Lynch Syndrome - HNPCC


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

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Tag cloud generated 08 August, 2015 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'.

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

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

Latest Publications

Sana A, Farid Z, Amel M, et al.
[Molecular characterization of Lynch syndrome in Tunisia].
Tunis Med. 2014; 92(7):458-62 [PubMed] Related Publications
BACKGROUND: High rates of early colorectal cancers (CRC) are observed in Tunisia suggesting genetic susceptibility. Nevertheless, up to now no molecular studies have been performed in the Tunisian population.
AIM: To evaluate the clinical and genetic characteristics of Tunisian families suspected of hereditary nonpolyposis colorectal cancer (HNPCC) and to identify new tumoral markers for CRC susceptibility leading to distinguish patients with sporadic CRC from those with familial CRC, like HNPCC.
METHODS: 31 unrelated families suspected of HNPCC were screened for germline mutations in MMR genes. We have also analyzed tumoral phenotype and the genetic characteristics of tumors from 51 patients with CRC meeting the Bethesda criteria.
RESULTS: 10 different germ line mutations, 8 of which were novel, were identified in 11 out of the 31 families (35.5%), 5 in MSH2 and 5 in MLH1. Our results showed that MUC5AC expression was more frequent in patients with family history of CRC (p=0.039).
CONCLUSION: The analysis of MUC5AC expression might be very beneficial in the detection of Tunisian patients with high susceptibility to CRC.

Cini G, Carnevali I, Quaia M, et al.
Concomitant mutation and epimutation of the MLH1 gene in a Lynch syndrome family.
Carcinogenesis. 2015; 36(4):452-8 [PubMed] Related Publications
Lynch syndrome (LS) is an inherited predisposition cancer syndrome, typically caused by germline mutations in the mismatch repair genes MLH1, MSH2, MSH6 and PMS2. In the last years, a role for epimutations of the same genes has also been reported. MLH1 promoter methylation is a well known mechanism of somatic inactivation in tumors, and more recently, several cases of constitutional methylation have been identified. In four subjects affected by multiple tumors and belonging to a suspected LS family, we detected a novel secondary MLH1 gene epimutation. The methylation of MLH1 promoter was always linked in cis with a 997 bp-deletion (c.-168_c.116+713del), that removed exon 1 and partially involved the promoter of the same gene. Differently from cases with constitutional primary MLH1 inactivation, this secondary methylation was allele-specific and CpGs of the residual promoter region were totally methylated, leading to complete allele silencing. In the colon tumor of the proband, MLH1 and PMS2 expression was completely lost as a consequence of a pathogenic somatic point mutation (MLH1 c.199G>A, p.Gly67Arg) that also abrogated local methylation by destroying a CpG site. The evidences obtained highlight how MLH1 mutations and epimutations can reciprocally influence each other and suggest that an altered structure of the MLH1 locus results in epigenetic alteration.

Syngal S, Brand RE, Church JM, et al.
ACG clinical guideline: Genetic testing and management of hereditary gastrointestinal cancer syndromes.
Am J Gastroenterol. 2015; 110(2):223-62; quiz 263 [PubMed] Related Publications
This guideline presents recommendations for the management of patients with hereditary gastrointestinal cancer syndromes. The initial assessment is the collection of a family history of cancers and premalignant gastrointestinal conditions and should provide enough information to develop a preliminary determination of the risk of a familial predisposition to cancer. Age at diagnosis and lineage (maternal and/or paternal) should be documented for all diagnoses, especially in first- and second-degree relatives. When indicated, genetic testing for a germline mutation should be done on the most informative candidate(s) identified through the family history evaluation and/or tumor analysis to confirm a diagnosis and allow for predictive testing of at-risk relatives. Genetic testing should be conducted in the context of pre- and post-test genetic counseling to ensure the patient's informed decision making. Patients who meet clinical criteria for a syndrome as well as those with identified pathogenic germline mutations should receive appropriate surveillance measures in order to minimize their overall risk of developing syndrome-specific cancers. This guideline specifically discusses genetic testing and management of Lynch syndrome, familial adenomatous polyposis (FAP), attenuated familial adenomatous polyposis (AFAP), MUTYH-associated polyposis (MAP), Peutz-Jeghers syndrome, juvenile polyposis syndrome, Cowden syndrome, serrated (hyperplastic) polyposis syndrome, hereditary pancreatic cancer, and hereditary gastric cancer.

Moreira L, Muñoz J, Cuatrecasas M, et al.
Prevalence of somatic mutl homolog 1 promoter hypermethylation in Lynch syndrome colorectal cancer.
Cancer. 2015; 121(9):1395-404 [PubMed] Related Publications
BACKGROUND: Colorectal cancers (CRCs) that have microsatellite instability (MSI) and mutL homolog 1 (MLH1) immunoloss are observed in 3 clinical scenarios: Lynch syndrome (LS), sporadic MSI CRC, and Lynch-like syndrome (LLS). v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) mutational analysis is used to differentiate LS from sporadic MSI CRC. The role of MLH1 promoter methylation status for the differential diagnosis of these clinical forms is not well established. The objectives of this study were: 1) to analyze MLH1 promoter methylation in MLH1-deficient CRCs by pyrosequencing, and 2) to assess its role in the differential diagnosis of MLH1-deficient CRCs.
METHODS: In total, 165 CRCs were analyzed, including LS (n = 19), MSI BRAF-mutated CRC (n = 37), MSI BRAF wild-type CRC (n = 60), and a control group of CRCs without MSI (microsatellite stable [MSS] CRC; n = 49). MLH1 promoter methylation status was analyzed by pyrosequencing, and the ability of different strategies to identify LS was assessed.
RESULTS: The average ± standard deviation methylation in LS (9% ± 7%) was significantly lower than that in MSI BRAF-mutated CRC (42% ± 17%; P < .001) and in MSI BRAF wild-type CRC (25% ± 19%; P = .002). Somatic MLH1 hypermethylation was detected in 3 patients (15.8%) with LS, in 34 patients (91.9%) with MSI BRAF-mutated CRC, and in 37 patients (61.7%) with MSI BRAF wild-type tumors. Patients with MSI BRAF wild-type, unmethylated tumors (ie, LLS) had a stronger family history of CRC than those who had tumors with MLH1 methylation (P < .05). The sensitivity for ruling out LS was 100% for BRAF analysis, 84.2% for MLH1 methylation analysis, and 84.2% for the combination of both analyses.
CONCLUSIONS: Somatic MLH1 promoter methylation occurs in up to 15% of LS CRCs. Somatic BRAF analysis is the most sensitive strategy for ruling out LS. Patients who have CRCs with loss of MLH1 protein expression and neither BRAF mutation nor MLH1 methylation resemble patients with LS.

Jenkins MA, Dowty JG, Ait Ouakrim D, et al.
Short-term risk of colorectal cancer in individuals with lynch syndrome: a meta-analysis.
J Clin Oncol. 2015; 33(4):326-31 [PubMed] Related Publications
PURPOSE: For carriers of germline mutations in DNA mismatch repair genes, the most relevant statistic for cancer prevention is colorectal cancer (Lynch syndrome) risk, particularly in the short term.
METHODS: We conducted a meta-analysis of all independent published Lynch syndrome studies reporting age- and sex-dependent colorectal cancer risks. We estimated 5-year colorectal cancer risk over different age groups, separately for male and female mutation carriers, and number needed to screen to prevent one death.
RESULTS: We pooled estimates from analyses of 1,114 Lynch syndrome families (508 with MLH1 mutations and 606 with MSH2 mutations). On average, one in 71 male and one in 102 female MLH1 or MSH2 mutation carriers in their 20s will be diagnosed with colorectal cancer in the next 5 years. These colorectal cancer risks increase with age, peaking in the 50s (one in seven males and one in 12 females), and then decrease with age (one in 13 males and one in 19 females in their 70s). Annual colonoscopy in 16 males or 25 females in their 50s would prevent one death from colorectal cancer over 5 years while resulting in almost no serious complications. In comparison, annual colonoscopy in 155 males or 217 females in their 20s would prevent one death while resulting in approximately one serious complication.
CONCLUSION: For MLH1 or MSH2 mutation carriers, current guidelines recommend colonoscopy every 1 to 2 years starting in their 20s. Our findings support this regimen from age 30 years; however, it might not be justifiable for carriers who are in their 20s.

Xiong HY, Alipanahi B, Lee LJ, et al.
RNA splicing. The human splicing code reveals new insights into the genetic determinants of disease.
Science. 2015; 347(6218):1254806 [PubMed] Article available free on PMC after 09/01/2016 Related Publications
To facilitate precision medicine and whole-genome annotation, we developed a machine-learning technique that scores how strongly genetic variants affect RNA splicing, whose alteration contributes to many diseases. Analysis of more than 650,000 intronic and exonic variants revealed widespread patterns of mutation-driven aberrant splicing. Intronic disease mutations that are more than 30 nucleotides from any splice site alter splicing nine times as often as common variants, and missense exonic disease mutations that have the least impact on protein function are five times as likely as others to alter splicing. We detected tens of thousands of disease-causing mutations, including those involved in cancers and spinal muscular atrophy. Examination of intronic and exonic variants found using whole-genome sequencing of individuals with autism revealed misspliced genes with neurodevelopmental phenotypes. Our approach provides evidence for causal variants and should enable new discoveries in precision medicine.

ten Broeke SW, Brohet RM, Tops CM, et al.
Lynch syndrome caused by germline PMS2 mutations: delineating the cancer risk.
J Clin Oncol. 2015; 33(4):319-25 [PubMed] Related Publications
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.

Saam J, Moyes K, Landon M, et al.
Hereditary cancer-associated mutations in women diagnosed with two primary cancers: an opportunity to identify hereditary cancer syndromes after the first cancer diagnosis.
Oncology. 2015; 88(4):226-33 [PubMed] Related Publications
OBJECTIVES: Patients with hereditary cancer syndromes are at high risk for a second primary cancer. Early identification of these patients after an initial cancer diagnosis is the key to implementing cancer risk-reducing strategies.
METHODS: A commercial laboratory database was searched for women with a history of both breast and ovarian or colorectal and endometrial cancer who underwent genetic testing for hereditary breast and ovarian cancer (HBOC) or Lynch syndrome (LS).
RESULTS: Among women with both breast and ovarian cancer, 22.4% (2,237/9,982) had a BRCA1 or BRCA2 mutation. Among women with both colorectal and ovarian cancer, 28.1% (264/941) had a mutation associated with LS. In 66.6% of BRCA1 or BRCA2 mutation carriers and in 58.3% of LS mutation carriers, >5 years passed between the cancer diagnoses. Of patients with HBOC and LS, 56 and 65.2%, respectively, met the National Comprehensive Cancer Network guidelines for hereditary cancer testing after their initial diagnosis based on their personal cancer history alone.
CONCLUSIONS: A substantial number of women tested for LS or HBOC after being diagnosed with two successive primary cancers were diagnosed with a hereditary cancer syndrome. In many cases, the time interval between the diagnoses was long enough to allow for the implementation of surveillance and/or prophylactic measures.

Hinrichsen I, Schäfer D, Langer D, et al.
Functional testing strategy for coding genetic variants of unclear significance in MLH1 in Lynch syndrome diagnosis.
Carcinogenesis. 2015; 36(2):202-11 [PubMed] Related Publications
Lynch syndrome is caused by inactivating mutations in the MLH1 gene, but genetic variants of unclear significance frequently preclude diagnosis. Functional testing can reveal variant-conferred defects in gene or protein function. Based on functional defect frequencies and clinical applicability of test systems, we developed a functional testing strategy aimed at efficiently detecting pathogenic defects in coding MLH1 variants. In this strategy, tests of repair activity and expression are prioritized over analyses of subcellular protein localization and messenger RNA (mRNA) formation. This strategy was used for four unclear coding MLH1 variants (p.Asp41His, p.Leu507Phe, p.Gln689Arg, p.Glu605del + p.Val716Met). Expression was analyzed using a transfection system, mismatch repair (MMR) activity by complementation in vitro, mRNA formation by reverse transcriptase-PCR in carrier lymphocyte mRNA, and subcellular localization with dye-labeled fusion constructs. All tests included clinically meaningful controls. The strategy enabled efficient identification of defects in two unclear variants: the p.Asp41His variant showed loss of MMR activity, whereas the compound variant p.Glu605del + p.Val716Met had a defect of expression. This expression defect was significantly stronger than the pathogenic expression reference variant analyzed in parallel, therefore the defect of the compound variant is also pathogenic. Interestingly, the expression defect was caused additively by both of the compound variants, at least one of which is non-pathogenic when occurring by itself. Tests were neutral for p.Leu507Phe and p.Gln689Arg, and the results were consistent with available clinical data. We finally discuss the improved sensitivity and efficiency of the applied strategy and its limitations in analyzing unclear coding MLH1 variants.

Crucianelli F, Tricarico R, Turchetti D, et al.
MLH1 constitutional and somatic methylation in patients with MLH1 negative tumors fulfilling the revised Bethesda criteria.
Epigenetics. 2014; 9(10):1431-8 [PubMed] Related Publications
Lynch syndrome (LS) is a tumor predisposing condition caused by constitutional defects in genes coding for components of the mismatch repair (MMR) apparatus. While hypermethylation of the promoter of the MMR gene MLH1 occurs in about 15% of colorectal cancer samples, it has also been observed as a constitutional alteration, in the absence of DNA sequence mutations, in a small number of LS patients. In order to obtain further insights on the phenotypic characteristics of MLH1 epimutation carriers, we investigated the somatic and constitutional MLH1 methylation status of 14 unrelated subjects with a suspicion of LS who were negative for MMR gene constitutional mutations and whose tumors did not express the MLH1 protein. A novel case of constitutional MLH1 epimutation was identified. This patient was affected with multiple primary tumors, including breast cancer, diagnosed starting from the age of 55 y. Investigation of her offspring by allele specific expression revealed that the epimutation was not stable across generations. We also found MLH1 hypermethylation in cancer samples from 4 additional patients who did not have evidence of constitutional defects. These patients had some characteristics of LS, namely early age at onset and/or positive family history, raising the possibility of genetic influences in the establishment of somatic MLH1 methylation.

Vilar E, Mork ME, Cuddy A, et al.
Role of microsatellite instability-low as a diagnostic biomarker of Lynch syndrome in colorectal cancer.
Cancer Genet. 2014 Oct-Dec; 207(10-12):495-502 [PubMed] Article available free on PMC after 13/10/2015 Related Publications
Lynch syndrome is the most common Mendelian disorder predisposing persons to hereditary colorectal cancer. Carriers of MSH6 mutations constitute less than 10% of the total of cases with Lynch syndrome and present with a weaker clinical phenotype, including low levels of microsatellite instability (MSI-L) in colorectal tumors. The frequency of MSH6 mutation carriers among patients presenting with MSI-L colorectal cancer has yet to be determined, as has the appropriate genetic workup in this context. We have reviewed here the clinicopathologic characteristics, immunohistochemistry, and genetic testing results for 71 patients at a single institution diagnosed with MSI-L colorectal cancers. Of 71 patients with MSI-L tumors, 21 underwent genetic testing for MSH6 mutations, three of whom presented with loss of staining of MSH6 and only one of whom carried a pathogenic germline MSH6 mutation in exon 4 (c.2677_2678delCT; p.Leu893Alafs*6). This latter patient had a significant family history of cancer and had a rectal primary tumor that showed instability only in mononucleotide markers. In this cohort of MSI-L patients, we detected no notable clinicopathologic or molecular characteristic that would help to distinguish a group most likely to harbor germline MSH6 mutations. Therefore, we conclude that the prevalence of MSH6 mutations among patients with MSI-L tumors is very low. Microsatellite instability analysis combined with immunohistochemistry of mismatch repair proteins adequately detects potential MSH6 mutation carriers among MSI-L colorectal cancers.

Taber JM, Chang CQ, Lam TK, et al.
Prevalence and correlates of receiving and sharing high-penetrance cancer genetic test results: findings from the Health Information National Trends Survey.
Public Health Genomics. 2015; 18(2):67-77 [PubMed] Article available free on PMC after 01/01/2016 Related Publications
BACKGROUND/AIMS: The aim of this study was to explore the prevalence and correlates of receiving and sharing high-penetrance cancer genetic test results.
METHODS: Participants completed the population-based, cross-sectional 2013 Health Information National Trends Survey. We examined sociodemographic characteristics of participants reporting having had BRCA1/2 or Lynch syndrome genetic testing, and sociodemographic and psychosocial correlates of sharing test results with health professionals and family members.
RESULTS: Participants who underwent BRCA1/2 or Lynch syndrome genetic testing (n = 77; 2.42% of respondents) were more likely to be female and to have a family or personal history of cancer than those not undergoing testing. Approximately three-quarters of participants shared results with health professionals and three-quarters with their family; only 4% did not share results with anyone. Participants who shared results with health professionals reported greater optimism, self-efficacy for health management, and trust in information from their doctors. Participants who shared results with their family were more likely to be female and to have a personal history of cancer, and had greater self-efficacy for health management, perceived less ambiguity in cancer prevention recommendations, and lower cancer prevention fatalism.
CONCLUSIONS: We identified several novel psychosocial correlates of sharing genetic information. Health professionals may use this information to identify patients less likely to share information with at-risk family members.

Bhaijee F, Brown AS
Muir-Torre syndrome.
Arch Pathol Lab Med. 2014; 138(12):1685-9 [PubMed] Related Publications
Muir-Torre syndrome (MTS) is a rare autosomal-dominant genodermatosis characterized by sebaceous neoplasms and one or more visceral malignancies. Sebaceous tumors include sebaceous adenoma and carcinoma, which may be solitary or multiple. Visceral malignancies most often arise in the colorectum and endometrium. Because a subset of patients with phenotypic MTS will have germline mutations in the DNA mismatch repair genes hMSH2 and hMLH1, MTS is considered a phenotypic subtype of Lynch syndrome (also known as hereditary nonpolyposis colorectal cancer syndrome), in which inherited defects in DNA mismatch repair genes result in microsatellite instability. Pathologists have an important role in the early detection and initial diagnosis of MTS: identification of at-risk individuals allows appropriate screening and surveillance for visceral malignancies, thereby reducing morbidity and mortality. Herein, we describe the clinicopathologic features of MTS.

Newton K, Jorgensen NM, Wallace AJ, et al.
Tumour MLH1 promoter region methylation testing is an effective prescreen for Lynch Syndrome (HNPCC).
J Med Genet. 2014; 51(12):789-96 [PubMed] Related Publications
BACKGROUND AND AIMS: Lynch syndrome (LS) patients have DNA mismatch repair deficiency and up to 80% lifetime risk of colorectal cancer (CRC). Screening of mutation carriers reduces CRC incidence and mortality. Selection for constitutional mutation testing relies on family history (Amsterdam and Bethesda Guidelines) and tumour-derived biomarkers. Initial biomarker analysis uses mismatch repair protein immunohistochemistry and microsatellite instability. Abnormalities in either identify mismatch repair deficiency but do not differentiate sporadic epigenetic defects, due to MLH1 promoter region methylation (13% of CRCs) from LS (4% of CRCs). A diagnostic biomarker capable of making this distinction would be valuable. This study compared two biomarkers in tumours with mismatch repair deficiency; quantification of methylation of the MLH1 promoter region using a novel assay and BRAF c.1799T>A, p.(Val600Glu) mutation status in the identification of constitutional mutations.
METHODS: Tumour DNA was extracted (formalin fixed, paraffin embedded, FFPE tissue) and pyrosequencing used to test for MLH1 promoter methylation and presence of the BRAF c.1799T>A, p.(Val600Glu) mutation 71 CRCs from individuals with pathogenic MLH1 mutations and 73 CRCs with sporadic MLH1 loss. Specificity and sensitivity was compared.
FINDINGSS: Unmethylated MLH1 promoter: sensitivity 94.4% (95% CI 86.2% to 98.4%), specificity 87.7% (95% CI 77.9% to 94.2%), Wild-type BRAF (codon 600): sensitivity 65.8% (95% CI 53.7% to 76.5%), specificity 98.6% (95% CI 92.4% to 100.0%) for the identification of those with pathogenic MLH1 mutations.
CONCLUSIONS: Quantitative MLH1 promoter region methylation using pyrosequencing is superior to BRAF codon 600 mutation status in identifying constitutional mutations in mismatch repair deficient tumours.

Billingsley CC, Cohn DE, Mutch DG, et al.
Polymerase ɛ (POLE) mutations in endometrial cancer: clinical outcomes and implications for Lynch syndrome testing.
Cancer. 2015; 121(3):386-94 [PubMed] Article available free on PMC after 01/02/2016 Related Publications
BACKGROUND: DNA polymerase ɛ (POLE) exonuclease domain mutations characterize a subtype of endometrial cancer (EC) with a markedly increased somatic mutational burden. POLE-mutant tumors were described as a molecular subtype with improved progression-free survival by The Cancer Genome Atlas. In this study, the frequency, spectrum, prognostic significance, and potential clinical application of POLE mutations were investigated in patients with endometrioid EC.
METHODS: Polymerase chain reaction amplification and Sanger sequencing were used to test for POLE mutations in 544 tumors. Correlations between demographic, survival, clinicopathologic, and molecular features were investigated. Statistical tests were 2-sided.
RESULTS: Thirty POLE mutations (5.6%) were identified. Mutations were associated with younger age (<60 years; P=.001). POLE mutations were detected in tumors with microsatellite stability (MSS) and microsatellite instability (MSI) at similar frequencies (5.9% and 5.2%, respectively) and were most common in tumors with MSI that lacked mutL homolog 1 (MLH1) methylation (P<.001). There was no association with progression-free survival (hazard ratio, 0.22; P=.127).
CONCLUSIONS: The discovery that mutations occur with equal frequency in MSS and MSI tumors and are most frequent in MSI tumors lacking MLH1 methylation has implications for Lynch syndrome screening and mutation testing. The current results indicate that POLE mutations are associated with somatic mutation in DNA mismatch repair genes in a subset of tumors. The absence of an association between POLE mutation and progression-free survival indicates that POLE mutation status is unlikely to be a clinically useful prognostic marker. However, POLE testing in MSI ECs could serve as a marker of somatic disease origin. Therefore, POLE tumor testing may be a valuable exclusionary criterion for Lynch syndrome gene testing.

Cavallaro A, Russo A, Catania VE, et al.
Molecular screening in Sicilian families with hereditary non-poliposis colorectal cancer (H.N.P.C.C.) syndrome: identification of a novel mutation in MSH2 gene.
Int J Surg. 2014; 12 Suppl 2:S120-4 [PubMed] Related Publications
HNPCC is an autosomal inherited cancer syndrome characterized by germinal and somatic mutations of DNA mismatch repair (MMR) genes. The inherited mutation in one allele together with an acquired defect in the other allele of an MMR gene leads to accelerate tumor progression. In this study we analyzed a cohort of 11 subjects belonging to four Sicilian families with HNPCC suspected by molecular analysis of coding regions of hMSH2 (NC_000002) and hMLH1 (NC_000003) genes. Molecular analysis has detected the presence of two mutations in gene MSH2 and one mutation in MHL1 gene. In addition, we found a novel mutation consisting in a G deletion at 914 codon of the exon 16 in the MSH2 gene. This deletion leads to a stop codon due to a frame-shift, resulting in a truncated protein. We extended genetic analysis to the other family members and the same mutation was detected in three sisters and in one of the two healthy daughters. This mutation is correlated with clinical findings revealed in genealogic tree and it represents a novel mutation responsible of HNPCC.

Svec J, Schwarzová L, Janošíková B, et al.
Synchronous gastric and sebaceous cancers, a rare manifestation of MLH1-related Muir-Torre syndrome.
Int J Clin Exp Pathol. 2014; 7(8):5196-202 [PubMed] Article available free on PMC after 01/02/2016 Related Publications
Muir-Torre syndrome (MTS), a rare variant of the hereditary non polyposis colorectal cancer syndrome, is an autosomal dominant genodermatosis characterised by coincidence of sebaceous gland neoplasms (sebaceous adenoma, epithelioma, or carcinoma) and at least one internal malignancy. The underlying cause of MTS is a germline mutation in DNA mismatch repair genes MSH2, MLH1 and MSH6. We report the case of a 52-year-old caucasian woman with the development of metachronous colon cancer at the age of 38 years, uterine cancer at the age of 43 years, and unique occurrence of synchronous gastric and sebaceous carcinomas related to germline point mutation c. 2194A>T in the last exon of MLH1 gene, resulting in truncated protein in C-terminal region p. Lys732X due to premature stop codon. This mutation, not previously reported in MTS, disrupts the function of MutL complexes presumably by preventing the interaction with PMS1/PMS2 and impairing the endonuclease active site. This case points out the importance of sebaceous neoplasia, especially sebaceous adenocarcinoma, as cutaneous markers of MTS for timely implementation of cancer screening programs.

Haraldsdottir S, Hampel H, Tomsic J, et al.
Colon and endometrial cancers with mismatch repair deficiency can arise from somatic, rather than germline, mutations.
Gastroenterology. 2014; 147(6):1308-1316.e1 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
BACKGROUND & AIMS: Patients with Lynch syndrome carry germline mutations in single alleles of genes encoding the mismatch repair (MMR) proteins MLH1, MSH2, MSH6, and PMS2; when the second allele becomes mutated, cancer can develop. Increased screening for Lynch syndrome has identified patients with tumors that have deficiency in MMR, but no germline mutations in genes encoding MMR proteins. We investigated whether tumors with deficient MMR had acquired somatic mutations in patients without germline mutations in MMR genes using next-generation sequencing.
METHODS: We analyzed blood and tumor samples from 32 patients with colorectal or endometrial cancer who participated in Lynch syndrome screening studies in Ohio and were found to have tumors with MMR deficiency (based on microsatellite instability and/or absence of MMR proteins in immunohistochemical analysis, without hypermethylation of MLH1), but no germline mutations in MMR genes. Tumor DNA was sequenced for MLH1, MSH2, MSH6, PMS2, EPCAM, POLE, and POLD1 with ColoSeq and mutation frequencies were established.
RESULTS: Twenty-two of 32 patients (69%) were found to have 2 somatic (tumor) mutations in MMR genes encoding proteins that were lost from tumor samples, based on immunohistochemistry. Of the 10 remaining tumors 3 had one somatic mutation in a MMR gene, with possible loss of heterozygosity that could lead to MMR deficiency, 6 were found to be false-positive results (19%), and 1 had only one mutation in a MMR gene and remained unexplained. All of the tumors found to have somatic MMR mutations were of the hypermutated phenotype (>12 mutations/megabase); 6 had mutation frequencies >200/megabase, and 5 of these had somatic mutations in POLE, which encodes a DNA polymerase.
CONCLUSIONS: Some patients are found to have tumors with MMR defects during screening for Lynch syndrome, yet have no identifiable germline mutations in MMR genes. We found that almost 70% of these patients acquire somatic mutations in MMR genes, leading to a hypermutated phenotype of tumor cells. Patients with colon or endometrial cancers with MMR deficiency not explained by germline mutations might undergo analysis for tumor mutations in MMR genes to guide future surveillance guidelines.

Geurts-Giele WR, Leenen CH, Dubbink HJ, et al.
Somatic aberrations of mismatch repair genes as a cause of microsatellite-unstable cancers.
J Pathol. 2014; 234(4):548-59 [PubMed] Related Publications
Lynch syndrome (LS) is caused by germline mutations in mismatch repair (MMR) genes, resulting in microsatellite-unstable tumours. Approximately 35% of suspected LS (sLS) patients test negative for germline MMR gene mutations, hampering conclusive LS diagnosis. The aim of this study was to investigate somatic MMR gene aberrations in microsatellite-unstable colorectal and endometrial cancers of sLS patients negative for germline MMR gene mutations. Suspected LS cases were selected from a retrospective Clinical Genetics Department diagnostic cohort and from a prospective multicentre population-based study on LS in The Netherlands. In total, microsatellite-unstable tumours of 40 sLS patients (male/female 20/20, median age 57 years) were screened for somatic MMR gene mutations by next-generation sequencing. In addition, loss of heterozygosity (LOH) of the affected MMR genes in these tumours as well as in 68 LS-associated tumours and 27 microsatellite-unstable tumours with MLH1 promoter hypermethylation was studied. Of the sLS cases, 5/40 (13%) tumours had two pathogenic somatic mutations and 16/40 (40%) tumours had a (likely) pathogenic mutation and LOH. Overall, LOH of the affected MMR gene locus was observed in 24/39 (62%) tumours with informative LOH markers. Of the LS cases and the tumours with MLH1 promoter hypermethylation, 39/61 (64%) and 2/21 (10%) tumours, respectively, demonstrated LOH. Half of microsatellite-unstable tumours of sLS patients without germline MMR gene mutations had two (likely) deleterious somatic MMR gene aberrations, indicating their sporadic origin. Therefore, we advocate adding somatic mutation and LOH analysis of the MMR genes to the molecular diagnostic workflow of LS.

Kang SY, Park CK, Chang DK, et al.
Lynch-like syndrome: characterization and comparison with EPCAM deletion carriers.
Int J Cancer. 2015; 136(7):1568-78 [PubMed] Related Publications
Colorectal cancers (CRCs) with microsatellite instability-high (MSI+) but without detectable germline mutation or hypermethylation in DNA mismatch repair (MMR) genes can be classified as Lynch-like syndrome (LLS). The underlying mechanism and clinical significances of LLS are largely unknown. We measured MSI and MMR protein expression in 4,765 consecutive CRC cases. Among these, MSI+ cases were further classified based on clinical parameters, germline sequencing of MMR genes or polymerase ε (POLE) and δ (POLD1) and promoter methylation analysis of MLH1 and MSH2. We found that MSI+ and MMR protein-deficient CRCs comprised 6.3% (N = 302) of this cohort. On the basis of germline sequencing of 124 cases, we identified 54 LS with MMR germline mutation (LS-MMR), 15 LS with EPCAM deletions (LS-EPCAM) and 55 LLS patients. Of the 55 LLS patients, six (10.9%) had variants of unknown significance in the genes tested, and one patient had a novel somatic mutation (p.S459P) in POLE. In patients with biallelic deletions of EPCAM, all tumors and their matched normal mucosa showed promoter hypermethylation of MSH2. Finally, we found that patients with LLS and LS-EPCAM shared clinical features that differed from LS-MMR patients, including lower frequency of fulfillment of the revised Bethesda guidelines (83.6 and 86.7% vs. 98.1% for LS-MMR) and older mean age at CRC diagnosis (52.6 and 52.7 years vs. 43.9 years for LS-MMR). We identified somatic mutation in POLE as a rare underlying cause for MMR deficiency in LLS. The similarity between LLS and LS-EPCAM suggests LLS as a subset of familial MSI+ CRC.

Tanyi M, Olasz J, Tanyi JL, et al.
MLH1 and MSH2 mutation screening in HNPCC families of Hungary - Two new MMR gene mutations.
Eur J Surg Oncol. 2014; 40(11):1445-52 [PubMed] Related Publications
INTRODUCTION: Hereditary Non-Polyposis Colorectal Cancer is an inherited disease with deleterious germline mutations in the DNA mismatch repair genes causing the development of colon cancer and other malignancies. This is the first study in Hungary screening the population of our colorectal cancer patients in order to identify the prevalence of the disease.
METHODS: In families who met the Modified Amsterdam and Bethesda Criteria the removed tumor tissue was first examined by immunohistochemistry and microsatellite instability analysis. Those cases which showed high microsatellite instability underwent DNA sequencing and multiple ligation dependent probe amplification.
RESULTS: Of the 1576 patients with colorectal cancer underwent screening for the modified Amsterdam and Bethesda criteria, 69 (4.4%) and 166 (10.5%) fulfilled the criteria respectively. 15 patients (31%) of the Amsterdam positive group and 19 patients from the Bethesda positive (18.1%) were MSI-H. There were 8 pathogenic mutations identified in 9 families (60%) in the Amsterdam positive group. 5 mutations were found in 5 families (26%) in the Bethesda positive group. 12 pathogenic mutations were identified, two of these are newly identified, and being published first in this work. These two new mutations were located on MLH1 (g.31276_35231del) and MSH2 (c.969_970delTC) genes.
CONCLUSION: The prevalence of the mutations in the MLH1 and MSH2 genes was almost equal in our Hungarian colorectal cancer patients. One mutation in the MLH1 gene (c.143A > C; p.Q48P) was identified in three different families. Whether this mutation is the most frequent in the Hungarian population is still unidentified and warrant further investigation.

Loconte DC, Patruno M, Lastella P, et al.
A rare MSH2 mutation causes defective binding to hMSH6, normal hMSH2 staining, and loss of hMSH6 at advanced cancer stage.
Hum Pathol. 2014; 45(10):2162-7 [PubMed] Related Publications
Lynch syndrome is caused by germline mutations in 1 of the 4 DNA mismatch repair genes (MLH1, MSH2, MSH6, and PMS2). Mutations in MSH2 cause concomitant loss of hMSH6, whereas MLH1 mutations lead to concurrent loss of PMS2. Much less frequent mutations in MSH6 or PMS2 are associated with the isolated loss of the corresponding proteins. We here demonstrate the causative role of the first germline mutation of MSH2, c.1249-1251 dupGTT (p.417V-418I dupV), associated with normal hMSH2 expression and lack of hMSH6 protein despite a normal MSH6 gene sequence. hMSH6 protein was completely lost only in advanced cancer stages due to 2 different "second hits": a whole MSH2 gene deletion and a frame-shifting insertion in the MSH6 (C)8 repeat in the coding sequence.

Vierkoetter KR, Ayabe AR, VanDrunen M, et al.
Lynch Syndrome in patients with clear cell and endometrioid cancers of the ovary.
Gynecol Oncol. 2014; 135(1):81-4 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
OBJECTIVE: Patients with Lynch Syndrome are at an increased risk for a variety of malignancies, including ovarian cancer. Ovarian cancers associated with Lynch Syndrome are predominantly clear cell or endometrioid in histology. Lynch Syndrome is characterized by germline mutations in mismatch repair (MMR) genes. The current study aims to assess the prevalence of loss of MMR expression in patients with endometrioid and clear cell ovarian carcinoma.
METHODS: A retrospective review identified 90 patients with endometrioid and/or clear cell carcinomas. Slides made from tumor tissue microarray blocks were evaluated using immunohistochemical stains with antibodies against MLH1, PMS2, MSH2, and MSH6. Statistical analysis was performed.
RESULTS: Seven of the 90 cases (7.8%) had loss of MMR expression. The mean age of patients with loss of MMR expression (47 years) was significantly younger than those with retained MMR expression (p=0.014). Loss of MMR expression was present in 20% of patients under the age of 53 with clear cell or endometrioid cancers. Genetic studies found that 3 of the 5 patients with loss of MMR expression carried mutations consistent with Lynch Syndrome; acquired hypermethylation of MLH1 was noted in one patient. Six of 7 patients (86%) whose tumors lacked MMR expression had synchronous or metachronous primary malignancies, a significantly greater prevalence than those with retained MMR expression (p<0.001).
CONCLUSION: Patients under the age of 53 with clear cell or endometrioid ovarian carcinomas are at a clinically significant risk for loss of MMR expression and Lynch Syndrome; routine screening with immunohistochemical staining should be considered.

Wojciechowicz K, Cantelli E, Van Gerwen B, et al.
Temozolomide increases the number of mismatch repair-deficient intestinal crypts and accelerates tumorigenesis in a mouse model of Lynch syndrome.
Gastroenterology. 2014; 147(5):1064-72.e5 [PubMed] Related Publications
BACKGROUND & AIMS: Lynch syndrome, a nonpolyposis form of hereditary colorectal cancer, is caused by inherited defects in DNA mismatch repair (MMR) genes. Most patients carry a germline mutation in 1 allele of the MMR genes MSH2 or MLH1. With spontaneous loss of the wild-type allele, cells with defects in MMR exist among MMR-proficient cells, as observed in healthy intestinal tissues from patients with Lynch syndrome. We aimed to create a mouse model of this situation to aid in identification of environmental factors that affect MMR-defective cells and their propensity for oncogenic transformation.
METHODS: We created mice in which the MMR gene Msh2 can be inactivated in a defined fraction of crypt base columnar stem cells to generate MSH2-deficient intestinal crypts among an excess of wild-type crypts (Lgr5-CreERT2;Msh2(flox/-) mice). Intestinal tissues were collected; immunohistochemical analyses were performed for MSH2, along with allele-specific PCR assays. We traced the fate of MSH2-deficient crypts under the influence of different external factors.
RESULTS: Lgr5-CreERT2;Msh2(flox/-) mice developed more adenomas and adenocarcinomas than control mice; all tumors were MSH2 deficient. Exposure of Lgr5-CreERT2;Msh2(flox/-) mice to the methylating agent temozolomide caused MSH2-deficient intestinal stem cells to proliferate more rapidly than wild-type stem cells. The MSH2-deficient intestinal stem cells were able to colonize the intestinal epithelium and many underwent oncogenic transformation, forming intestinal neoplasias.
CONCLUSIONS: We developed a mouse model of Lynch syndrome (Lgr5-CreERT2;Msh2(flox/-) mice) and found that environmental factors can modify the number and mutability of the MMR-deficient stem cells. These findings provide evidence that environmental factors can promote development of neoplasias and tumors in patients with Lynch syndrome.

Molinari F, Signoroni S, Lampis A, et al.
BRAF mutation analysis is a valid tool to implement in Lynch syndrome diagnosis in patients classified according to the Bethesda guidelines.
Tumori. 2014 May-Jun; 100(3):315-20 [PubMed] Related Publications
AIMS AND BACKGROUND: Lynch syndrome (LS) is clinically defined by the Amsterdam criteria (AC) and by germline mutations in mismatch-repair (MMR) genes leading to microsatellite instability (MSI) at the molecular level. Patients who do not fulfil AC are considered suspected-Lynch according to the less stringent Bethesda guidelines (BG) and should be tested for MSI and MMR germline mutations. BRAF mutations have been proposed as a marker to exclude LS because they are generally absent in LS patients and present in sporadic colorectal cancer (sCRC) with MSI due to promoter hypermethylation of the MLH1 gene. Our aim was to verify whether BRAF mutations may improve the criteria to select patients for germline MMR mutation assessment.
MATERIAL AND METHODS: We analyzed 303 formalin-fixed paraffin-embedded CRC samples including 174 sCRC, 28 patients fulfilling AC, and 101 suspected-Lynch patients fulfilling BG. We analyzed MSI and BRAF mutations in all CRC samples. MLH1, MSH2 and MSH6 germline mutations were investigated in MSI patients fulfilling AC or BG.
RESULTS: sCRC samples showed MSI in 20/174 (11%) cases. BRAF mutations were detected in 10/174 (6%) sCRC cases and were significantly correlated with MSI (P = 0.002). MSI was observed in 24/28 (86%) Amsterdam cases which were BRAF wild-type. MMR gene mutation was detected in 22/26 (85%) AC cases, all showing MSI. Suspected-Lynch cases carried MSI in 41/101 (40%) and BRAF mutations in 7/101 (7%) cases. MMR gene mutation was detected in 13/28 (46%) evaluable MSI patients of this group and only in cases characterized by a wild-type BRAF gene.
CONCLUSIONS: The prevalence of BRAF mutations in CRC patients is not high but extremely correlated with MSI and risk categories as BG, whereas they are absent in LS patients. BRAF mutation detection can reduce the need for MMR gene analysis in a small (but not negligible) proportion of MSI patients (7%), with a positive impact on the financial and psychological costs of unnecessary tests.

Giardiello FM, Allen JI, Axilbund JE, et al.
Guidelines on genetic evaluation and management of Lynch syndrome: a consensus statement by the US Multi-society Task Force on colorectal cancer.
Am J Gastroenterol. 2014; 109(8):1159-79 [PubMed] Related Publications
The Multi-Society Task Force, in collaboration with invited experts, developed guidelines to assist health care providers with the appropriate provision of genetic testing and management of patients at risk for and affected with Lynch syndrome as follows: Figure 1 provides a colorectal cancer risk assessment tool to screen individuals in the office or endoscopy setting; Figure 2 illustrates a strategy for universal screening for Lynch syndrome by tumor testing of patients diagnosed with colorectal cancer; Figures 3,4,5,6 provide algorithms for genetic evaluation of affected and at-risk family members of pedigrees with Lynch syndrome; Table 10 provides guidelines for screening at-risk and affected persons with Lynch syndrome; and Table 12 lists the guidelines for the management of patients with Lynch syndrome. A detailed explanation of Lynch syndrome and the methodology utilized to derive these guidelines, as well as an explanation of, and supporting literature for, these guidelines are provided.

Park DJ, Tao K, Le Calvez-Kelm F, et al.
Rare mutations in RINT1 predispose carriers to breast and Lynch syndrome-spectrum cancers.
Cancer Discov. 2014; 4(7):804-15 [PubMed] Article available free on PMC after 01/12/2015 Related Publications
UNLABELLED: Approximately half of the familial aggregation of breast cancer remains unexplained. A multiple-case breast cancer family exome-sequencing study identified three likely pathogenic mutations in RINT1 (NM_021930.4) not present in public sequencing databases: RINT1 c.343C>T (p.Q115X), c.1132_1134del (p.M378del), and c.1207G>T (p.D403Y). On the basis of this finding, a population-based case-control mutation-screening study was conducted that identified 29 carriers of rare (minor allele frequency < 0.5%), likely pathogenic variants: 23 in 1,313 early-onset breast cancer cases and six in 1,123 frequency-matched controls [OR, 3.24; 95% confidence interval (CI), 1.29-8.17; P = 0.013]. RINT1 mutation screening of probands from 798 multiple-case breast cancer families identified four additional carriers of rare genetic variants. Analysis of the incidence of first primary cancers in families of women carrying RINT1 mutations estimated that carriers were at increased risk of Lynch syndrome-spectrum cancers [standardized incidence ratio (SIR), 3.35; 95% CI, 1.7-6.0; P = 0.005], particularly for relatives diagnosed with cancer under the age of 60 years (SIR, 10.9; 95% CI, 4.7-21; P = 0.0003).
SIGNIFICANCE: The work described in this study adds RINT1 to the growing list of genes in which rare sequence variants are associated with intermediate levels of breast cancer risk. Given that RINT1 is also associated with a spectrum of cancers with mismatch repair defects, these findings have clinical applications and raise interesting biological questions.

Giardiello FM, Allen JI, Axilbund JE, et al.
Guidelines on genetic evaluation and management of Lynch syndrome: a consensus statement by the US Multi-Society Task Force on colorectal cancer.
Gastroenterology. 2014; 147(2):502-26 [PubMed] Related Publications
The Multi-Society Task Force, in collaboration with invited experts, developed guidelines to assist health care providers with the appropriate provision of genetic testing and management of patients at risk for and affected with Lynch syndrome as follows: Figure 1 provides a colorectal cancer risk assessment tool to screen individuals in the office or endoscopy setting; Figure 2 illustrates a strategy for universal screening for Lynch syndrome by tumor testing of patients diagnosed with colorectal cancer; Figures 3-6 provide algorithms for genetic evaluation of affected and at-risk family members of pedigrees with Lynch syndrome; Table 10 provides guidelines for screening at-risk and affected persons with Lynch syndrome; and Table 12 lists the guidelines for the management of patients with Lynch syndrome. A detailed explanation of Lynch syndrome and the methodology utilized to derive these guidelines, as well as an explanation of, and supporting literature for, these guidelines are provided.

Everett JN, Raymond VM, Dandapani M, et al.
Screening for germline mismatch repair mutations following diagnosis of sebaceous neoplasm.
JAMA Dermatol. 2014; 150(12):1315-21 [PubMed] Related Publications
IMPORTANCE Sebaceous neoplasms (SNs) define the Muir-Torre syndrome variant of Lynch syndrome (LS), which is associated with increased risk for colon and other cancers necessitating earlier and more frequent screening to reduce morbidity and mortality.Immunohistochemical (IHC) staining for mismatch repair (MMR) proteins in SNs can be used to screen for LS, but data on subsequent germline genetic testing to confirm LS diagnosis are limited.OBJECTIVE To characterize the utility of IHC screening of SNs in identification of germline MMR mutations confirming LS.DESIGN, SETTING, AND PARTICIPANTS Retrospective study at 2 academic cancer centers of 86 adult patients referred for clinical genetics evaluation after diagnosis of SN.MAIN OUTCOMES AND MEASURES Results of tumor IHC testing and germline genetic testing were reviewed to determine positive predictive value and sensitivity of IHC testing in diagnosis of LS. Clinical variables, including age at diagnosis of SN, clinical diagnostic criteria for LS and Muir-Torre syndrome, and family history characteristics were compared between mutation carriers and noncarriers.RESULTS Of 86 patients with SNs, 25 (29%) had germline MMR mutations confirming LS.Among 77 patients with IHC testing on SNs, 38 (49%) had loss of staining of 1 or more MMR proteins and 14 had germline MMR mutations. Immunohistochemical analysis correctly identified 13 of 16 MMR mutation carriers, corresponding to 81% sensitivity. Ten of 12 patients(83%) with more than 1 SN had MMR mutations. Fifty-two percent of MMR mutation carriers did not meet clinical diagnostic criteria for LS, and 11 of 25 (44%) did not meet the clinical definition of Muir-Torre syndrome. CONCLUSIONS AND RELEVANCE Immunohistochemical screening of SNs is effective in identifying patients with germline MMR mutations and can be used as a first-line test when LSis suspected. Abnormal IHC results, including absence of MSH2, are not diagnostic of LS and should be interpreted cautiously in conjunction with family history and germline genetic testing. Use of family history to select patients for IHC screening has substantial limitations,suggesting that universal IHC screening of SNs merits further study. Clinical genetics evaluation is warranted for patients with abnormal IHC test results, normal IHC test results with personal or family history of other LS-associated neoplasms, and/or multiple SNs.

Ngeow J, Eng C
BluepRINT for moderate-to-low penetrance cancer susceptibility genes needed: breast cancer and beyond.
Cancer Discov. 2014; 4(7):762-3 [PubMed] Related Publications
SUMMARY: RINT1 is a novel moderately penetrant cancer susceptibility gene seen in breast cancer as well as possibly in Lynch syndrome-related cancers.

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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