Germline Mutations In MSH2 Research Articles

Differences in outcome between colorectal cancer (CRC) patients (pts) with Lynch syndrome (LS) versus MLH1 hypermethylation (MLH1 HM).

1556 Background: In ~15% of CRC tumors mismatch repair deficiency (dMMR) is observed and is usually caused by LS (germline mutations in MLH1, MSH2, MSH6 or PMS2) or sporadic inactivation of MLH1 (hypermethylation [HM] of MLH1 gene promoter). The objective of this study was to retrospectively compare clinical factors and outcomes in pts with dMMR with LS to those without LS. Methods: This cohort includes pts with CRC diagnosed between 5/98 and 5/12 with dMMR on immunohistochemistry (IHC) staining. Prior to 2006 pts came from the Columbus area HNPCC study. After 2006, we included all CRC pts at OSU as universal IHC was initiated. Chi-square was used to compare nominal parameters and log-rank to compare overall survival (OS). Results: A total of 189 pts had dMMR per IHC staining (see characteristics in table). In 36 pts (19.0%) a diagnosis of LS was made after germline testing, in 59 pts (31.2%) a diagnosis of MLH1 HM was made with methylation or BRAF testing, in 65 pts (34.4%) a LS or MLH1 HM diagnosis was assumed based on clinical criteria. Median OS was 159 mos in the LS group and 49 mos in the MLH1MH group (p=0.003) and OS was significantly longer in the LS group across all 4 stages (p=0.002) (see Table). Conclusions: Pts with LS-associated CRC had longer OS than pts with MLH1 HM-associated CRC, even in the setting of a higher incidence of other cancers (44.1% vs. 28%). This is likely related to younger age in the LS group. The MLH1HM group was older at diagnosis and more often female. There are a number of limitations to our study including the potential for survivorship bias and lack of a definitive diagnosis in ~50% of patients despite using clinical criteria to define these pts. [Table: see text]

Genotype–phenotype correlation in MMR mutation-positive families with Lynch syndrome

Hereditary nonpolyposis colorectal cancer (HNPCC) is caused by heterozygous mutations in mismatch repair (MMR) genes. Approximately 85% of genetically defined HNPCC patients have germline mutations in MLH1 and MSH2. HNPCC patients are at increased risk of developing extracolonic cancers. The early age of onset, predominantly right-sided colon cancers, and synchronous and metachronous cancers are other features of the syndrome. HNPCC shows heterogeneous clinical phenotypes, and differences in gene mutation frequencies have been observed in some countries. Several investigators have tried to correlate the phenotype with the affected gene. A total of 46 individuals from 22 unrelated families, of the 264 families fulfilling the inclusion criteria, with deleterious mutations in MLH1, MSH2, or MSH6 genes were identified. We evaluated these clinicopathological features in their relation to different genetic parameters (gene mutated, type of mutation, or alteration of the MMR system in high-risk families) in order to establish a relationship between the phenotype and the genotype in our series. The phenotype of the disease seems not to be influenced by the type of mutation, but rather by the mutated gene. The presence of multiple tumors is associated with mutations in the MSH2 gene. The mean age at diagnosis of the first colorectal cancer (CRC) was almost identical in families with mutations in MLH1 and MSH2, about 50years of age, but this age may increase by almost 10years for MSH6 mutation carriers. The identification of genotype-phenotype correlations could provide a more specific surveillance program focused on the individualized risk.

Abstract 40: Mutation of EPCAM gene is less frequent in Korean and EPCAM immunohistochemistry can identify Lynch syndrome in patients who do not meet Bethesda criteria.

Abstract Lynch syndrome is an inherited tumor predisposition syndrome caused by germline mutations of DNA mismatch repair (MMR) genes, mainly MLH1 and MSH2. Recently, germline deletions affecting the epithelial cell adhesion molecule (EPCAM) gene located upstream of MSH2 were identified as a novel mutational mechanism causing Lynch syndrome. However, most studies were conducted in western populations, where the incidence of CRC is high. To identify the incidence of germline deletions of EPCAM gene in Korea where the incidence of CRC is relatively low and socioeconomic condition is different, we conducted a comprehensive study in 4,993 patients diagnosed and treated with CRCs at a single institute between 2006 and 2011. In all tumor samples, microsatellite instability (MSI) test and immunohistochemistry (IHC) for MMR proteins were performed. In cases with loss of MLH1 protein, methylation of MLH1 by MethyLight was performed and cases with hypermethylation of MLH1 gene were excluded. Germline mutations of MLH1, MSH2 and MSH6 were performed in patients who fulfilled at least one of the revised Bethesda criteria. In 97 patients with loss of MSH2 protein, EPCAM IHC and multiplex ligation-dependent probe amplification for germline deletions of the EPCAM and MSH2 gene were performed. Loss of expression of MMR proteins and/or MSI-high was observed in 337 (6.7%) patients, 112 (2.2%) patients met revised Bethesda criteria, and 54 (1.1%) patients harbored germline mutations of MMR genes. Out of 97 MSH2-negative CRCs, 5 (5.2%) showed concomitant loss of EPCAM expression and EPCAM exon 9 deletionmutations. Out of 5 cases with EPCAM mutation and protein loss, four patients showed familial histories of CRCs. However, one patient showed no family history. In this patient, although multiple liver metastases were the first manifestation, he lived 6 more years after diagnosis. In this large single study cohort, we found that 5.2% of MSH2-negative CRCs were caused by EPCAM deletion mutations, which is lower than previously reported incidences in western populations. Moreover, we could find one candidate patient with de novo mutation of EPCAM gene, which has not been reported yet. Our results strongly support that in routine screening of patients with CRC for Lynch syndrome, a simple and sensitive EPCAM IHC should be included even in cases do not meet Bethesda criteria. Citation Format: So Young Kang, Shin Woo Kang, In-Gu Do, Dong Kyung Chang, Kyoung M. Kim. Mutation of EPCAM gene is less frequent in Korean and EPCAM immunohistochemistry can identify Lynch syndrome in patients who do not meet Bethesda criteria. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 40. doi:10.1158/1538-7445.AM2013-40

Simple Detection of Germline Microsatellite Instability for Diagnosis of Constitutional Mismatch Repair Cancer Syndrome

Heterozygous mutations in DNA mismatch repair (MMR) genes result in predisposition to colorectal cancer (hereditary nonpolyposis colorectal cancer or Lynch syndrome). Patients with biallelic mutations in these genes, however, present earlier, with constitutional mismatch repair deficiency cancer syndrome (CMMRD), which is characterized by a spectrum of rare childhood malignancies and café-au-lait skin patches. The hallmark of MMR deficiency, microsatellite instability (MSI), is readily detectable in tumor DNA in Lynch syndrome, but is also present in constitutional DNA of CMMRD patients. However, detection of constitutional or germline MSI (gMSI) has hitherto relied on technically difficult assays that are not routinely applicable for clinical diagnosis. Consequently, we have developed a simple high-throughput screening methodology to detect gMSI in CMMRD patients based on the presence of stutter peaks flanking a dinucleotide repeat allele when amplified from patient blood DNA samples. Using the three different microsatellite markers, the gMSI ratio was determined in a cohort of normal individuals and 10 CMMRD patients, with biallelic germline mutations in PMS2 (seven patients), MSH2 (one patient), or MSH6 (two patients). Subjects with either PMS2 or MSH2 mutations were easily identified; however, this measure was not altered in patients with CMMRD due to MSH6 mutation.

Muir–Torre syndrome-associated pleomorphic liposarcoma arising in a previous radiation field

Muir-Torre syndrome is a variant of Lynch syndrome, characterised by sebaceous neoplasia and/or keratoacanthomas associated with visceral malignancies. Muir-Torre syndrome is caused by germline mutations of one of the mismatch repair genes, frequently MSH2 and less frequently MLH1 and MSH6. Visceral malignancies associated with Muir-Torre syndrome and Lynch syndrome include colorectal, endometrial and other gastrointestinal, urological and gynaecological malignancies. Small numbers of Lynch syndrome-associated soft tissue sarcomas have been reported, but there are no reported cases of soft tissue sarcomas in Muir-Torre syndrome. In this study, we report a 74-year-old man with known Muir-Torre syndrome with confirmed MSH2 germline mutation, diagnosed with pleomorphic liposarcoma of the right buttock in a previous radiation field. The tumour showed loss of expression of MSH2 and MSH6 on immunohistochemistry. Immunohistochemistry on another pleomorphic liposarcoma in a different patient with no previous history of Muir-Torre syndrome or Lynch syndrome showed no loss of expression of mismatch repair proteins. This is the first report of Muir-Torre syndrome-associated sarcoma and the first case of post-radiation sarcoma in Lynch syndrome.

Cancer Risks Associated With Germline Mutations in MLH1, MSH2, and MSH6 Genes in Lynch Syndrome

Cancer Risks Associated With Germline Mutations in MLH1, MSH2, and MSH6 Genes in Lynch Syndrome

Muir–torre syndrome-associated pleomorphic liposarcoma arising in a previous radiation field

Background Muir–Torre syndrome is a variant of Lynch syndrome, characterised by sebaceous neoplasia and/or keratoacan-thomas associated with visceral malignancies. Muir–Torre syndrome is caused by germline mutations of one of the mismatch repair genes, frequently MSH2 and less frequently MLH1 and MSH6. Visceral malignancies associated with Muir–Torre syndrome and Lynch syndrome include colorectal, endometrial and other gastrointestinal, urological and gynaecological malignancies. Small numbers of Lynch syndrome-associated soft tissue sarcomas have been reported but there are no reported cases of soft tissue sarcomas in Muir–Torre syndrome. Aim and Methods In this study, we report a 74-year-old man with known Muir–Torre syndrome with confirmed MSH2 germ-line mutation, diagnosed with pleomorphic liposarcoma of the right buttock in a previous radiation field. The tumour showed loss of expression of MSH2 and MSH6 on immunohistochemistry. Results Immunohistochemistry on another pleomorphic liposar-coma in a different patient with no previous history of Muir–Torre syndrome or Lynch syndrome showed no loss of expression of mismatch repair proteins. Discussion This is the first report of Muir–Torre syndrome-associated sarcoma and the first case of post-radiation sarcoma in Lynch syndrome.

Anaplastic oligodendroglioma in an adolescent with Lynch syndrome

Lynch syndrome (hereditary non-polyposis colorectal cancer; HNPCC) is an autosomal dominant cancer predisposition syndrome with high penetrance. It is caused by heterozygous germline mutations in one of the DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6, and PMS2. Carriers are at high-risk for developing colorectal carcinomas, as well as various extracolonic malignancies. This case report describes a 15 year-old male with a confirmed germline mutation of MSH2 and early onset anaplastic oligodendroglioma. The patient's tumor showed loss of expression of MSH2 and MSH6 proteins with normal microsatellite stability. The immunohistochemical staining pattern provided strong evidence to support the inclusion of anaplastic oligodendroglioma as part of the spectrum of tumors found in Lynch syndrome.

Improving detection of Lynch syndrome using a reflex immunohistochemistry algorithm for all patients with newly diagnosed colorectal cancer.

98 Background: Identifying patients with Lynch syndrome has profound impact on the clinical care of patients and their families. Previous guidelines based on family history alone have shown low sensitivity. In our medical center, the detection rate of Lynch syndrome was <1% among colorectal cancer cases. Methods: We have developed a system-based algorithm using centralized testing by immunohistochemistry (IHC) for four mismatched repair (MMR) proteins (MLH1, MSH2, MSH6, and PMS2) as a screening method for all newly diagnosed colorectal cancer patients, followed by step wise testing of BRAF mutation, MLH1 promoter hypermethylation, +/- microsatellite instability, and germline mutation. Results: From April 1, 2011, to July 11, 2012, we have screened 116 patients. IHC detected absent expression of at least one of the MMR proteins in 18 cases. Three cases showed missing expression of MSH2/MSH6 and the presence of a germline mutation in MSH6 was confirmed in two cases. The newest case is still being investigated for germline mutation. Of the remaining 15 cases, 10 showed the presence of BRAF V600E mutation, two showed hypermethylation of the MLH1 promoter, and one showed germline MLH1 mutation. Two cases showed no BRAF V600E mutation, no MLH1 promoter hypermethylation or germline gene mutation. Overall, of 116 cases, three cases have confirmed Lynch syndrome with the detection of a germline mutation, two cases most likely have Lynch syndrome but without any detectable germline mutation of MLH1 or PMS2 using the current detecting methods. Conclusions: Our system-based screening algorithm using reflex immunohistochemistry of four MMR proteins has resulted in excellent detection rate of approximately 4% to 5% (5 out of 116 cases), consistent with the expected Lynch syndrome prevalence rate in the population. This represents a marked improvement over our previous family history-based approach in Lynch syndrome screening.

Lynch syndrome in a predominantly Afrocentric population: a clinicopathological and genetic study

We investigated the prevalence of Lynch syndrome as a hereditary cause of colon cancer in the young Jamaican colorectal cancer (CRC) population. We identified patients aged 40 years or younger in whom primary CRC was diagnosed at the University Hospital of the West Indies from January 2004 to December 2008. We reviewed the medical records and hematoxylin and eosin (H&E)-stained histopathology slides. Tumour blocks were tested for microsatellite instability (MSI). Patients with MSI-high phenotype (MSI-H) tumours had genetic counselling, after which genomic DNA was extracted from peripheral blood to test for MLH1 and MSH2 germline mutations. Patients also had pedigree mapping. There were 25 patients with CRC aged 40 years or younger with no history of hereditary colon cancer syndrome. The patients' mean age was 33 (range 21-40) years. Histopathologic review confirmed CRC in all patients; 8 of 25 (32%) showed morphologic features suggestive of MSI. We detected MSI-H in 5 of 23 (22%) tumour blocks tested. Review with H&E staining correctly identified 80% of cases positive for MSI-H. The false-positive rate and positive predictive value on H&E review was 50%. The negative predictive value of histomorphologic H&E review was 94%. Three patients were available for and had mutational analysis of DNA mismatch repair genes; 2 were positive for mutations in keeping with Lynch syndrome and 1 had MLH1 alterations of uncertain significance. All 3 met the Amsterdam criteria for hereditary nonpolyposis CRC. Thirteen percent of the population had mutations in keeping with Lynch syndrome. This prevalence is similar to that reported for white populations.

Síndrome de Lynch: selección de pacientes para el estudio genético mediante análisis de inestabilidad microsatelital e inmunohistoquímica

Selection of patients with Lynch Syndrome (LS) for a genetic study involves the application of clinical criteria. To increase the rate of identification of mutations, the use of molecular studies as Microsatellite Instability (MSI) and Immunohistochemistry (IHC) in the tumor has been proposed. To demonstrate the usefulness of MSI and IHC in the detection of mutations in patients with LS. From our Familial Colorectal Cancer Registry, families suspected of LS were selected according to Amsterdam or Bethesda clinical criteria. Screening of germline mutations of MLH1, MSH2 and MSH6 genes was performed. In addition, analysis of MSI and IHC were performed in colorectal tumors. A total of 35 families were studied (19 met Amsterdam and 16 met Bethesda criteria). Twenty one families harbored a germline alteration in MLH1, MSH2 or MSH6 (18 Amsterdam and 3 Bethesda). In these families, eighteen different alterations were found, 15 of which were mutations and 3 corresponded to variants of uncertain pathogenicity. On the other hand, 80% of the tumors showed positive microsatellite instability (27 MSI-high and 1 MSI-low), and immunohistochemical testing showed that 77% of tumors had the loss of a protein. Correlation between results of tumor molecular studies and the finding of germline nucleotide change showed that IHC and MSI predicted mutations in 81 and 100% of patients, respectively. MSI and IHC can efficiently select patients with a high probability of carrying a mutation in DNA repair genes.

Sub-cellular localization analysis of MSH6 missense mutations does not reveal an overt MSH6 nuclear transport impairment

Nearly one-third of the identified MSH6 germline mutations deal with single amino acid substitutions. For an effective genetic counselling it is necessary to clearly elucidate by functional tools the specific sub-processes underlying the mismatch repair (MMR) misfunctioning in MSH6 non-truncating mutants. Since the MMR repair pathway occurs in the nucleus, we suppose the impairment of MutSα nuclear trafficking to be a possible Lynch syndrome susceptibility causative mechanism. In the present study the MMR status of the tumour, the main clinical features of mutation carriers and population data associated to the MSH6 missense variants, were complemented with computational data about tolerability predictions and amino acid substitution conservation. The selected panel of ten potentially pathogenic MSH6 mutations was analyzed in a homologous expression system for possible deleterious effects on nucleo-cytoplasmic shuttling through the assessment of the sub-cellular localization of the corresponding mutated proteins. Localization analysis results do not reveal an apparent role of MSH6 missense mutations in nuclear import impairment and provide the first hint to exclude the MSH6 nuclear translocation sub-process as a possible causative mechanisms of MMR misfunctioning.

Germline Mutation in MSH6 Associated With Multiple Malignant Neoplasms in a Patient With Muir-Torre Syndrome

Germline Mutation in <i>MSH6</i> Associated With Multiple Malignant Neoplasms in a Patient With Muir-Torre Syndrome

Multidisciplinary approach to a case of Lynch syndrome with colorectal, ovarian, and metastatic liver carcinomas

Lynch syndrome is an autosomal dominant disorder with an estimated prevalence of 3 % of all colorectal cancers. It is attributed to germline mutations in DNA mismatch repair (MMR) genes, which confer increased susceptibility to cancers of the colorectum, endometrium, stomach, small intestine, hepatobiliary system, kidney, urinary bladder, brain, and ovary. We report a thought-provoking Lynch syndrome case with a family history and simultaneous tumors in the colon, pelvis, and liver. These findings made diagnosis and treatment complicated. However, the multidisciplinary approaches followed by a medical oncologist, gynecologist, surgeon, radiologist, and pathologist led to a favorable outcome. This patient had two primary cancers of the colon and ovary, and systemic metastases of colon cancer. The loss of MSH6 protein expression was proven by immunohistochemical examination, but the germline MSH6 mutation was not detected by DNA sequence analysis. Regarding this discrepancy, some possibilities, e.g., genomic rearrangements and epigenetic modifications, which can be missed by conventional sequence analysis, were considered. Theoretically, Lynch syndrome cases with MSH6 impairment exhibit late onset and low penetrance compared to other major cases with MLH1 or MSH6 mutations. Irinotecan hydrochloride (CPT-11) has favorable effects on MMR-deficient tumor cells with high microsatellite instability, although its clinical benefit remains controversial. In this case, the first-line chemotherapy bevacizumab + FOLFIRI regimen has been effective for over a year in the partial response state. We discuss the diagnostic, therapeutic, pathological, and molecular biological characteristics of this intriguing case, indicating the importance of family history, histological assessment, and molecular biological etiology in Lynch syndrome cases presenting a complicated phenotype.

P-0231 Occurrence of 2152 C>T –MHS2 Mutation in Brazilian Lynch Syndrome Families

ABSTRACT Introduction Lynch syndrome (LS) is an autosomal dominant cancer predisposition syndrome caused by germline mutations in one of the genes involved in mismatch repair (MMR): MLH1, MSH2, MSH6 and PMS2. It is the most common hereditary colorectal cancer (CRC) syndrome accounting for approximately 3-5% of all CRC diagnoses. Clinically, LS is characterized by early onset CRC (average age 45 years) as well as extra-colonic cancers, including endometrial, ovarian, gastric, small bowel, pancreas, hepatobiliary and brain tumors. The clinical diagnosis of LS is made when a family fulfills the Amsterdam criteria. Less strict criteria of Bethesda have been used to identify individuals at risk due to suggestive family history, early age at CRC onset or characteristic tumor histologies. MLH1 and MSH2 germline mutations account for the majority of known mutations in LS families (50-90%). To date, over 513 different DNA alterations have been reported principally in Western populations. One of the most interesting characteristics of the Brazilian population is its heterogeneity: apart from native populations, Brazil, especially Southern Brazil, has received immigrants from different countries, including an important contribution from Southern European (mainly Portuguese colonizers in the 16th century). In 1999, a novel mutation, consisting in a single base substitution of nucleotide 2152 C>T at exon 13 in MHS2, resulting in a glutamine amino acid change to a stop codon (Q718X), was describe in Portuguese Lynch families. The aim of this study is to assess the frequency of the c.2152 C>T mutation in MSH2 in Brazilian Lynch syndrome families. Methods Peripheral blood samples were obtained from 49 Lynch syndrome families after informed consent. DNA was extracted from leukocytes using the Ilustra blood genomicPrep Mini Spin kit (GE Healthcare) as described by the manufacturer. Exon 13 of the MSH2 gene was amplified by PCR and the resulting amplicons were separated on a ABI 3500 (Life Technologies) equipment. Results were analysed by the CLC Main WorkBench V6.1.1 software. Results The 2152 C>T - MHS2 mutation was identified in three (6.12%) of the 49 unrelated index cases, all of whom refer a Portuguese origin. All three families fulfilled Amsterdam criteria, and the mean of age at CRC diagnosis was 31 years. Conclusion In families meeting Amsterdam criteria, who very likely carry a germline MMR mutation, the initial genetic testing approach is often sequence analysis of the most commonly affected genes (MLH1 and MSH2), or targeted sequencing of the gene(s) whose product(s) is (are) not expressed in the colorectal tumor. The occurrence of the germline 2152 C>T - MHS2 mutation in Brazilian families at a considerable frequency, suggests that it may be a hotspot mutation in this region. Although the findings of this study should be confirmed in a larger series of patients, screening of Brazilian LS families for this mutation should be considered as an initial approach to diagnosis.

ColoSeq Provides Comprehensive Lynch and Polyposis Syndrome Mutational Analysis Using Massively Parallel Sequencing

Lynch syndrome (hereditary nonpolyposis colon cancer) and adenomatous polyposis syndromes frequently have overlapping clinical features. Current approaches for molecular genetic testing are often stepwise, taking a best-candidate gene approach with testing of additional genes if initial results are negative. We report a comprehensive assay called ColoSeq that detects all classes of mutations in Lynch and polyposis syndrome genes using targeted capture and massively parallel next-generation sequencing on the Illumina HiSeq2000 instrument. In blinded specimens and colon cancer cell lines with defined mutations, ColoSeq correctly identified 28/28 (100%) pathogenic mutations in MLH1, MSH2, MSH6, PMS2, EPCAM, APC, and MUTYH, including single nucleotide variants (SNVs), small insertions and deletions, and large copy number variants. There was 100% reproducibility of detection mutation between independent runs. The assay correctly identified 222 of 224 heterozygous SNVs (99.4%) in HapMap samples, demonstrating high sensitivity of calling all variants across each captured gene. Average coverage was greater than 320 reads per base pair when the maximum of 96 index samples with barcodes were pooled. In a specificity study of 19 control patients without cancer from different ethnic backgrounds, we did not find any pathogenic mutations but detected two variants of uncertain significance. ColoSeq offers a powerful, cost-effective means of genetic testing for Lynch and polyposis syndromes that eliminates the need for stepwise testing and multiple follow-up clinical visits.

Impact of mismatch repair (MMR) testing on colorectal cancer (CRC) oncology clinical practice.

603 Background: MMR deficiency (dMMR) has been reported in 15% of CRC, but with a lower frequency in advanced disease. Most cases are due to sporadic MLH1 promoter hypermethylation (often with BRAF mutations), with a minority reflecting germline mutations in MLH1, MSH2, PMS2, or MSH6 (Lynch Syndrome [LS]). The Revised Bethesda Guidelines (RBG) are one means of selecting individuals at risk of LS for further assessment, but will miss a proportion of cases. Methods: We screened all consenting patients for eligibility for CRC trials recruiting specific genetic aberrations, which included MMR assessment. Results: Of 314 patients, immunohistochemistry (IHC) for MMR protein expression is complete on 171. Staining was reduced/absent in 19.3% of tests, and heterogeneous in 12.1%. The dMMR rate was 6.4%. 2 dMMR patients* were identified as at risk of LS, and referred to genetics by their treating clinician before IHC results were known. However 4 other cases† were not referred, and an underlying predisposition would have been missed without this unbiased approach. 4 patients developed metastatic disease, with none experiencing a partial response to chemotherapy thus far. (Table.) Conclusions: This data is representative of a practice with a high proportion of metastatic disease. It suggests that within oncology, an unbiased screening approach for LS is preferable. Whilst the RBG detect the majority of cases, they may be underutilised as other management issues take precedence in oncology clinics. A cost-effective alternative may be the introduction of a nurse-led programme to identify cases at risk, as is being introduced at our centre. A spectrum of clinical behavior exists amongst metastatic dMMR CRC, and larger numbers will reveal if this affects therapeutic response. [Table: see text]

Novel germline MSH2 mutation in lynch syndrome patient surviving multiple cancers

Lynch syndrome (LS) individuals are predisposed to a variety of cancers, most commonly colorectal, uterine, urinary tract, ovarian, small bowel, stomach and biliary tract cancers. The risk of extracolonic manifestations appears to be highest in MSH2 mutations carriers.We present a carrier case with a novel MSH2 gene mutation that clearly demonstrates the broad extent of LS phenotypic expression and highlights several important clinical aspects. Current evidence suggests that colorectal tumors from LS patients tend to have better prognoses than their sporadic counterparts, however survival benefits for other cancers encountered in LS are unclear.In this article we describe a family with a novel protein truncating mutation of c.2388delT in the MSH2 gene, particularly focusing on one individual carrier affected with multiple primary cancers who is surviving 25 years on. Our report of multiple primary tumors occurring in the 12-25 years interval might suggest these patients do not succumb to other extracolonic cancers, provided they are regularly followed-up.

“Null Pattern” of Immunoreactivity in a Lynch Syndrome-Associated Colon Cancer Due to Germline MSH2 Mutation and Somatic MLH1 Hypermethylation

Lynch syndrome accounts for approximately 3% of newly diagnosed colorectal cancers and is caused by germline defects in DNA mismatch repair genes. Screening of patients for Lynch syndrome can be done by immunohistochemical staining for a panel of mismatch repair proteins and/or DNA testing for microsatellite instability. We describe a unique "null" immunophenotype in a Lynch syndrome associated colon cancer in a 71-year-old woman who also had a personal history of ureteral cancer and a strong family history of various malignancies. Immunohistochemical stains for MLH1, MSH2, PMS2, and MSH6 were completely negative in the tumor cells, with positive staining in stromal and inflammatory cells. Mutation analysis using peripheral blood showed a germline G587R mutation in the MSH2 gene. Further testing revealed the tumor to be positive for MLH1 promoter hypermethylation. Normal colonic mucosa adjacent to the tumor was negative for MLH1 promoter methylation. The lack of immunostaining for any of the 4 DNA mismatch repair proteins in this extremely unusual case was, therefore, related to a germline MSH2 mutation and somatic MLH1 promoter hypermethylation.

Synchronous Breast Cancers With Different Morphologic and Molecular Phenotypes Occurring in Lynch Syndrome

The increasingly widespread use of immunohistochemistry in the detection of DNA mismatch repair proteins has led to the observation of various unusual tumor types that occur in Lynch syndrome and exhibit mismatch repair protein deficiency. Understanding the clinical significance of such unusual tumors has become increasingly desirable. Here, we report a case of 2 synchronous breast cancers occurring in a 74-year-old woman who carried a deleterious germline mutation in MSH2 and who survived an endometrial and a colonic carcinoma. Both breast cancers were of lobular type with similar expression patterns for estrogen receptor, progesterone receptor, and Her2/neu. However, the 2 cancers differed in other characteristics. One tumor showed a solid alveolar histologic pattern with prominent tumor-infiltrating lymphocytes and loss of MSH2 and MSH6 protein on immunohistochemical staining. In contrast, the other tumor was of classic type with no apparent lymphocytic infiltration and no loss of mismatch repair protein. Such a case carries practical implications as it suggests that certain breast cancers may serve as tissue samples for the detection of mismatch repair deficiency in families at high risk for Lynch syndrome, thus expanding the test sample repertoire for genetic workup in these families. Furthermore, the case exemplifies the complexity of tumorigenesis in Lynch syndrome patients. The observation that, of the 2 breast cancers, increased tumor-infiltrating lymphocytes were present only in the tumor that showed mismatch repair protein abnormality is in keeping with what has been observed in the colon and other sites. Such persistent genotype-phenotype correlation across different organs affords the promise that molecular classification may allow identification of biologically distinct tumor subsets beyond the confines of the tumor's primary anatomic location.