Delineating genotype and parent-of-origin effect on the phenotype in MSH6-associated Lynch syndrome.

BACKGROUND: This study investigates the potential influence of genotype and parent-of-origin effects (POE) on the clinical manifestations of Lynch syndrome (LS) within families carrying (likely) disease-causing MSH6 germline variants. PATIENTS AND METHODS: A cohort of 1615 MSH6 variant carriers (310 LS families) was analyzed. Participants were categorized based on RNA expression and parental inheritance of the variant. Hazard ratios (HRs) were calculated using weighted Cox regression, considering external information to address ascertainment bias. The findings were cross-validated using the Prospective Lynch Syndrome Database (PLSD) for endometrial cancer (EC). RESULTS: No significant association was observed between genotype and colorectal cancer (CRC) risk (HR = 1.06, 95% confidence interval [CI]: 0.77-1.46). Patients lacking expected RNA expression exhibited a reduced risk of EC (Reference Cohort 1: HR = 0.68, 95% CI: 0.43-1.03; Reference Cohort 2: HR = 0.63, 95% CI: 0.46-0.87). However, these results could not be confirmed in the PLSD. Moreover, no association was found between POE and CRC risk (HR = 0.78, 95% CI: 0.52-1.17) or EC risk (Reference Cohort 1: HR = 0.93, 95% CI: 0.65-1.33; Reference Cohort 2: HR = 0.8, 95% CI: 0.64-1.19). DISCUSSION AND CONCLUSION: No evidence of POE was detected in MSH6 families. While RNA expression may be linked to varying risks of EC, further investigation is required to explore this observation.

Incidences of colorectal adenomas and cancers under colonoscopy surveillance suggest an accelerated "Big Bang" pathway to CRC in three of the four Lynch syndromes.

BACKGROUND: Colorectal cancers (CRCs) in the Lynch syndromes have been assumed to emerge through an accelerated adenoma-carcinoma pathway. In this model adenomas with deficient mismatch repair have an increased probability of acquiring additional cancer driver mutation(s) resulting in more rapid progression to malignancy. If this model was accurate, the success of colonoscopy in preventing CRC would be a function of the intervals between colonoscopies and mean sojourn time of detectable adenomas. Contrary to expectations, colonoscopy did not decrease incidence of CRC in the Lynch syndromes and shorter colonoscopy intervals have not been effective in reducing CRC incidence. The prospective Lynch Syndrome Database (PLSD) was designed to examine these issues in carriers of pathogenic variants of the mis-match repair (path_MMR) genes. MATERIALS AND METHODS: We examined the CRC and colorectal adenoma incidences in 3,574 path_MLH1, path_MSH2, path_MSH6 and path_PMS2 carriers subjected to regular colonoscopy with polypectomy, and considered the results based on sojourn times and stochastic probability paradigms. RESULTS: Most of the path_MMR carriers in each genetic group had no adenomas. There was no association between incidences of CRC and the presence of adenomas. There was no CRC observed in path_PMS2 carriers. CONCLUSIONS: Colonoscopy prevented CRC in path_PMS2 carriers but not in the others. Our findings are consistent with colonoscopy surveillance blocking the adenoma-carcinoma pathway by removing identified adenomas which might otherwise become CRCs. However, in the other carriers most CRCs likely arised from dMMR cells in the crypts that have an increased mutation rate with increased stochastic chaotic probabilities for mutations. Therefore, this mechanism, that may be associated with no or only a short sojourn time of MSI tumours as adenomas, could explain the findings in our previous and current reports.

A comprehensive characterization of the spectrum of MUTYH germline pathogenic variants in Latin America.

MUTYH-Associated Polyposis (MAP) is caused by biallelic pathogenic germline variants in the MUTYH gene. However, individuals harboring monoallelic MUTYH pathogenic variants in the presence of a positive family history have been reported to have a twofold increased risk of colorectal cancer (CRC) and extra colonic cancers. Our aim was to characterize the spectrum of monoallelic and biallelic germline MUTYH pathogenic variants in Latin American patients and to describe their clinical and genetic characteristics. Patients were identified from eight high-risk genetic cancer centers of five Latin American countries. Statistical analysis was performed using the two-sided P test using the Vassarstats statistical tools. Statistical significance was set at a p value ≤ 0.05. Of the 105 unrelated patients with cancer or colorectal polyposis, 84.8% and 15.2% carried pathogenic monoallelic and biallelic MUTYH variants, respectively. The most common pathogenic variants were p.Gly396Asp and p.Tyr179Cys (55% and 23%, respectively). The mean age at first diagnosis was 48.29 years (range 31-71) and 49.90 years (range 27-87) in biallelic and monoallelic MUTYH patients, respectively. CRC was the only cancer diagnosed in patients with biallelic MUTYH pathogenic variants (75%), while breast cancer (46.1%) was more common than CRC (24.7%) in individuals with monoallelic MUTYH pathogenic variants. We reported a high frequency of European founder variants in our diverse population. Some phenotypic differences from current studies were identified, such as a higher breast cancer burden in monoallelic carriers and a complete absence of extra-colon tumors in biallelic patients.

Actualización en cáncer colorrectal hereditario y su impacto en salud pública / Update on hereditary colorectal cancer and its impact on public health

Resumen Los avances en la investigación clínica, genética y molecular del cáncer colorrectal (CCR) realizados durante los últimos años han permitido su detección temprana, así como su tratamiento oportuno. Sin embargo, uno de los mayores desafíos de esta enfermedad es su naturaleza heterogénea y la participación de diversas vías moleculares en su carcinogénesis. La implementación de las tecnologías ómicas -como la genómica, la proteómica, la transcriptómica y la epigenómica- en la investigación biomédica de pacientes con CCR hereditario ha permitido identificar nuevos genes o polimorfismos de nucléotido único (SNP, por su sigla en inglés) que afectan la expresividad del cáncer. Por otra parte, las herramientas bioinformáticas han contribuido a generar nuevas hipótesis sobre el CCR, orientando el abordaje de estos pacientes hacia una medicina personalizada. Este avance científico y tecnológico tiene un impacto en la salud, tanto a nivel individual como colectivo, por lo que es importante reflexionar sobre la viabilidad de desarrollar estrategias de salud pública para la implementación de un programa integral y genético de prevención y manejo del cáncer en Perú, en especial del CCR hereditario.

Abstract Progress in clinical, genetic and molecular research of colorectal cancer (CRC) in recent years has allowed its early detection and timely and targeted treatment. However, one of the greatest challenges is the heterogeneous nature of CRC and the involvement of various molecular pathways in its carcinogenesis. The implementation of technologies known as omics -such as genomics, proteomics, transcriptomics and epigenomics- in biomedical research on patients with hereditary CRC has allowed the identification of new genes or single nucleotide polymorphisms (SNPs) that affect the expressivity of cancer. Bioinformatics tools have also contributed to generate new hypotheses about CRC, guiding the approach to these patients towards personalized medicine. This scientific and technological progress has an impact on health, both at the individual and the collective level, so it is important to reflect on the feasibility of developing public health strategies for the implementation of a comprehensive and genetic program for the prevention and treatment of cancer in Peru, especially hereditary CRC.

Identificación de cáncer colorrectal hereditario / Identification of heredity colorectal cancer: Lynch Syndrome

El síndrome de Lynch representa aproximadamente 4% de todos los tipos de cáncer colorrectal. Este síndrome se manifiesta en las familias de manera autosómica dominante y predispone a los individuos al desarrollo de cánceres temprano en la vida. El síndrome de Lynch es causado por mutaciones en la línea germinal de los genes que codifican las proteínas responsables de la reparación del daño al ADN, MLH1, MSH2, MSH6 y PMS2. La correcta historia familiar es en la actualidad el principal método para la identificación de pacientes con alto riesgo de presentar esta enfermedad, no obstante existen criterios clínicos ya establecidos. Es muy importante establecer medidas de vigilancia y monitoreo en los personas identificadas como portadoras de este síndrome, con la finalidad de ofrecer un programa de diagnóstico a sus familiares, ya que ayuda a reducir la morbimortalidad. El objetivo de esta revisión es describir los nuevos avances y conceptos sobre el síndrome de Lynch, su espectro tumoral, las características clínicas-patológicas, la correlación genotipo-fenotipo, los métodos de diagnóstico e identificación de mutaciones, así como resaltar su impacto en salud pública.

Caracterización molecular de cáncer colorrectal hereditario en Perú / Molecular characterization of hereditary colorectal cancer in Peru

Investigar molecularmente la deficiencia en los genes de reparo de DNA (MMR) asociados al síndrome de Lynch. Materiales y métodos: Realizar los análisis de inmunohistoquímica e inestabilidad de microsatélites (MSI) en 5 familias con sospecha de síndrome de Lynch de acuerdo a los criterios clínicos de Amsterdam y/o Bethesda, atendidos en el Hospital Nacional Almanzor Aguinaga Asenjo de la ciudad de Chiclayo (Lambayeque-Perú) durante 2007-2010. Resultados. La falta de expresión de las proteínas MLH1/PMS2 y una alta MSI (MSI-H) fueron observados en un paciente de sexo masculino de 60 años diagnosticado con adenocarcinoma de grado I. Adicionalmente, se realizó el análisis mutacional puntual en el gen BRAF (V600E) a fin de descartar que se trate de un caso esporádico de cáncer colorrectal. La ausencia de mutación en el gen analizado asociado a los resultados moleculares del tumor, sugiere la caracterización de este paciente como sospecha de síndrome de Lynch. Conclusiones: Es el primer estudio molecular reportado en la población peruana y demuestra la importancia del análisis molecular en familias con sospecha de cáncer colorrectal hereditario a fin de ofrecer posibilidades de vigilancia y seguimiento que han demostrado reducir la morbilidad y la mortalidad del cáncer colorrectal así como contribuir a la caracterización a nivel genética y clínica de este tipo de cáncer en la población peruana...

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. The present study contributes to the genetic and clinical characterization of the Lynch syndrome in the Peruvian population...