 4130 bp fragment of EPCAM encompassing exons 8 and 9 (c.859-672_*2170del). In normal colonic mucosa, two known fusion-transcripts of EPCAM/MSH2 generated from the rearranged gene were observed and heterozygous methylation of the MSH2 gene promoter was detected. In cancer tissue, dense methylation of MSH2 was observed and MLPA analysis demonstrated somatic deletion of the remaining EPCAM allele including exon 9, indicating that somatic deletion of EPCAM is responsible for complete inactivation of MSH2.

Kastrinos F, Ojha RP, Leenen C, et al.
Comparison of Prediction Models for Lynch Syndrome Among Individuals With Colorectal Cancer.
J Natl Cancer Inst. 2016; 108(2) [PubMed] Article available free on PMC after 01/05/2017 Related Publications
BACKGROUND: Recent guidelines recommend the Lynch Syndrome prediction models MMRPredict, MMRPro, and PREMM1,2,6 for the identification of MMR gene mutation carriers. We compared the predictive performance and clinical usefulness of these prediction models to identify mutation carriers.
METHODS: Pedigree data from CRC patients in 11 North American, European, and Australian cohorts (6 clinic- and 5 population-based sites) were used to calculate predicted probabilities of pathogenic MLH1, MSH2, or MSH6 gene mutations by each model and gene-specific predictions by MMRPro and PREMM1,2,6. We examined discrimination with area under the receiver operating characteristic curve (AUC), calibration with observed to expected (O/E) ratio, and clinical usefulness using decision curve analysis to select patients for further evaluation. All statistical tests were two-sided.
RESULTS: Mutations were detected in 539 of 2304 (23%) individuals from the clinic-based cohorts (237 MLH1, 251 MSH2, 51 MSH6) and 150 of 3451 (4.4%) individuals from the population-based cohorts (47 MLH1, 71 MSH2, 32 MSH6). Discrimination was similar for clinic- and population-based cohorts: AUCs of 0.76 vs 0.77 for MMRPredict, 0.82 vs 0.85 for MMRPro, and 0.85 vs 0.88 for PREMM1,2,6. For clinic- and population-based cohorts, O/E deviated from 1 for MMRPredict (0.38 and 0.31, respectively) and MMRPro (0.62 and 0.36) but were more satisfactory for PREMM1,2,6 (1.0 and 0.70). MMRPro or PREMM1,2,6 predictions were clinically useful at thresholds of 5% or greater and in particular at greater than 15%.
CONCLUSIONS: MMRPro and PREMM1,2,6 can well be used to select CRC patients from genetics clinics or population-based settings for tumor and/or germline testing at a 5% or higher risk. If no MMR deficiency is detected and risk exceeds 15%, we suggest considering additional genetic etiologies for the cause of cancer in the family.

Goodfellow PJ, Billingsley CC, Lankes HA, et al.
Combined Microsatellite Instability, MLH1 Methylation Analysis, and Immunohistochemistry for Lynch Syndrome Screening in Endometrial Cancers From GOG210: An NRG Oncology and Gynecologic Oncology Group Study.
J Clin Oncol. 2015; 33(36):4301-8 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
PURPOSE: The best screening practice for Lynch syndrome (LS) in endometrial cancer (EC) remains unknown. We sought to determine whether tumor microsatellite instability (MSI) typing along with immunohistochemistry (IHC) and MLH1 methylation analysis can help identify women with LS.
PATIENTS AND METHODS: ECs from GOG210 patients were assessed for MSI, MLH1 methylation, and mismatch repair (MMR) protein expression. Each tumor was classified as having normal MMR, defective MMR associated with MLH1 methylation, or probable MMR mutation (ie, defective MMR but no methylation). Cancer family history and demographic and clinical features were compared for the three groups. Lynch mutation testing was performed for a subset of women.
RESULTS: Analysis of 1,002 ECs suggested possible MMR mutation in 11.8% of tumors. The number of patients with a family history suggestive of LS was highest among women whose tumors were classified as probable MMR mutation (P = .001). Lynch mutations were identified in 41% of patient cases classified as probable mutation (21 of 51 tested). One of the MSH6 Lynch mutations was identified in a patient whose tumor had intact MSH6 expression. Age at diagnosis was younger for mutation carriers than noncarriers (54.3 v 62.3 years; P < .01), with five carriers diagnosed at age > 60 years.
CONCLUSION: Combined MSI, methylation, and IHC analysis may prove useful in Lynch screening in EC. Twenty-four percent of mutation carriers presented with ECs at age > 60 years, and one carrier had an MSI-positive tumor with no IHC defect. Restricting Lynch testing to women diagnosed at age < 60 years or to women with IHC defects could result in missing a substantial fraction of genetic disease.

Baris HN, Barnes-Kedar I, Toledano H, et al.
Constitutional Mismatch Repair Deficiency in Israel: High Proportion of Founder Mutations in MMR Genes and Consanguinity.
Pediatr Blood Cancer. 2016; 63(3):418-27 [PubMed] Related Publications
BACKGROUND: Heterozygous germline mutations in any of the mismatch repair (MMR) genes, MLH1, MSH2, MSH6, and PMS2, cause Lynch syndrome (LS), an autosomal dominant cancer predisposition syndrome conferring a high risk of colorectal, endometrial, and other cancers in adulthood. Offspring of couples where both spouses have LS have a 1:4 risk of inheriting biallelic MMR gene mutations. These cause constitutional MMR deficiency (CMMRD) syndrome, a severe recessively inherited cancer syndrome with a broad tumor spectrum including mainly hematological malignancies, brain tumors, and colon cancer in childhood and adolescence. Many CMMRD children also present with café au lait spots and axillary freckling mimicking neurofibromatosis type 1.
PROCEDURE: We describe our experience in seven CMMRD families demonstrating the role and importance of founder mutations and consanguinity on its prevalence. Clinical presentations included brain tumors, colon cancer, lymphoma, and small bowel cancer.
RESULTS: In children from two nonconsanguineous Ashkenazi Jewish (AJ) families, the common Ashkenazi founder mutations were detected; these were homozygous in one family and compound heterozygous in the other. In four consanguineous families of various ancestries, different homozygous mutations were identified. In a nonconsanguineous Caucasus/AJ family, lack of PMS2 was demonstrated in tumor and normal tissues; however, mutations were not identified.
CONCLUSIONS: CMMRD is rare, but, especially in areas where founder mutations for LS and consanguinity are common, pediatricians should be aware of it since they are the first to encounter these children. Early diagnosis will enable tailored cancer surveillance in the entire family and a discussion regarding prenatal genetic diagnosis.

Further References

Lynch HT, Lynch PM
The cancer-family syndrome: a pragmatic basis for syndrome identification.
Dis Colon Rectum. 1979; 22(2):106-10 [PubMed] Related Publications
We report a family manifesting the cancer-family syndrome in which 11 family members had colonic carcinomas (predominantly involving the proximal colon, in the absence of polyposis), with an average age at onset of 35 years. Three women had endometrial or endocervical cancers. The kindred is notable in that its full evaluation was predicated upon the recognition of features consistent with the cancer-family syndrome in only two sisters. The ascertainment and evaluation of the kindred demonstrates the clinical utility of regarding such criteria (early cancer onset, multiple primary cancers, proximal colonic involvement) as a basis for selecting cases for more thorough family-history evaluation. Although such selection criteria are not pathognomonic for the syndrome, identification of a more extensive family cancer history sometimes enables the initiation of a highly specific cancer surveillance program. Specific attention has been given to the problems of screening patients at risk for the development of proximal colonic cancer, an important feature of the cancer-family syndrome. Innovative operative management is also indicated, such as total colectomy for initial colonic cancer, and consideration of prophylactic hysterectomy for women with colonic cancer (because of the high risk of development of endometrial carcinoma).

Lynch HT, Lynch J
Lynch syndrome: genetics, natural history, genetic counseling, and prevention.
J Clin Oncol. 2000; 18(21 Suppl):19S-31S [PubMed] Related Publications
Lynch syndrome is the most common hereditary form of colorectal cancer (CRC). Its natural history has been investigated extensively, so that highly targeted surveillance and management strategies, melded to its natural history, have proven effective in cancer control. Most important is the early age of onset of cancer (approximately 44 years), involving CRC and the several extracolonic cancers that are integral to the syndrome. With respect to CRC, approximately 70% of cases occur proximal to the splenic flexure. Synchronous and metachronous CRCs are extremely common. Full colonoscopy should be initiated when the patient is between the ages of 20 and 25, and because of the accelerated carcinogenesis of CRC, it should be performed every 1 to 2 years. The presence of initial CRC requires subtotal colectomy, given the mentioned increased frequency of metachronous cancer. Options available for germ-line mutation carriers, in addition to cancer screening, include prophylactic colectomy as well as prophylactic total abdominal hysterectomy and bilateral salpingo-oophorectomy. The discovery of mismatch repair germ-line mutations (most commonly MSH2 or MLH1) has added significantly to the recognition of this disease as well as to the search for high-risk individuals throughout families who, with genetic counseling, may become candidates for germ-line mutation testing. Clearly, hereditary nonpolyposis colorectal cancer provides an excellent opportunity for learning about the etio-pathogenesis of cancer at the molecular and clinical levels and how this knowledge might ultimately be exploited for cancer control. A search for chemoprevention agents, such as cyclo-oxygenase 2 inhibitors, as well as for putative environmental effects and how they may interact with the genetic component in CRC etiology should abet this entire cancer control process.

Lynch HT, Lynch JF
Hereditary nonpolyposis colorectal cancer.
Semin Surg Oncol. 2000; 18(4):305-13 [PubMed] Related Publications
Hereditary nonpolyposis colorectal cancer (HNPCC), or Lynch syndrome, is the most common form of hereditary colorectal cancer (CRC). A well-orchestrated cancer family history is essential for its diagnosis since, unlike its familial adenomatous polyposis (FAP) hereditary cancer counterpart, HNPCC lacks distinguishing clinical stigmata of its cancer genetic risk. Discoveries in the 1990s of germ-line mutations, the most common of which are hMSH2 and hMLH1, have added enormous power to the diagnosis of Lynch syndrome. Its medical management is contingent upon its natural history. For example, approximately 70% of CRCs occur proximal to the splenic flexure, with one-third of the cancers occurring in the cecum, thereby mandating full colonoscopy. A high rate of metachronous CRCs indicates the need for no less than a subtotal colectomy for the management of initial CRC. Genetic counseling is essential prior to DNA testing, and at the time of disclosure of the results. Education of patients as well as physicians about all facets of this disorder is extremely important. If patients are to show compliance with germ-line testing, screening, and management options, they must understand the natural history and the significance of their genetic risk status. Physicians must also be aware of clinical nuances of this disorder to provide the necessary care.

Liu B, Parsons R, Papadopoulos N, et al.
Analysis of mismatch repair genes in hereditary non-polyposis colorectal cancer patients.
Nat Med. 1996; 2(2):169-74 [PubMed] Related Publications
Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant disorder characterized by the early onset of colorectal cancer and linked to germline defects in at least four mismatch repair genes. Although much has been learned about the molecular pathogenesis of this disease, questions related to effective presymptomatic diagnosis are largely unanswered because of its genetic complexity. In this study, we evaluated tumors from 74 HNPCC kindreds for genomic instability characteristic of a mismatch repair deficiency and found such instability in 92% of the kindreds. The entire coding regions of the five known human mismatch repair genes were evaluated in 48 kindreds with instability, and mutations were identified in 70%. This study demonstrates that a combination of techniques can be used to genetically diagnose tumor susceptibility in the majority of HNPCC kindreds and lays the foundation for genetic testing of this relatively common disease.

Wang Q, Lasset C, Desseigne F, et al.
Prevalence of germline mutations of hMLH1, hMSH2, hPMS1, hPMS2, and hMSH6 genes in 75 French kindreds with nonpolyposis colorectal cancer.
Hum Genet. 1999 Jul-Aug; 105(1-2):79-85 [PubMed] Related Publications
Hereditary nonpolyposis colorectal cancer (HNPCC) is a syndrome characterized by familial predisposition to colorectal carcinoma and extracolonic cancers of the gastrointestinal, urological, and female reproductive tracts. This dominant disorder is caused by germline defects in one of at least five DNA mismatch repair (MMR) genes: hMLH1, hMSH2, hPMS1, hPMS2, and hMSH6 (GTBP). Germline mutations of hMSH2 and hMLH1 are also frequently identified in families not fulfilling all the Amsterdam criteria, thereby demonstrating that the involvement of these genes is not confined to typical HNPCC. To evaluate the respective involvement of the various MMR genes in typical and incomplete HNPCC syndromes, we have performed an analysis of the hMLH1, hMSH2, hPMS1, hPMS2, and hMSH6 genes in a large series of French kindreds (n=75) with colorectal tumors and/or aggregation of extracolonic cancers belonging to the HNPCC spectrum. Mutational analysis has been performed in all families, without preselection for the tumor phenotype. We have detected 26 pathogenic germline mutations of the hMLH1 and hMSH2 genes and several novel variants of the hPMS1, hPMS2, and hMSH6 genes. Our data confirm that, regardless of the type of families and the tumor phenotype, hPMS1, hPMS2, and hMSH6 germline mutations are rare in familial aggregation of colorectal cancers. Furthermore, they suggest that the presence of multiple primary malignancies in a single individual and the observation of extracolonic tumors in relatives of a colorectal cancer patient should be included among the guidelines for referring patients for genetic testing.

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