paywalled: Mismatch repair analysis of inherited MSH2 and/or MSH6 variation pairs found in cancer patients - Kantelinen - Human Mutation - Wiley Online Library

Mismatch repair analysis of inherited MSH2 and/or MSH6 variation pairs found in cancer patients - Kantelinen - Human Mutation

Abstract

Mismatch repair (MMR) malfunction causes the accumulation of mismatches in the genome leading to genomic instability and cancer. The inactivation of an MMR gene (MSH2, MSH6, MLH1 or PMS2) with an inherited mutation causes Lynch syndrome (LS), a dominant susceptibility to cancer. MMR gene variants of uncertain significance (VUS) may be pathogenic mutations which cause LS, may result in moderately increased cancer risks, or may be harmless polymorphisms. Our study suggests that an inherited MMR VUS individually assessed as proficient may, however, in a pair with another MMR VUS found in the same colorectal cancer (CRC) patient have a concomitant contribution to the MMR deficiency. Here, eight pairs of MMR gene variants found in cancer patients were functionally analyzed in an in vitro MMR assay. Although the other pairs do not suggest a compound deficiency, the MSH2 VUS pair c.380A>G/c.982G>C (p.Asn127Ser/p.Ala328Pro), which nearly halves the repair capability of the wild type MSH2 protein, is presumed to increase the cancer risk considerably. Moreover, two MSH6 variants, c.1304T>C (p.Leu435Pro) and c.1754T>C (p.Leu585Pro), were shown to be MMR deficient. The role of one of the most frequently reported MMR gene VUS, MSH2 c.380A>G (p.Asn127Ser), is especially interesting, since its concomitant defect with another variant could finally explain its recurrent occurrence in CRC patients.

American Society for Clinical Pathology: Molecular Testing in Colorectal Cancer (Lynch Syndrome/MLH1, MSH2, MSH6, PMS2/MSI-H/KRAS/BRAF.....)

Blogger's Note: focus (obviously) on colorectal cancer, however, the cancer spectrum of Lynch Syndrome is noted in this paper as well as the shortcomings of the Bethesda Guidelines

 Molecular Testing in Colorectal Cancer

Conclusion

In summary, current standard-of-care molecular testing of CRC is aimed at detecting Lynch syndrome and KRAS mutations. However, with recent rapid development of biological agents targeted against components of the EGFR signaling cascade in the treatment of CRCs, mutational analysis of the genes in the EGFR signaling pathway may become a standard of care for patients with CRC in the near future. Ideally, identifying molecular prognostic and predictive factors may allow us to identify high-risk patients with stage II CRC who will benefit from chemotherapy after surgery. In addition, this may allow us to determine patients’ eligibility for targeted biological therapies.

abstract: Unusual DNA mismatch repair-deficient tumors in Lynch syndrome: a report of new cases and review of the literature.

Unusual DNA mismatch repair-deficient tumors in Lynch syndrome: a report of new cases and review of the literature.

Hum Pathol. 2012 Apr 17;


Abstract

Immunohistochemical detection of DNA mismatch repair proteins and polymerase chain reaction detection of microsatellite instability have enhanced the recognition of mismatch repair-deficient neoplasms in patients with Lynch syndrome and, consequently, led to the identification of tumors that have not been included in the currently known Lynch syndrome tumor spectrum.

Here, we report 4 such unusual tumors. Three of the 4, a peritoneal mesothelioma, a pancreatic acinar cell carcinoma, and a pancreatic well-differentiated neuroendocrine tumor, represented tumor types that, to the best of our knowledge, have not been previously reported in Lynch syndrome. The fourth tumor was an adrenocortical carcinoma, which has rarely been reported previously in Lynch syndrome. Three of our 4 patients carried a pathogenic germ-line mutation in a mismatch repair gene. The unusual tumor in each of the 3 patients showed loss of the mismatch repair protein corresponding to the mutation. The fourth patient did not have mutation information but had a history of colonic and endometrial carcinomas; both lacked MSH2 and MSH6 proteins. Interestingly, none of the 4 unusual tumors revealed microsatellite instability on polymerase chain reaction testing, whereas an appendiceal carcinoma from 1 of the study patients who was tested simultaneously did. The recognition of such tumors expands the repertoire of usable test samples for the workup of high-risk families.

As yet, however, there are no data to support the inclusion of these tumors into general screening guidelines for detecting Lynch syndrome, nor are there data to warrant surveillance for these tumors in patients with Lynch syndrome.

open access: Gynecologic Oncology Case Reports - A case of endometrial cancer in the context of a BRCA2 mutation and double heterozygosity for Lynch syndrome

ScienceDirect.com - Gynecologic Oncology Case Reports - A case of endometrial cancer in the context of a BRCA2 mutation and double heterozygosity for Lynch syndrome

 "....While endometrial cancer diagnosed under the age of 50 is not included in the Revised Bethesda Guideline, evidence suggests that these individuals should be evaluated for Lynch syndrome (Resnick et al., 2009). The patient presented was diagnosed with endometrial cancer at the age of 41 and genetic testing revealed triple heterozygosity for BRCA2, MLH1 and MSH6 mutations."

 Introduction

Lynch syndrome, also called hereditary non-polyposis colorectal cancer (HNPCC), is an autosomal dominant cancer susceptibility syndrome caused by germline mutations in DNA mismatch repair (MMR) genes, MLH1, MSH2, and less frequently MSH6 and PMS2. MMR mutation carriers are predisposed primarily to colorectal cancer and endometrial cancer, with an increased frequency of stomach, ovary, pancreas, upper urinary tract, brain, small bowel, and skin consistently reported. This hereditary syndrome accounts for approximately 2–3% of colorectal cancers and 1–4% of endometrial cancers in the United States (Lynch and de la Chapelle, 2003). Depending on the MMR gene involved, women with Lynch syndrome can have up to an 80% lifetime risk of developing colorectal cancer, and a 20–60% risk of endometrial cancer.

Germline mutations in BRCA1 or BRCA2 (BRCA1/2) cause hereditary breast ovarian cancer syndrome. Female carriers of BRCA1/2 mutations have excessive risks for both breast and ovarian cancer, with lifetime breast cancer estimates ranging from 45% to 84%, and lifetime ovarian cancer estimates ranging from 11% to 62%, depending upon the population studied. BRCA1/2 kindreds are also noted to have an increased frequency of prostate cancer, and in BRCA2 kindreds, increased frequencies of pancreatic cancer and melanoma are observed. The frequency of BRCA1 or BRCA2 mutations in the general population is estimated to be 1 in 300 to 1 in 800, respectively (King et al., 2003).

While there are kindreds with more than one cancer susceptibility syndrome and/or mutation reported in the literature ( [Thiffault et al., 2004] and [Smith et al., 2008]), they are not often encountered in routine clinical settings........

Highlights

► Endometrial cancer with BRCA2 mutation and double heterozygosity for Lynch syndrome.
► Loss of MLH1 and PMS2 by immunohistochemical stain.
► MSH1 and MSH6 gene mutations by genomic sequencing.

abstract: Uroepithelial (bladder/ureter) and kidney carcinoma in Lynch syndrome (MSH2)

Uroepithelial and kidney carcinoma in Lynch syndrome [Fam Cancer. 2012] - PubMed - NCBI
 

Fam Cancer. 2012 Apr 4

Abstract

Increased risk for urological tumors has been observed in mutation carriers with Lynch syndrome (LS). In this study, we evaluated the clinical features of uroepithelial (bladder and ureter) and kidney cancers in 974 Finnish mutation carriers. Altogether 30 patients had a total of 34 urological tumors: 12 ureter, 12 bladder, and 10 kidney cancers. Urological tumor was the only tumor in 9 (30 %) patients, and metachronous other tumor occurred in 21 (70 %). The occurrence of uroepithelial cancers was significantly higher in MSH2 mutation carriers (6 %) than in MLH1 carriers (2 %) and MSH6 mutation carriers (0 %).

The mean ages of patients at the time of diagnosis were: bladder cancer, 57 years; ureter cancer, 58 years; and kidney cancer, 64 years. Overall 5-year survival rates were 70 % in bladder cancer, 81 %  in ureter cancer, and 75 % in kidney cancer.

Cancer-specific 5-year survival rates were 70 %  in bladder cancer, 91 %  in ureter cancer, and 100 % in kidney cancer.

In conclusion, early age of onset was observed in patients with uroepithelial tumors, but not in patients with kidney cancer. The frequency of uroepithelial tumors was significantly higher in MSH2 mutation carriers than in MLH1 carriers. Further studies with larger numbers of patients, however, are needed to evaluate the potential benefit of surveillance of urological tumors in LS.

abstract: (Lynch Syndrome) Colorectal and Other Cancer Risks for Carriers and Noncarriers From Families With a DNA Mismatch Repair Gene Mutation: A Prospective Cohort Study [Epidemiology] multi-national study

 Blogger's Note: some stats deleted for ease of reading, see abstract (or paid subscription for full details; interesting stat on female breast cancer


Colorectal and Other Cancer Risks for Carriers and Noncarriers From Families With a DNA Mismatch Repair Gene Mutation: A Prospective Cohort Study [Epidemiology]:

Purpose
To determine whether cancer risks for carriers and noncarriers from families with a mismatch repair (MMR) gene mutation are increased above the risks of the general population.

Patients and Methods
We prospectively followed a cohort of 446 unaffected carriers of an MMR gene mutation (MLH1, n = 161; MSH2, n = 222; MSH6, n = 47; and PMS2, n = 16) and 1,029 their unaffected relatives who did not carry a mutation every 5 years at recruitment centers of the Colon Cancer Family Registry. For comparison of cancer risk with the general population, we estimated country-, age-, and sex-specific standardized incidence ratios (SIRs) of cancer for carriers and noncarriers.
Results
Over a median follow-up of 5 years, mutation carriers had an increased risk of

colorectal cancer (20.48),
endometrial cancer (30.62),  
ovarian cancer (18.81),
renal cancer (11.22),
pancreatic cancer ( 10.68), 
gastric cancer (9.78),  
urinary bladder cancer (9.51), and  
female breast cancer ( 3.95;).

We found no evidence of their noncarrier relatives having an increased risk of any cancer, including CRC (1.02).

Conclusion 
 We confirmed that carriers of an MMR gene mutation were at increased risk of a wide variety of cancers, including some cancers not previously recognized as being a result of MMR mutations, and found no evidence of an increased risk of cancer for their noncarrier relatives.

open access: BMC Cancer - Predictive models for mutations in mismatch repair genes: implication for genetic counseling in developing countries (Lynch Syndrome)

 Background

Lynch syndrome (LS) is the most common form of inherited predisposition to colorectal cancer (CRC), accounting for 2–5% of all CRC. LS is an autosomal dominant disease characterized by mutations in the mismatch repair genes mutL homolog 1 (MLH1), mutS
homolog 2 (MSH2), postmeiotic segregation increased 1 (PMS1), post-meiotic segregation increased 2 (PMS2) and mutS homolog 6 (MSH6). Mutation risk prediction models can be incorporated into clinical practice, facilitating the decision-making process and identifying
individuals for molecular investigation. This is extremely important in countries with limited economic resources. This study aims to evaluate sensitivity and specificity of five predictive models for germline mutations in repair genes in a sample of individuals with suspected
Lynch syndrome.

"Lynch syndrome (LS) is the most common form of inherited predisposition to colorectal cancer (CRC), accounting for 2–5% of all CRC [1]. Colorectal cancer in LS differs from sporadic cases by an earlier age of diagnosis (mean age approximately 44 years), a predominance of proximally-sited colon cancers (60–70%) and an increased propensity to
synchronous or metachronous CRCs (25%) [2,3]. Individuals with LS have an 80% probability of developing CRC at 65 years, and they are at an elevated risk of developing a second primary CRC [4] as well as at an increased risk for extra-colonic malignancies, including endometrial, gastric, small bowel, urological tract, ovary, pancreas and brain cancer
[5]."

 Conclusions

The Barnetson, PREMM, MMRpro and Wijnen models present similar AUC. The AUC of the Myriad model is statistically inferior to the four other models. 

The complete article is available as a provisional PDF. The fully formatted PDF and HTML versions are in production.

abstract - Identification of Cancer Patients with Lynch Syndrome: Clinically Significant Discordances and Problems in Tissue-Based Mismatch Repair Testing

abstract: Synchronous gynecologic malignancy and preliminary results of Lynch syndrome (Korean women)

METHODS:

Thirty six women with synchronous gynecologic tumors of endometrial and ovarian cancer were identified among patients being treated at our institution.

CONCLUSION:

In this study, the frequency of Lynch syndrome associated immunohistochemical staining (MLH1, MSH2, and MSH6) group was estimated as 9% (3/32) among Korean women with synchronous gynecologic tumors.

The founder Ashkenazi Jewish mutations in the MSH2 and MSH6 genes in Israeli patients with gastric and pancreatic cancer

Abstract

The genetic basis for gastric and pancreatic cancer is largely undetermined.
These cancers are overrepresented in hereditary non polyposis colon cancer (HNPCC), inherited cancer syndrome attributed to germline mutations primarily in the MSH2, MLH1 and MSH6 genes.
Among Ashkenazi Jewish HNPCC cases, recurring mutations in the MSH2 (1906G>C; A636P) and MSH6 (c.3984_3987dupGTCA; c.3959_3962delCAAG) genes can be detected. The MSH6*c.3984_3987dupGTCA mutation was recently detected in an Ashkenazi family with inherited gastric cancer. We hypothesized that it may be possible to detect the recurring MSH2 and MSH6 mutations in Jewish individuals with familial and sporadic gastric and pancreatic cancer.
To test this notion, we genotyped 143 unrelated Jewish Israeli patients with gastric (n = 23) and pancreatic (n = 120) cancer. The majority of cases (100/143–70%) were Ashkenazi Jews, and 10% (n = 16)—of mixed Ashkenazi-non Ashkenazi Jewish ancestry, and most participants (n = 96–67.1%) had a positive family history of cancer. Genotyping the MSH2*A636P mutation was performed by PCR followed by restriction enzyme digest, and the MSH6*c.3984_3987dupGTCA and c.3959_3962delCAAG mutations were detected by fragment size analysis by capillary electrophoresis and sequencing. None of the participants harbored any of the genotyped MSH2 or MSH6 mutations.
We conclude that the recurring Ashkenazi MSH2 and MSH6 mutations contribute little if any to sporadic and familial gastric and pancreatic cases in Israeli patients"

MLH1/MSH2/MSH6 (Lynch Syndrome) Study Identifies Genetic Mutations Associated With Cancer Risk For Hereditary Cancer Syndrome - media

"The researchers found significant differences in estimated cumulative cancer risk between the 3 mutated genes......"
"This analysis of a nationwide series of 537 families with Lynch syndrome provides age- and gene-specific risk estimates for each tumor of the spectrum. The results should help clarify the phenotypic differences between MSH6, MLH1, or MSH2 mutation carriers and highlight the clinical significance of the risk of gynecological (and especially ovarian) cancers," the researchers conclude."

MSH6 - Defects in MSH6 are the cause of (Lynch Syndrome) hereditary non-polyposis colorectal cancer type 5 (HNPCDNA mismatch repair protein Msh6 - Homo sapiens (Human)

Defects in MSH6 are the cause of hereditary non-polyposis colorectal cancer type 5 (HNPCC5) [MIM:600678]. Mutations in more than one gene locus can be involved alone or in combination in the production of the HNPCC phenotype (also called Lynch syndrome). Most families with clinically recognized HNPCC have mutations in either MLH1 or MSH2 genes. HNPCC is an autosomal, dominantly inherited disease associated with marked increase in cancer susceptibility. It is characterized by a familial predisposition to early onset colorectal carcinoma (CRC) and extra-colonic cancers of the gastrointestinal, urological and female reproductive tracts. HNPCC is reported to be the most common form of inherited colorectal cancer in the Western world. Cancers in HNPCC originate within benign neoplastic polyps termed adenomas.

Clinically, HNPCC is often divided into two subgroups. Type I: hereditary predisposition to colorectal cancer, a young age of onset, and carcinoma observed in the proximal colon. Type II: patients have an increased risk for cancers in certain tissues such as the uterus, ovary, breast, stomach, small intestine, skin, and larynx in addition to the colon. Diagnosis of classical HNPCC is based on the Amsterdam criteria: 3 or more relatives affected by colorectal cancer, one a first degree relative of the other two; 2 or more generation affected; 1 or more colorectal cancers presenting before 50 years of age; exclusion of hereditary polyposis syndromes.

MSH6 mutations appear to be associated with atypical HNPCC and in particular with development of endometrial carcinoma or atypical endometrial hyperplasia, the presumed precursor of endometrial cancer. Defects in MSH6 are also found in familial colorectal cancers (suspected or incomplete HNPCC) that do not fulfill the Amsterdam criteria for HNPCC. Ref.17 Ref.31 Ref.33 Ref.38 Ref.41 Ref.45 Ref.46

abstract: Familial Cancer, A putative Lynch syndrome family carrying MSH2 and MSH6 variants of uncertain significance—functional analysis reveals the pathological one

Abstract

Inherited pathogenic mutations in the mismatch repair (MMR) genes, MSH2, MLH1, MSH6, and PMS2 predispose to Lynch syndrome (LS). However, the finding of a variant or variants of uncertain significance (VUS) in affected family members complicates the risk assessment. Here, we describe a putative LS family carrying VUS in both MSH2 (c.2768T>A, p.Val923Glu) and MSH6 (c.3563G>A, p.Ser1188Asn). Two colorectal cancer (CRC) patients were studied for mutations and identified as carriers of both variants. In spite of a relatively high mean age of cancer onset (59.5 years) in the family, many CRC patients and the tumor pathological data suggested that the missense variation in MSH2, the more common susceptibility gene in LS, would be the predisposing alteration. However, MSH2 VUS was surprisingly found to be MMR proficient in an in vitro MMR assay and a tolerant alteration in silico. By supplying evidence that instead of MSH2 p.Val923Glu the MSH6 p.Ser1188Asn variant is completely MMR-deficient, the present study confirms the previous findings, and suggests that MSH6 (c.3563G>A, p.Ser1188Asn) is the pathogenic mutation in the family. Moreover, our results strongly support the strategy to functionally assess all identified VUS before predictive gene testing and genetic counseling are offered to a family.

abstract: Ovarian cancer linked to lynch syndrome typically presents as early-onset, non-serous epithelial tumors (endometrioid/clear cell cell types) MSH2 MSH6 MLH1

Ovarian cancer linked to lynch syndrome typically presents as early-onset, non-serous epithelial tumors.

Abstract

OBJECTIVE: Heredity is a major cause of ovarian cancer and during recent years the contribution from germline mismatch repair (MMR) gene mutations linked to Lynch syndrome has gradually been recognized.

METHODS: We characterized clinical features, tumor morphology and mismatch repair defects in all ovarian cancers identified in Swedish and Danish Lynch syndrome families.

RESULTS: In total, 63 epithelial ovarian cancers developed at mean 48 (range 30-79) years of age with 47% being early stage (FIGO stage I). Histologically, endometrioid (35%) and clear cell (17%) tumors were overrepresented. The underlying MMR gene mutations in these families affected MSH2 in 49%, MSH6 in 33% and MLH1 in 17%. Immunohistochemical loss of the corresponding MMR protein was demonstrated in 33/36 (92%) tumors analyzed.

CONCLUSION: The combined data from our cohorts demonstrate that ovarian cancer associated with Lynch syndrome typically presents at young age as early-stage, non-serous tumors, which implicates that a family history of colorectal and endometrial cancer should be specifically considered in such cases.

full free access: (2010) MSH6 and PMS2 mutation positive Australian Lynch syndrome families: novel mutations, cancer risk and age of diagnosis of colorectal cancer

Background

Approximately 10% of Lynch syndrome families have a mutation in MSH6 and fewer families have a mutation in PMS2. It is assumed that the cancer incidence is the same in families with mutations in MSH6 as in families with mutations in MLH1/MSH2 but that the disease tends to occur later in life, little is known about families with PMS2 mutations. This study reports on our findings on mutation type, cancer risk and age of diagnosis in MSH6 and PMS2 families..........cont'd

"Lynch syndrome is an autosomal dominantly inherited cancer syndrome characterised by early onset epithelial cancers. Patients with Lynch syndrome have an increased risk of developing malignancies during their lifetime, at a mean age of disease onset that is significantly lower than that observed in the general population. In addition to the high risk of developing CRC, Lynch syndrome patients are also at risk of developing malignancies in a variety of organs that include the uterus, small bowel, stomach, ovary, bladder, pancreas and the urinary tract [2,3]."

abstract: Challenging cases encountered in colorectal cancer screening for Lynch syndrome reveal novel findings: nucleolar MSH6 staining and impact of prior chemoradiation therapy

abstract: The PREMM(1,2,6) model predicts risk of MLH1, MSH2, and MSH6 germline mutations based on cancer history (Lynch Syndrome)

The rate of the predominant Jewish mutations in the BRCA1, BRCA2, MSH2 and MSH6 genes in unselected Jewish endometrial cancer patients (study number 289 patients)

Note: MSH2/MSH6 are 2 of the Lynch Syndrome genes

Objectives

The genes associated with familial Endometrial Cancer (EC) are largely unknown. While EC is an integral part of Hereditary Non-Polyposis Colon Cancer, there is an ongoing debate if EC is indeed overrepresented in hereditary breast/ovarian cancer families.

Conclusions

Our data do not support screening for BRCA1/2 mutations in consecutive EC patients.

Low Frequency of Lynch Sydrome among Young Patients with Non-Familial Colorectal Cancer

Note: "young" referred to as those less than 50 yrs age

abstract/free full access: Current clinical criteria for Lynch syndrome are not sensitive enough to identify MSH6 mutation carriers -- Sjursen et al. -- Journal of Medical Genetics

Conclusion:
Amsterdam criteria and each of the Bethesda criteria were inadequate for identifying MSH6 mutation-carrying kindreds. MSH6 mutations may be more common than currently assumed, and the penetrance/expression of MSH6 mutations, as derived from families meeting current clinical criteria, may be misleading. To increase detection rate of MMR mutation carriers, all cancers in the Lynch syndrome tumour spectrum should be subjected to immunohistochemical analysis and/or analysis for microsatellite instability.