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Resumen: Introducción y objetivos: Una tarea frecuente en el estudio de los carcinomas colorrectales (CCR) es identificar tumores que presenten sistemas defectuosos de reparación de errores de emparejamiento en el DNA (dMMR, por sus siglas en inglés), los cuales están asociados con la inestabilidad de microsatélites. Dado que se dispone de poca información sobre estos tumores en pacientes mexicanos, nuestro objetivo fue proporcionar una descripción de su frecuencia, características clínico-patológicas y resultados, lo cual es necesario para futuros ensayos. Materiales y métodos: Se realizó una serie consecutiva de pacientes de CCR, que fueron tratados y se les dio seguimiento en un hospital de tercer nivel. Se consideraron las variables clínico-patológicas y el riesgo de cáncer hereditario o familiar. Se evaluaron las laminillas originales y la expresión de las proteínas hMLH1, hPMS2, hMSH2 y hMSH6 mediante inmunohistoquímica. Los tumores con ausencia de al menos una proteína se consideraron dMMR. Las diferencias fueron contrastadas con pruebas no paramétricas. Resultados: Ciento cuarenta y cuatro pacientes fueron incluidos, edad mediana de 65 años, 134 (93%) pacientes esporádicos, 8 (5.6%) con historia familiar de CCR y 2 (1.4%) cumplían criterios diagnósticos para cáncer de colon hereditario no polipósico, según criterios de Bethesda y Ámsterdam. Los tumores dMMR se encontraron en 39 pacientes repartidos en los 3 grupos. Fueron localmente avanzados (p

Lynch syndrome is the most common cause of inherited colorectal cancer, totaling 5 to 8% of all the cases with high susceptibility to this type of cancer and extracolonic cancer. It is related to germinal mutations taking place at mismatch repair genes. The diagnosis of Lynch syndrome is essential for both monitoring patients with this disease and detecting asymptomatic carriers, in order to establish appropriate clinical monitoring, preventive management and genetic counseling Although clinical criteria have been standardized by implementing Amsterdam I and II, as well as Bethesda guidelines, the detection rate of mutations in these genes only varies between 20% and 60%. The objective of this research was to review the state of the art regarding molecular diagnosis of Lynch syndrome; thus, a review of the literature published from 1995 to 2015 in PubMed database was performed by using the criteria “lynch syndrome molecular screening”. 19 articles were selected and reviewed, and the relevant bibliography related to such articles was also reviewed. This paper presents different approaches proposed by several researchers on molecular algorithms to improve the efficiency of Lynch syndrome diagnosis.

Se considera que el cáncer colorrectal (CCR) es un problema mundial de salud pública; es el tercer cáncer más común en hombres y el segundo en mujeres. Su distribución geográfica es variable: las tasas de incidencia son altas en países desarrollados de Europa, Norteamérica y Oceanía y bajas en países de regiones subdesarrolladas como África y Suramérica. Sin embargo, los datos de estudios recientes publicados por la Agencia Internacional de Investigaciones en Cáncer (IARC, International Agency for Research on Cancer) muestran un aumento rápido en la incidencia de CCR en los períodos 1983-1987 y 1998-2002 en países en vías de desarrollo (1), mientras que en países desarrollados la incidencia se ha estabilizado y en muchos casos ha disminuido (2). La carcinogénesis del CCR es un proceso de múltiples etapas, caracterizado por una gran inestabilidad genómica que permite la acumulación de mutaciones en protoncogenes y genes supresores de tumores, alteración en la expresión de genes y producción de proteínas no funcionales, que les confieren a las células ventajas de proliferación y aumento de la supervivencia. La inestabilidad genómica del CCR se produce por diferentes vías; entre las más importantes se encuentran: la de inestabilidad cromosómica (CIN), la de inestabilidad microsatelital (MSI) y la de metilación.

Objetivo: evaluar la utilidad de la PCR para marcadores microsatélites (PCR-STR) en la región 22q11.2 en el ADN genómico, para identificar microdeleciones en pacientes con síndrome de DiGeorge (SDG). Materiales y Métodos: se hizo un análisis de las historias clínicas de tres niñas con SDG y se investigaron deleciones en el cromosoma 22q11.2 mediante FISH y PCR-STR. Resultados: la FISH logró detectar deleciones en 22q11.2 en dos de las tres pacientes. Por su parte, por medio de la PCR-STR, se logró establecer que la paciente n.º 1 presentaba una deleción de 1,5 Mb proximal al centrómero, la segunda de mayor frecuencia en los pacientes con SDG. La deleción fue de origen paterno. Para caracterizar el defecto molecular en las otras pacientes, sería necesario acoplar estudios de cromatografía a este método, que permitan determinar el tamaño molecular de cada uno de los alelos parentales, o bien, ampliar este análisis con más microsatélites informativos ubicados en la región 22q11.2 para así definir más precisamente el tamaño de la deleción. Conclusiones: la PCR-STR en el ADN genómico es una alternativa para identificar deleciones que afectan microsatélites en la región 22q11.2 a un menor costo que la FISH y con resultados más rápidos; al mismo tiempo permite definir el origen parental y el tamaño de la microdeleción. Esta información es valiosa para identificar los genes asociados con las características clínicas del síndrome.

Colorectal cancer (CRC) has become a highly relevant condition nowadays. In this respect, advances in the understanding of its molecular basis are key for an adequate management. From the time when the adenoma-carcinoma sequence was formulated as a carcinogenesis model to this day, when, among other things, three major carcinogenic pathways have been identified, the CRC concept has evolved from that of a single disease to the notion that each CRC is a differentiated condition in itself. The suppressor or chromosome instability pathway, the mutator or microsatellite instability pathway, and the methylator or CpG island methylation pathway allow various phenotypes to be identified within CRC. Similarly, the presence of different changes in certain genes confers several behaviors on CRC from both the prognostic and responsive standpoints to specific therapies. However, this apparent complexity does help develop the clinical management of this disease through the identification of novel, more specific therapy targets, and also markers for various behaviors within the condition, which will most likely lead us to an individualized management for these patients.La importancia que está adquiriendo el cáncer colorrectal (CCR) hoy en día es importantísima. En este sentido, los avances en el conocimiento de sus bases moleculares son esenciales para su adecuado manejo. Desde la formulación del modelo de carcinogénesis de la secuencia adenoma-carcinoma hasta hoy, en que, entre otros aspectos, se han identificado tres grandes vías de carcinogénesis, el concepto de CCR ha llegado a transformarse desde el de una enfermedad única a la idea de que cada CCR es una entidad diferenciada respecto al resto de CCR. La vía supresora o de la inestabilidad cromosómica, la vía mutadora o de la inestabilidad de microsatélites, y la vía metiladora o del fenotipo metilador de islas CpG, permiten identificar diferentes fenotipos dentro del CCR. De la misma forma, la presencia de diferentes alteraciones a nivel de determinados genes confiere a los CCR distintas conductas desde el punto de vista pronóstico, o de respuesta a terapias concretas. Sin embargo la aparente complejidad, no hace sino ayudar en el desarrollo del manejo clínico de esta enfermedad a través de la identificación de nuevas dianas terapéuticas más específicas, o también de marcadores que determinan diferentes comportamientos dentro de la misma entidad, conduciéndonos, muy probablemente, a un manejo individualizado de estos pacientes.

Colorectal tumours constitute an excellent system to study carcinogenesis and the molecular events implicated in the development of cancer. Attending to the way it is transmitted, colorectal cancer may appear in one of three forms: sporadic, familial, and hereditary. The sporadic form is most common and has no familial or hereditary associated factor thus far, while familial and hereditary forms show the same inheritance pattern. Hereditary colorectal cancers develop by means of defined stages that go from lesions in the crypt of the colon through adenomas to manifest cancer. They are characterised by the accumulation of multiple mutations in tumour suppressor genes and oncogenes that affect the balance between cell proliferation and apoptosis. The colorectal carcinogenesis pathway is not unique and there are probably several ways for the initiation, development and progression of colorectal tumours.Los tumores colorrectales constituyen un excelente sistema para estudiar la carcinogénesis y los eventos moleculares involucrados en el desarrollo de un tumor. El cáncer colorrectal puede presentarse en tres formas, según su forma de transmisión: esporádico, familiar y hereditario. La forma esporádica que es la mayoritaria, no tiene hasta el momento ningún factor familiar o hereditario asociado, mientras que las formas familiares y hereditarias siguen un patrón de herencia en la propensión familiar a padecerlo. Los cánceres colorrectales hereditarios se desarrollan mediante etapas definidas que van desde lesiones en la cripta del colon a través de adenomas hasta manifestar el cáncer y se caracterizan por la acumulación de múltiples mutaciones en genes supresores de tumor y oncogenes que afectan el balance entre la proliferación celular y la apoptosis. La vía de carcinogénesis colorrectal no es una sola y probablemente existan varios caminos para el inicio, desarrollo y progresión de un tumor colorrectal.

Endometrial cancer (EC) is the second most common tumor in women with Lynch syndrome, and can be its first manifestation. It may exhibit negative immunostaining for DNA mismatch-repair proteins and/or microsatellite instability. We present the case of a woman with EC in which a MSH6 variant of unknown significance was identified. To establish the pathogenicity of the variant, the family study was extended, identifying her healthy sister as a carrier while her aunt, with EC, was not. In the latter, the histopathology of a first tumor block did not identify the pathway of carcinogenesis, but its repetition in a second tumor block suggested the possibility of it being a phenocopy. The multidisciplinary approach in the study of this family allowed a correct diagnosis of the different adenocarcinomas, adequate family genetic counselling and the correct assignment of pathogenicity to a variant in MSH6., (Copyright © 2020 Sociedad Española de Anatomía Patológica. Publicado por Elsevier España, S.L.U. All rights reserved.)

Introduction: Colorectal cancer has a high incidence in the world population. Different molecular pathways, such as chromosomal instability, microsatellite instability, and epigenetics are involved in its development. Objective: To perform molecular characterization in 44 individuals with sporadic colorectal cancer. Materials and methods: We conducted mutation analyses of the APC, KRAS, TP53 y BRAF genes using Sanger sequencing techniques; microsatellite instability was determined by capillary electrophoresis with five STR genetic markers while the methylation status of the MHL1 promotor gene was analyzed using methylation-specific PCR. Results: APC, KRAS, and TP53 genes mutation frequency was 18.1%, 25%, and 4.5%, respectively; the somatic mutations detected were located more frequently in the right colon. The frequency of microsatellite instability was 27.2% and 73.1% of the tumors had the MHL1 gene methylated while 91.6% of microsatellite instability-positive tumors had the methylated MLH1 gene. The mutation profile of microsatellite stability tumors APC, KRAS, and TP53 genes was more frequent than in the microsatellite instability-positive tumors. The methylation of the MLH1 gene was the most predominant molecular alteration. Conclusions: We identified molecular alterations in different genetic pathways of the colorectal cancer patients evaluated, which are common in the carcinogenesis of this cancer. These patients showed a different mutational profile compared to other populations. Our findings confirm the molecular heterogeneity described in the development of colorectal cancer.

Se hizo una revisión sobre el cáncer colorrectal hereditario no polipoide, el cual presenta la mayor incidencia dentro de los síndromes hereditarios que predisponen al cáncer colorrectal. Se caracteriza por manifestarse a edades tempranas, por la presencia de lesiones neoplásicas en el colon y otros órganos y por inestabilidad en microsatélites. Los microsatélites son repeticiones múltiples de 1 a 5 nucleótidos que están distribuidos por todo el genoma. Debido a su estructura repetitiva, los microsatélites son susceptibles a errores durante el proceso de replicación. La inestabilidad en microsatélites se origina como consecuencia de una deficiencia en el mecanismo posreplicativo de reparación de apareamientos erróneos. Se conocen varios genes cuyos productos están involucrados en este mecanismo y que están mutados en los tumores del cáncer colorrectal hereditario no polipoide. Para determinar inestabilidad en microsatélites en tumores de pacientes portadores se emplean diversas técnicas, entre las que se encuentran polimorfismo de conformación de cadena simple y técnicas inmunohistoquímicas.A review on nonpolipoid hereditary colorectal cancer was made. It presents the highest incidence among the heridatary syndromes predisposing to colorectal cancer. It is characterized by its appearance at early ages, the presence of neoplastic lesions in the colon and other organs, and by microsatellite instability. The microsatelites are multiple repetitions from 1 to 5 nucleotides that are distributed all around the genoma. Due to their repetitive structure, the microsatellites are susceptible to errors during the replication process. The microsatellite instabilitiy results from a deficiency in the postreplicative repair mechanism of erroneous matchings. Various genes whose products are involved in this mechanism and that are mutated in the tumors of the hereditary nonpoliposis colorectal cancer are known. Some of the different techniques used to determine microsatellite instability in tumors of carrier patients are the single chain conformation polymorphism and immunohistochemical techniques.

This review aims to present the genetic, clinical and diagnostic aspects of Lynch syndrome, as well as providing the most relevant information about genetic counseling in these patients and the current recommendations for their surveillance.

Traditionally, carcinoma classifications have been based on clinical or pathological features. However, with the development of molecular biology in recent decades, more tumors are increasingly being genetically studied and, in several of them, molecular classifications have been created (the most widely studied and used is that for breast cancer). Colon and rectum cancer are no exception. In this short review, the evolution of colon and rectum cancer molecular classification is explained and the consensus conclusions on the subject are addressed., (Copyright: © 2018 SecretarÍa de Salud.)

Background: Colorectal cancer (CRC) is an heterogeneous disease. Three carcinogenic pathways determine its molecular profile: microsatellite instability (MSI), chromosomal instability (CIN) and CpG island methylator phenotype (CIMP). Based on the new molecular classification, four consensus CRC molecular subtypes (CMS) are established, which are related to clinical, pathological and biological characteristics of the tumor., Aim: To classify Chilean patients with sporadic CRC according to the new consensus molecular subtypes of carcinogenic pathways., Material and Methods: Prospective analytical study of 53 patients with a mean age of 70 years (55% males) with CRC, operated at a private clinic, without neoadjuvant treatment. From normal and tumor tissue DNA of each patient, CIN, MSI and CIMP were analyzed. Combining these variables, tumors were classified as CMS1/MSI-immune, CMS2/canonical, CMS3/metabolic and CMS4/mesenchymal., Results: CMS1 tumors (19%) were located in the right colon, were in early stages, had MMR complex deficiencies and 67% had an activating mutation of the BRAF oncogene. CMS2 tumors (31%) were located in the left colon, had moderate differentiation, absence of vascular invasion, lymphatic and mucin. CMS3 tumors (29%) were also left-sided, with absence of vascular and lymphatic invasion, and 29% had an activating mutation of the KRAS oncogene. CMS4 tumors (21%) showed advanced stages and presence of metastases., Conclusions: This new molecular classification contributes to understanding the heterogeneity of tumors. It is possible to differentiate molecular subgroups of a single pathological diagnosis of adenocarcinoma, opening the door to personalized medicine.

Objective: To determine the presence of microsatellite instability in patients with colorectal cancer using the molecular panel Bethesda and discuss its significance in patients with suspected hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch Syndrome., Materials and Methods: We worked with samples of peripheral blood and tumor tissue of 28 patients diagnosed with colorectal cancer referred to the Laboratory of Molecular Biology of the Instituto Nacional de Enfermedades Neoplasicas (INEN), Lima, with suspected of Lynch syndrome. DNA was extracted using kits of nucleic acid extraction of peripheral blood and paraffin-embedded tumor tissue. Five microsatellite markers of Bethesda panel were amplified: BAT25, BAT26, D2S123, D5S346 and D17S250, by polymerase chain reaction. IMS analysis was performed by electrophoresis on chip in the Bioanalyzer Agilent 2100., Results: Of the patients studied, 11 had high IMS(IMS-H) and one could not be fully ranked, staying as MSI-H / IMS-L. In all cases of IMS-H both BAT26 and BAT25 were unstable. The IMS-H in these patients indicates high probability of HNPCC or Lynch syndrome; it must be contrasted with the genetic analysis of MMR genes., Conclusion: The technique allowed determine which patients have to continue with the study of system mismatch repair genes, for establish whether we facing to HNPCC or sporadic colorectal cancer.

Lynch syndrome (LS) is an autosomal-dominant inherited cancer predisposition syndrome caused by germline mutations in DNA mismatch repair genes (MLH1, MSH2, MSH6 or PMS2). Muir-Torre syndrome (MTS) is a phenotypic variant of LS that includes a predisposition to sebaceous glands tumors and keratoacanthomas. We report two patients with MTS, with more than one LS-related cancer, skin lesions, family history of cancer andmicrosatellite instability and immunohistochemistry analysis.

Background: In Chile, colorectal cancer (CRC) is often diagnosed in late stages. Thus, surgical treatment must be complemented with chemotherapy. KRAS mutations and microsatellite instability have been detected in these tumors. However, the response to treatment in patients without KRAS mutations varies and requires a better understanding., Aim: To determine the frequency and distribution of somatic point mutations in KRAS, BRAF and PIK3CA genes and microsatellite instability status (MSI) in patients with colon cancer (CC)., Material and Methods: A prospective observational study of patients undergoing surgery for colon cancer. Tumor-derived DNA was analyzed by polymerase chain reaction (PCR) for the most frequent mutations of KRAS, BRAF and PIK3CA. PCR was also used to analyze MSI., Results: Fifty-eight patients with sporadic CC were analyzed, 16 showed KRAS mutations (G12R, G12D, G12V, G13D) and out of the 42 patients that did not show any mutation, 10 had mutations in BRAF (V600E) and PIK3CA (E542K, E545D, E545K, Q546E, H1047R). BRAF mutations alone or in combination with PIK3CA mutations were observed in 27% of high MSI tumors and in 2% of tumors without instability (p < 0.049). A higher percentage of high MSI tumors were located in the right colon (p < 0.001), and showed BRAF mutation (p < 0.020)., Conclusions: The highest percentage of high MSI and BRAF mutations was observed in the right colon. Therefore, this study suggests the presence of different molecular features between right and left colon tumors that should be considered when defining the therapeutic management.

Introduction: Lynch syndrome or hereditary nonpolyposis colorectal cancer is caused by mutations in DNA repair genes, known as mismatch repair (MMR) genes, and is associated with microsatellite instability. Urothelial carcinoma of the renal pelvis is also associated with this syndrome. These genetic abnormalities have been described in sporadic forms of upper tract urothelial carcinoma (UTUC)., Material and Method: This was a descriptive study and survival analysis of a series of 80 patients with sporadic UTUC with no metastases at diagnosis (N0/Nx M0) treated exclusively with nephroureterectomy. We evaluated the expression of MMR genes (hMLH1, hPMS2, hMSH2 and hMSH6) in sections performed with tissue microarray (TMA) and their association with clinical-pathological parameters. We analyzed the prognostic value of the loss of expression of these genes in UTUC., Results: We detected no loss of MSH2 or of MSH6, but there was a loss of MLH1 in 11 cases (13.8%) and of PMS2 in 21 cases (26.3%). The expression of hMLH1 and hPMS2 were strongly associated (P<.0001), and this phenotype expression entails significant clinical implications. The loss of MLH1 was associated with a low grade (P=.02). Loss of PMS2 was associated with a lower stage (P=.05), a pushing pattern with no invasive edges (P=.008) and less angiogenesis (P=.008). The inactivation of hPMS2 or hMLH1 is an independent protective factor (HR, 0.309) and, along with the histologic grade (HR, 5.561), defines the patients' prognosis., Conclusion: In our experience, the inactivation of hPMS2 or hMLH1 is an independent marker of good prognosis and occurs in a quarter of sporadic UTUC cases. The immunohistochemical study of these patients can be used to assess the screening of hidden forms of Lynch syndrome., (Copyright © 2014 AEU. Published by Elsevier Espana. All rights reserved.)

Objective: To investigate the molecular deficiency in MMR genes associated to Lynch syndrome., Material and Methods: Immunohistochemical and microsatellite instability (MSI) analysis were performed in 5 families with suspected Lynch syndrome according to the clinical criteria, Amsterdam and/or Bethesda that had been treated at the Hospital Nacional Almanzor Aguinaga Asenjo (Lambayeque-Peru) during 2007-2010., Results: The absence of expression of MLH1/PMS2 and high MSI (MSI-H) were observed in a male patient aged 60 with adenocarcinoma grade I. In addition, the point mutational analysis was performed in BRAF (V600E) to rule that it is a sporadic case of colorectal cancer. The absence of mutation in BRAF together with the molecular analysis suggests the suspicion as a Lynch syndrome., Conclusions: It is the first molecular study reported in the Peruvian population and demonstrates the importance of molecular analysis in families with suspected hereditary colorectal cancer in order to provide possibilities of surveillance and monitoring that have been shown to reduce morbidity and mortality of colorectal cancer in the Peruvian population.

The aim of this review is to present a genetic and molecular overview of colorectal carcinogenesis (sporadic and hereditary origin) as a multistage process, where there are a number of molecular mechanisms associated with the development of colorectal cancer and genomic instability that allows the accumulation of mutations in proto-oncogenes and tumor suppressor genes, chromosomal instability, and methylation and microsatellite instability, and the involvement of altered expression of microRNAs' prognosis factors.

Background and Objetive: Hyperplastic polyposis syndrome (HPS) is an uncommon disorder characterized by hyperplastic polyps (HP) occasionally associated with serrated adenomas (SA) or mixed polyps (MP) and defined by clinical criteria (OMS/Cleveland). HPS is heterogeneous regarding the number and size of polyps, and it is associated with colorectal cáncer (CRC) and a family history. Its genetic basis is unknow. We describe individuals with HPS criteria from a series of families assessed in our Unit of Genetic Advice for colonic polyposis. Our objective is to identify the clinical characteristics of this syndrome., Patients and Methods: Retrospective study of 197 families with colonic polyposis (1998-2011), identifying patients with HPS criteria. To know the number of polyps, we took into account polypectomies and/or the histologic study of surgical samples. Polyps were classified into adenomas, serrated lesiones (HP and SA) and MP. Genetic studies revealed: microsatellite instability (MSI), MUTYH gene variants (p.Tyr165Cys, p.Gly382Asp and p.Glu396GlyfsX43) and APC gene., Results: Eighteen individuals, with a median age of 51.1 years, had criteria of HPS (11M/7F). Number of HP varied between 14 and 100 coexisting with classical adenomas, SA and MP in 14 individuals (77.8%). Localization of polyps: ascending and descending colon in 13 individuals (72.2%) and only descending colon in 5 (27.8%). A CRC was detected in 10/18 (55.6%) patients, and 3 of them had a double CRC, a family history in 3 patients (16.7%) and a history of HPS in one. IMS was not detected in 8 CRC nor in 3 adenomas studied; we detected 2/13 heterozygous mutations in the MUTYH gene (p.Gly382Asp) and one variant with an unknown biological significance in the APC gene (p.Ser926Pro)., Conclusions: The phenotypic variability of HPS difficults its identification, hence it is important to adhere to the clinical criteria established for its classification as well as to establish screening guidelines for CRC on the basis of its high incidence., (Copyright © 2012 Elsevier España, S.L. All rights reserved.)

Introduction: In 2008, colorectal cancer represented the third most commonly diagnosed tumor in Spain, and the second tumor with more deaths. Despite the new potential biomarkers in colorectal cancer, there are many challenges that need to be overcome, resulting in a need for the standardization of its determinations., Discussion: The continuous advance in tumor disease knowledge makes this review a summary of the current accepted, recommended and studied tumor markers for the diagnosis and monitoring of colorectal cancer, such as fecal markers, tissue markers and serological markers, and various prognostic markers on which there are different lines of treatment in colorectal cancer., Conclusions: Oncological guidelines recommend only a minority of tumor markers for routine use, such as the study of fecal occult blood, CEA determination in the postoperative followup, microsatellite instability to identify people susceptible to hereditary nonpolyposis colorectal cáncer, and mutation of APC in the diagnosis of familial adenomatous polyposis.

Background: 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., Aim: To demonstrate the usefulness of MSI and IHC in the detection of mutations in patients with LS., Material and Methods: 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., Results: 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., Conclusions: MSI and IHC can efficiently select patients with a high probability of carrying a mutation in DNA repair genes.

Peutz-Jeghers' syndrome is an uncommon polyposis syndrome characterized by the presence of hamartomatous polyps in the gastrointestinal tract and mucocutaneous pigmentation (especially in the oral-nasal and perianal areas and hands and feet). Inheritance is autosomal dominant, caused by a germline mutation in the STK11 (LKB1) gene. The risk of breast and gastrointestinal cancer is increased in this syndrome. Lynch's syndrome is also known as hereditary non-polyposis colorectal cancer. This syndrome is caused by a mutation in DNA mismatch repair genes and increases the risk of colon and endometrial cancer, as well as that of other neoplasms (ovary, upper urological tract, gastric, small intestine, pancreas, skin and brain). We present the case of a young woman with colorectal cancer and the coexistence of both syndromes. This association has not previously been reported in the literature., (Copyright © 2011 Elsevier España, S.L. y AEEH y AEG. All rights reserved.)

Up to 5% of all diagnosed colorectal cancers has a hereditary cuase. Colon cancer arise in younger individuals, and extracolonic tumors are also frequent. A precise understanding of main syndromes will allow the proper management of these patients, including genetic counselling, screening and prophylactic surgery., (Copyright © 2011 Elsevier España, S.L. All rights reserved.)

Introduction and Objectives: The literature on the involvement of microsatellite instability in head and neck squamous cell carcinoma shows great variability, probably due to differences in the testing methods. Using a consensus detection system, we aimed to reach a reliable estimate of microsatellite instability prevalence in a subset of head and neck squamous cell carcinoma cases., Methods: The microsatellite instabilityI status of 43 patients with previously untreated primary laryngeal squamous cell carcinomas was analyzed by a multiplex polymerase chain reaction assay including 5 mononucleotide repeat markers., Results: Thirty-six cases showed a stable phenotype or a microsatellite stable phenotype (83.7%) and 7 cases (16.3%) showed an microsatellite instability-positive phenotype. One case showed instability in 3 of 5 markers, 1 case in 2 markers and 5 cases in 1 marker. The microsatellite instability-positive and stable cases did not differ with respect to age, tumour stage, lymph node or distant metastases., Conclusions: Our data showed that a proportion of laryngeal squamous cell carcinomas are microsatellite instability positive. Knowledge of microsatellite instability patient status will allow adjusting anticancer therapy at an individual level., (Copyright © 2011 Elsevier España, S.L. All rights reserved.)

Background: Sebaceous gland tumors are a rare type of neoplasm. In some cases they have been associated with visceral tumors in patients with Muir-Torre syndrome, a hereditary form of nonpolyposis colorectal cancer. The aim of this study was to review the diagnosis and follow-up of a series of patients with sebaceous gland tumors to assess how many met the criteria for Muir-Torre syndrome., Patients and Methods: A search was performed of records from 1990 to 2005 in the database of the Department of Dermatology of the Consorcio Hospital General Universitario de Valencia in Valencia, Spain, to identify patients with sebaceous gland tumors. The biopsy material was reviewed to confirm the diagnosis. We also searched the patient histories for information suggestive of a diagnosis of Muir-Torre syndrome; when the histories were incomplete, we contacted the patients by telephone., Results: We identified 20 patients diagnosed with sebaceous gland tumors, but after reviewing the biopsy material diagnosis was only confirmed in 12. Two patients belonged to a family with a history of visceral tumors that met the clinical criteria for hereditary nonpolyposis colorectal cancer syndrome. Follow-up was not uniform in all patients and not all underwent the same tests., Conclusions: It is essential to rule out the presence of Muir-Torre syndrome in patients with sebaceous gland tumors. The use of new techniques such as immunohistochemistry or detection of microsatellite instability may help to identify families at increased risk of Muir-Torre syndrome.

Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch Syndrome is an autosomic dominant syndrome involving 596-1096 of colorectal cancer patients. Mutations in MLH1 and MSH2 genes account for most cases. These two genes participate in the DNA mismatch repair pathway. Therefore mutation carriers show microsatellite instability (MSI) in tumors. This syndrome is characterized by the early development of colorectal cancer (before 50 years) and an increased incidence of cancer in other organs. We report four siblings from a family diagnosed with HNPCC. All of them were subjected to colonic surgery for colorectal cancer Moreover, one patient developed an ampulloma after her colon surgery. The molecular-genetic analysis revealed three brothers with microsatellite instability in the tumor tissue, the absence of the MLH1 protein, and the presence of a germ line mutation localized in introm 15 of the MLH1 gene.

Background: The association between some specific human papilloma virus (HPV) types and cervix cancer is well known. However, the genetic conditions that favor the development of cervical cancer are less well known., Aim: To determine the presence of satellite instability (MSI) in preneoplastic and neoplastic lesions of the cervix and correlate these findings with HPV genotypes., Material and Methods: Biopsy samples of cervical lesions were studied. Sixteen had low grade lesions, 22 had high grade lesions and 28 had an epidermoid cancer. Viral types were identified with polymerase chain reaction, dot-blot hybridization and restriction fragment length polymorphism. MSI was determined using a panel of eight highly informative microsatellites., Results: Microsatellite instability in at least one locus was observed in 91, 56 and 69% of low grade lesions, high grade lesions and epidermoid carcinomas, respectively. MSI-High grade, MSI-Low grade instability and microsatellite stability were observed in 5, 60 and 46% of samples, respectively. Two of three samples with high grade instability had HPV 52 genotype. Other viral subtypes had frequencies that ranged from 78% to 100%, with the exception of HPV16 that was present in only 53% of samples with low grade instability., Conclusions: Two thirds of biopsy samples from cervical lesions had MSI, mechanism that can be involved in the first stages of cervical carcinogenesis. The low frequency of high grade instability, its association with HPV52 and the low frequency of HPV16 in samples with low grade instability, suggest different coadjutant mechanisms in cervical carcinogenesis.

Mutation of the mismatch repair genes MLH1 and MSH2 account for the majority of the genetic abnormalities in Lynch syndrome. Immunohistochemical detection of their protein products is becoming an increasingly common method to detect these mutations. The aim of this study was to compare the expression of MLH1 and MSH2 by immunohistochemistry and its relationship with a group of clinical and histological variables in patients with known Lynch syndrome (n=16) and in cohort of young patients (less than 50 years) who did not meet Amsterdam criteria (n=25). The mean age was 40.7 and 64% were women. Conclusive results were obtained in 40 cases (97.6%). Eighteen cases (45%) showed abnormal expression of either MLH1 (11 cases) or MSH2 (6 cases) and both stains (1 case). Alteration of the normal staining pattern was seen more commonly in patients with Lynch syndrome than in the sporadic group (68.7% vs 28%, p=0.01). A significant correlation was obtained between abnormal protein expression and microsatellite instability (MSI): normal expression: 5.9%, lack of expression: 92.3%, p<0.0001. The sensitivity and specificity of the immunohistochemical to predict MSI were 92.3% and 94.1% respectively. Immunohistochemistry and MSI results did not correlate with any histopathological parameter. In conclusion, in our experience abnormal staining of MLH and MSH correlates strongly with the presence of MSI. In addition it appears that in our population a significant proportion of young patients (< 50 years old) demonstrate alterations in the mismatch repair gene products suggesting an important role of these molecules in tumorigenesis.

Background: In patients with colorectal carcinoma, insertions or deletions of short sequences of DNA, a phenomenon called microsatellite instability, are observed., Aim: To look for microsatellite instability and mutations of MLH1 and MSH2 gene mutations in patients with colorectal carcinoma., Material and Methods: Ten patients with sporadic colorectal carcinoma and 31 patients fulfilling criteria for hereditary nonpolyposis colon cancer (HNPCC), aged 9 to 70 years, were studied. Microsatellite instability was studied in samples of tumor and peripheral blood mononuclear cell DNA. Six markers were amplified by polymerase chain reaction and capillary electrophoresis. In samples with microsatellite instability, mutations of MLH1 and MSH2 genes were studied by direct sequencing., Results: Thirty four percent of patients had microsatellite instability and among these, 76% had a high degree of instability. BAT40 marker had the higher frequency of instability. No mutations for MLH1 and MSH2 genes were observed. However a new polymorphism, C399T, was identified in exon 3 of MSH2 gene. This polymorphism was observed both in patients with sporadic colorectal carcinoma and patients with HNPCC., Conclusions: There is a high frequency of microsatellite instability among patients with colorectal cancer. A new polymorphism, not previously reported, was identified in MSH2 gene.

Background and Objective: Currently, colon cancer is a leading cause of cancer death world-wide. It progresses according to three molecular pathways, named suppressor, mutador and methylator. Microsatellite instability is a hallmark of the lack of reparation, of DNA mismatches and it characterizes a subset of colon tumors (unstable tumors, MSI). MSI-H patients (high degree of microsatellite instability) seem to share clinico-pathological differences with MSS (microsatellite stable) and MSI-L (low degree of microsatellite instability) patients. In this study, associations between high degree of microsatellite instability and pathological (location, mucinous content, differentiation grade, stages T3N0, stages II and III) and clinical features (response to chemotherapy, disease-free survival and overall survival) were evaluated., Patients and Method: 117 patients with sporadic colon cancer were classified into two populations (MSS/MSI-L and MSI-H) by using PCR and electrophoresis of seven microsatellites, according to the National Cancer Institute recommendations., Results: MSI-H tumors tended to be located in the right colon (p = 0.022) and were of mucinous histologic type (p = 0.04). No differences in disease-free survival and overall survival between group of stage II and III patients with MSS/ MSI-L and corresponding ones with MSI-H colon cancer were found (p = 0.54, p = 0.37, respectively). Conversely, MSI-H patients with stage II colon cancer had a favourable prognosis (p = 0.027). Nevertheless, response to 5-fluorouracil (5-FU) and leucovorin was similar in MSS/ MSI-L and MSI-H groups (p = 0.38)., Conclusions: MSI-H patients are characterized by certain pathological features; those MSI-H patients with a stage II seem to have a better prognosis than MSS/ MSI-L patients.