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.

Multi-ancestry genome-wide association study of kidney cancer identifies 63 susceptibility regions.

Here, in a multi-ancestry genome-wide association study meta-analysis of kidney cancer (29,020 cases and 835,670 controls), we identified 63 susceptibility regions (50 novel) containing 108 independent risk loci. In analyses stratified by subtype, 52 regions (78 loci) were associated with clear cell renal cell carcinoma (RCC) and 6 regions (7 loci) with papillary RCC. Notably, we report a variant common in African ancestry individuals ( rs7629500 ) in the 3' untranslated region of VHL, nearly tripling clear cell RCC risk (odds ratio 2.72, 95% confidence interval 2.23-3.30). In cis-expression quantitative trait locus analyses, 48 variants from 34 regions point toward 83 candidate genes. Enrichment of hypoxia-inducible factor-binding sites underscores the importance of hypoxia-related mechanisms in kidney cancer. Our results advance understanding of the genetic architecture of kidney cancer, provide clues for functional investigation and enable generation of a validated polygenic risk score with an estimated area under the curve of 0.65 (0.74 including risk factors) among European ancestry individuals.

CYP2D6 genotyping and the clinical impact on outcomes in breast cancer tamoxifen-treated patients.

Aims: To report the distribution of allele frequencies of CYP2D6 gene and to evaluate their influence on the clinical outcomes of a group of breast cancer patients receiving adjuvant tamoxifen treatment from Uruguay. Patients & methods: 199 samples were genotyped through real-time polymerase chain reaction assays. Metabolization profiles were inferred from the genotypes. Correlations were evaluated using Pearson's χ2 test. Results: Phenotype frequencies were 0.65 normal (NM), 0.30 intermediate (IM) and 0.05 poor metabolizers (PM). Similar clinical outcomes between NM and (PM + IM) patient groups (odds ratio = 1.011, 95% CI = 0.2703-3.7826; p = 0.987) were found. Conclusion: CYP2D6 allele frequencies were analyzed for the first time in a cohort from Uruguay. Results did not support any impact of CYP2D6 gene polymorphisms on clinical outcomes.

Genetic and epigenetic characteristics of patients with colorectal cancer from Uruguay.

Colorectal cancer (CRC), the 3rd most frequent cancer worldwide, affects both men and women. This pathology arises from the progressive accumulation of genetic and epigenetic alterations. In this study, KRAS, NRAS, PIK3CA, and BRAF gene mutations, mismatch repair (MMR) genes methylation profile, microsatellite instability (MSI) and CpG Island Methylator Phenotype (CIMP) status were assessed. The associations of these molecular features with clinicopathological data were also investigated. A hundred and eight unselected CRC samples and their histological and clinical data, were gathered between 2017 and 2020. The prevalence of KRAS, NRAS and BRAF gene mutations was similar to that described in other populations. 28.7% of tumors were KRAS-mutated, mostly in men, distal location, with a CIMP-negative status. BRAFV600E frequency was 6.5% and associated with MSI (p = 0.048), MLH1-methylated (p < 0.001) and CIMP-High (p < 0.001) status. We also confirmed that BRAFV600E tumors were more prevalent in older women and proximal location. A striking different result was the lack of most common variants in the PIK3CA gene. A complete absence of PIK3CA-mutated tumors in a population has not been previously reported. Among MMR genes, the only with an aberrant methylation pattern was MLH1 gene. Its frequency was 9.25%, lower than previously reported. Methylated tumors were most frequent in patients older than 70 years old and proximal tumor location. Finally, CIMP-High status was mainly observed in moderately differentiated tumors with a rate of 15.7%. Our findings were consistent with previous reports in other populations, but also showed some features unique to our cohort. This study is the first to report the analysis of a large number molecular biomarkers of CRC in Uruguay and one of the few performed in Latin-America.

Tamizaje para cáncer de mama con resonancia magnética en mujeres portadoras de mutaciones BRCA y no-BRCA / Magnetic resonance imaging breast cancer screening in women who are carriers of BRCA and non-BRCA gene mutations / Rastreamento de câncer de mama com ressonância magnética em mulheres com mutações BRCA e não BRCA

Introducción: la predisposición hereditaria causada por mutaciones patogénicas de la línea germinal (MPG) explica hasta el 10% de los cánceres de mama. Para reducir su impacto en mujeres mutadas se han propuesto diferentes estrategias, tales como las cirugías reductoras de riesgo o el screening con resonancia magnética (RM) de mamas. Métodos: en este estudio observacional retrospectivo se analizaron los registros de mujeres portadoras de MPG para evaluar las diferentes acciones tomadas luego del test genético. A las pacientes no mastectomizadas se les recomendó ingresar a un programa anual de cribado con RM y se evaluó el porcentaje de adherencia al plan, el número de biopsias efectuadas y el número de cánceres de mama detectados. Resultados: se incluyeron 134 mujeres con MPG, con una distribución en tercios iguales de los genes BRCA1, BRCA2 y genes no-BRCA. Entre las mutadas con indicación de seguimiento, 64% ingresaron al programa de cribado con RM. Las razones que llevaron a las mujeres a no ingresar al programa de seguimiento fueron: la oposición del médico tratante (53%), oposición de la paciente (38%), y falta de recursos (9%). Se realizaron seis biopsias por hallazgos en la RM entre las cuales se detectó un cáncer de mama. La incidencia de cáncer fue de 11 cada 1.000 mujeres-años de riesgo. Conclusiones: nuestro programa de seguimiento con RM de pacientes mutadas logró captar un porcentaje alto de candidatas. Una proporción significativa de las mujeres no ingresó debido la desaprobación del médico tratante o de la propia paciente. La evidencia obtenida revela una necesidad imperiosa de reforzar los programas educativos que destaquen la importancia del seguimiento con RM de las pacientes de alto riesgo en nuestro país.

Summary: Introduction: genetic propensity caused by germline pathogenic mutations explain up to 10% of breast cancer cases. Different strategies have been proposed to reduce its impact on women who are carriers of mutations, such as risk-reducing surgeries or breast magnetic resonance screening. Method: observational, retrospective study analyzing the medical records of women who are carriers of germline pathogenic mutations to assess the different measures taken after the genetic test. Non-mastectomized patients were advised to join an annual MRI screening program and the percentage of adherence to plan was evaluated, along with biopsies performed and the number of breast cancer cases detected. Results: 134 women carriers of germline pathogenic mutations were included in the study, with equal distributions in thirds for BRCA1, BRCA2 and non-BRCA genes. 64% of carriers of mutations who were subject to follow-up checkups joined the RMI screening program. The reasons why women failed to join the follow-up program were: the treating physician objected to the program (53%), the patients opposed to program (38%) and lack of resources (9%). Six biopsies were performed as a consequence of findings in the RMI, and one case of breast cancer was detected. Cancer incidence was 11 out of 1000 women - risk years. Conclusions: our RMI follow-up program for women who are carriers of mutations managed to attract a high percentage of candidates. A significant amount of women failed to join the program because of their treating physician's or their own disapproval. Evidence obtained reveals the dramatic need to reinforce educational programs that emphasize on the importance of RMI follow-up of high risk patients in our country.

Introdução: a predisposição hereditária causada por mutações germinativas patogênicas (GMP) explica até 10% dos cânceres de mama. Para reduzir seu impacto em mulheres com mutações, diferentes estratégias têm sido propostas, como cirurgias de redução de risco ou ressonância magnética (RM) das mamas. Métodos: neste estudo observacional retrospectivo, os registros de mulheres portadoras de MPG foram analisados para avaliar as diferentes ações tomadas após o teste genético. Pacientes não mastectomizadas foram recomendadas a entrar em um programa anual de triagem por ressonância magnética e foram avaliados o percentual de adesão ao plano, o número de biópsias realizadas e o número de cânceres de mama detectados. Resultados: foram incluídas 134 mulheres com MPG, com uma distribuição de terços iguais dos genes BRCA1, BRCA2 e não-BRCA. Entre as mulheres com mutações com indicação de acompanhamento, 64% entraram no programa de triagem por ressonância magnética. Os motivos que levaram as mulheres a não ingressarem ao programa de acompanhamento foram: oposição do médico assistente (53%), oposição da paciente (38%) e falta de recursos (9%). Seis biópsias foram realizadas devido a achados de ressonância magnética, entre os quais foi detectado um câncer de mama. A incidência de câncer foi de 11 por 1.000 mulheres-ano de risco. Conclusões: nosso programa de acompanhamento de ressonância magnética para pacientes com mutação conseguiu capturar uma alta porcentagem de candidatas. Uma proporção significativa de mulheres não entrou devido à falta de aprovação do médico assistente ou da própria paciente. As evidências obtidas revelam a necessidade urgente de reforçar programas educacionais que destaquem a importância do acompanhamento por RM de pacientes de alto risco no Uruguai.

A snapshot of current genetic testing practice in Lynch syndrome: The results of a representative survey of 33 Latin American existing centres/registries.

We aimed to assess the current genetics practice to manage patients with Lynch syndrome (LS) across Latin America. A Latin American LS survey was sent out to 52 centres/registries, comprising a total of 12 countries from the region. Overall, 33 centres completed the survey, of which the oldest LS registry was established in 1992 in Sao Paulo (Brazil), and the youngest this year in San Jose (Costa Rica). In total, 87% (26/30) of the participating centres/registries belonging to the nine countries are performing genetic testing. Overall, 1352 suspected families were sequenced. Pathogenic variants were identified in 34% of the families, with slightly differing distribution of variants between females and males. Path_MLH1 variants were identified in 39% of females and 50% of males (p = 0.023), while path_MSH2 were identified in 37% of females and males, followed by path_PMS2 in 11% of females and 8% of males, path_MSH6 in 13% of females and 3% of males (p < 0.001) and path_EPCAM in 0.3% of females and 2% of males. In Latin America, 9 of 12 (75%) participating countries had implemented healthcare for LS. LS screening is inconsistently applied within Latin America healthcare systems because of structural differences in the healthcare systems between the countries.

Lack of association between screening interval and cancer stage in Lynch syndrome may be accounted for by over-diagnosis; a prospective Lynch syndrome database report.

BACKGROUND: Recent epidemiological evidence shows that colorectal cancer (CRC) continues to occur in carriers of pathogenic mismatch repair (path_MMR) variants despite frequent colonoscopy surveillance in expert centres. This observation conflicts with the paradigm that removal of all visible polyps should prevent the vast majority of CRC in path_MMR carriers, provided the screening interval is sufficiently short and colonoscopic practice is optimal. METHODS: To inform the debate, we examined, in the Prospective Lynch Syndrome Database (PLSD), whether the time since last colonoscopy was associated with the pathological stage at which CRC was diagnosed during prospective surveillance. Path_MMR carriers were recruited for prospective surveillance by colonoscopy. Only variants scored by the InSiGHT Variant Interpretation Committee as class 4 and 5 (clinically actionable) were included. CRCs detected at the first planned colonoscopy, or within one year of this, were excluded as prevalent cancers. RESULTS: Stage at diagnosis and interval between last prospective surveillance colonoscopy and diagnosis were available for 209 patients with 218 CRCs, including 162 path_MLH1, 45 path_MSH2, 10 path_MSH6 and 1 path_PMS2 carriers. The numbers of cancers detected within < 1.5, 1.5-2.5, 2.5-3.5 and at > 3.5 years since last colonoscopy were 36, 93, 56 and 33, respectively. Among these, 16.7, 19.4, 9.9 and 15.1% were stage III-IV, respectively (p = 0.34). The cancers detected more than 2.5 years after the last colonoscopy were not more advanced than those diagnosed earlier (p = 0.14). CONCLUSIONS: The CRC stage and interval since last colonoscopy were not correlated, which is in conflict with the accelerated adenoma-carcinoma paradigm. We have previously reported that more frequent colonoscopy is not associated with lower incidence of CRC in path_MMR carriers as was expected. In contrast, point estimates showed a higher incidence with shorter intervals between examinations, a situation that may parallel to over-diagnosis in breast cancer screening. Our findings raise the possibility that some CRCs in path_MMR carriers may spontaneously disappear: the host immune response may not only remove CRC precursor lesions in path_MMR carriers, but may remove infiltrating cancers as well. If confirmed, our suggested interpretation will have a bearing on surveillance policy for path_MMR carriers.

From colorectal cancer pattern to the characterization of individuals at risk: Picture for genetic research in Latin America.

Colorectal cancer (CRC) is one of the most common cancers in Latin America and the Caribbean, with the highest rates reported for Uruguay, Brazil and Argentina. We provide a global snapshot of the CRC patterns, how screening is performed, and compared/contrasted to the genetic profile of Lynch syndrome (LS) in the region. From the literature, we find that only nine (20%) of the Latin America and the Caribbean countries have developed guidelines for early detection of CRC, and also with a low adherence. We describe a genetic profile of LS, including a total of 2,685 suspected families, where confirmed LS ranged from 8% in Uruguay and Argentina to 60% in Peru. Among confirmed LS, path_MLH1 variants were most commonly identified in Peru (82%), Mexico (80%), Chile (60%), and path_MSH2/EPCAM variants were most frequently identified in Colombia (80%) and Argentina (47%). Path_MSH6 and path_PMS2 variants were less common, but they showed important presence in Brazil (15%) and Chile (10%), respectively. Important differences exist at identifying LS families in Latin American countries, where the spectrum of path_MLH1 and path_MSH2 variants are those most frequently identified. Our findings have an impact on the evaluation of the patients and their relatives at risk for LS, derived from the gene affected. Although the awareness of hereditary cancer and genetic testing has improved in the last decade, it is remains deficient, with 39%-80% of the families not being identified for LS among those who actually met both the clinical criteria for LS and showed MMR deficiency.

Síndrome de Li Fraumeni: análisis clínico de un caso y revisión de la literatura / Li-Fraumeni syndrome: clinical case study and literature survey / Síndrome de Li Fraumeni: análise clínica de um caso e uma revisão da literatura

Resumen: El síndrome de Li-Fraumeni (SLF) es una enfermedad hereditaria autosómica dominante con elevada penetrancia, que se caracteriza por la aparición precoz de múltiples tumores en un individuo y una marcada agregación familiar. Aproximadamente el 70% de los pacientes que cumplen criterios clínicos para su diagnóstico son portadores de la mutación germinal del gen TP53 localizado en el cromosoma 17p13. El gen TP53 es un supresor tumoral que cumple una importante función en el control de la estabilidad genómica. Se estima que el riesgo de desarrollar cáncer es del 50 % para las mujeres a los 31 años de edad y para los hombres a los 46 años y cerca del 100 % para ambos sexos a los 70 años. El curso clínico de la enfermedad es similar que en pacientes sin SLF a excepción de la edad más temprana al diagnóstico. Presentamos el caso de una paciente de 31 años a la que se diagnostica un condrosarcoma pelviano tratado con cirugía y al momento de la recidiva, aproximadamente 8 meses después, un cáncer de mama localizado. En otro miembro de su familia se había identificado la mutación 375G>C en el gen TP53 mediante secuenciación Sanger, la cual fue detectada posteriormente en nuestra paciente. Se discuten aspectos particulares del manejo como la minimización de la exposición a la radioterapia (por reportes de tumores malignos en zonas irradiadas) y el especial manejo de la repercusión del diagnóstico a nivel de los otros integrantes de la familia.

Abstract: The Li-Fraumeni syndrome (SLF) is a highly penetrant condition with an autosomal dominant inheritance pattern, characterized by an early onset of multiple tumors in a subject and a marked familial occurrence. About 70 % of patients meeting clinical criteria for diagnosis of the disease carry the germline mutation of TP53 gene located in chromosome 17p13. TP53 is a tumor suppressor gene known for its major role in genome stability control. It has been estimated that risk of cancer development is 50 % for women at the age of 31 and for men at the age of 46 and nearly 100 % for both men and women at 70 years of age. Except at earlier ages of diagnosis, the clinical course of the disease for healthy patients and for patients suffering SLF shows similarities. We present the case of a 31-year-old patient diagnosed both with pelvic chondrosarcoma treated surgically and localized breast cancer during relapse, about 8 months later. By Sanger sequencing, mutation 375G>C had been identified in TP53 gene in another family member, and said mutation was later detected in our patient. We discuss particular aspects of treatment procedures, such as minimizing radiotherapy exposure (due to reports of malignancies in radiated areas) and the special management of diagnosis implications for other family members.

Resumo: A síndrome de Li-Fraumeni (SLF) é uma doença hereditária autorexistente dominante com pena de penetração, que caracteriza a aparição precoz de múltiplos tumores em um indivíduo e uma coletânea familiar. Aproximadamente o 70% dos pacientes com critérios clínicos para o diagnóstico em crianças portadores da mutação germinal do gen TP53 localizado no cromosoma 17p13. El gen TP53 é um tumor tumoral que cumple uma função importante no controle da estabilização genómica. Se estima que o riesgo do desengate faz dos 50% para as mulheres aos 31 anos de idade e para os 40 anos e cerca de 100% para ambos os sexos aos 70 anos. O curso clínico da doença é semelhante ao que ocorre com a SLF a exceção da doença mais tem sido diagnosticada. Presentamos o caso de um paciente de 31 años que diagnostica um paciente de pélvico com relato ao momento da recidiva, aproximadamente 8 meses depois, em um lugar de mama próximo. En otio miembro de la familia se habiocuident to the mutación 375G> C en el gen TP53 por secuenciación Sanger, a cual fue detectada em recente paciente. A discussão foi feita sobre os aspectos do tratamento com a minimização da exposição à radioterapia (por tumores malignos em zonas irradiadas) e o especial manejo da repercussão do diagnóstico a nível dos otros integrantes da familia

Aggressive mutation in a familial adenomatous polyposis syndrome family: when phenotype guides clinical surveillance.

Familial adenomatous polyposis (FAP) is an autosomal dominant genetic condition, caused by mutations in the adenomatous polyposis coli (APC) tumor suppressor gene. Desmoid tumors (DTs) are seen in 15% to 20% of FAP patients. Specific location of mutation serves as a guide to predict colonic and extra colonic manifestations and their aggressiveness. A severe FAP-phenotypic family was registered in a genetic counselling high-risk Uruguayan hereditary cancer clinic. Proband's DNA was analysed by NGS, detecting a pathogenic mutation in APC gene. All willing family members were counselled and encouraged to be tested. Here we report a kindred formed by 16 individuals with a very severe FAP phenotype. A two-base deletion mutation: c.4393_4394delAG in APC gene and a consequent premature stop codon was detected. DTs were diagnosed in 6 individuals, ranging from 2 to 25 years of age. The causes of death were diverse: gastric cancer, rectal cancer and desmoid tumor. The already described genotype-phenotype correlation has proved its worth in this family, as clinical features reflect the mutation location at 3' end of APC gene. The inheritable and lethal nature of the disease needs a tailored follow up approach in order to reduce mortality, optimize local tumor control, and preserve patients' quality of life.

Evaluation of MLH1 variants of unclear significance.

Inactivating mutations in the MLH1 gene cause the cancer predisposition Lynch syndrome, but for small coding genetic variants it is mostly unclear if they are inactivating or not. Nine such MLH1 variants have been identified in South American colorectal cancer (CRC) patients (p.Tyr97Asp, p.His112Gln, p.Pro141Ala, p.Arg265Pro, p.Asn338Ser, p.Ile501del, p.Arg575Lys, p.Lys618del, p.Leu676Pro), and evidence of pathogenicity or neutrality was not available for the majority of these variants. We therefore performed biochemical laboratory testing of the variant proteins and compared the results to protein in silico predictions on structure and conservation. Additionally, we collected all available clinical information of the families to come to a conclusion concerning their pathogenic potential and facilitate clinical diagnosis in the affected families. We provide evidence that four of the alterations are causative for Lynch syndrome, four are likely neutral and one shows compromised activity which can currently not be classified with respect to its pathogenic potential. The work demonstrates that biochemical testing, corroborated by congruent evolutionary and structural information, can serve to reliably classify uncertain variants when other data are insufficient.

A survey of the clinicopathological and molecular characteristics of patients with suspected Lynch syndrome in Latin America.

BACKGROUND: Genetic counselling and testing for Lynch syndrome (LS) have recently been introduced in several Latin America countries. We aimed to characterize the clinical, molecular and mismatch repair (MMR) variants spectrum of patients with suspected LS in Latin America. METHODS: Eleven LS hereditary cancer registries and 34 published LS databases were used to identify unrelated families that fulfilled the Amsterdam II (AMSII) criteria and/or the Bethesda guidelines or suggestive of a dominant colorectal (CRC) inheritance syndrome. RESULTS: We performed a thorough investigation of 15 countries and identified 6 countries where germline genetic testing for LS is available and 3 countries where tumor testing is used in the LS diagnosis. The spectrum of pathogenic MMR variants included MLH1 up to 54%, MSH2 up to 43%, MSH6 up to 10%, PMS2 up to 3% and EPCAM up to 0.8%. The Latin America MMR spectrum is broad with a total of 220 different variants which 80% were private and 20% were recurrent. Frequent regions included exons 11 of MLH1 (15%), exon 3 and 7 of MSH2 (17 and 15%, respectively), exon 4 of MSH6 (65%), exons 11 and 13 of PMS2 (31% and 23%, respectively). Sixteen international founder variants in MLH1, MSH2 and MSH6 were identified and 41 (19%) variants have not previously been reported, thus representing novel genetic variants in the MMR genes. The AMSII criteria was the most used clinical criteria to identify pathogenic MMR carriers although microsatellite instability, immunohistochemistry and family history are still the primary methods in several countries where no genetic testing for LS is available yet. CONCLUSION: The Latin America LS pathogenic MMR variants spectrum included new variants, frequently altered genetic regions and potential founder effects, emphasizing the relevance implementing Lynch syndrome genetic testing and counseling in all of Latin America countries.

Cáncer de mama y ovario hereditario en Uruguay: resultados del screening para mutaciones en genes de susceptibilidad por secuenciación de nueva generación / Hereditary breast and ovary cancer in Uruguay: screening results for mutations in susceptibility genes by new generation sequencing

Introducción: el cáncer de mama representa la primera causa de muerte por cáncer en mujeres de Uruguay. Se estima que cerca de 7% son causados por mutaciones en el ácido desoxirribonucleico germinal. Los costos de la secuenciación genética han descendido dramáticamente gracias a la aparición de la secuenciación de nueva generación (NGS). El cambio tecnológico abrió una nueva etapa en el estudio del cáncer hereditario en nuestro país. Objetivo: comunicar los resultados de la utilización de tecnología NGS y paneles multigénicos en familias uruguayas con alto riesgo de cáncer de mama hereditario. Pacientes y método: se secuenciaron 135 familias de alto riesgo que provenían de la consulta de consejería genética que funciona en el Grupo Colaborativo Uruguayo: Investigación de afecciones oncológicas hereditarias. Cuando la historia familiar sugería claramente un síndrome de cáncer de mama y ovario hereditario se efectuó secuenciación NGS exclusiva de los genes BRCA1 y 2; cuando el patrón familiar no configuraba claramente se utilizó un panel multigénico. Resultados: se efectuó NGS exclusiva de genes BRCA1 y 2 en 62 familias y un panel multigénico en 73 familias. Se identificaron en total 29 mutaciones patógenas (21 en genes BRCA y 8 en otros genes). Dos de ellas fueron noveles y tres pueden considerarse recurrentes en la población uruguaya. Conclusiones: este trabajo es el primero en Uruguay en reportar el resultado de esta nueva tecnología en el cáncer de mama hereditario. El hallazgo de 29 mutaciones patógenas nos ayuda a delinear el perfil mutacional de nuestro país.

Introduction: breast cancer is women's first cause of death in Uruguay. According to estimations, around 7% of cases result from germinal mutations by deoxyribonucleic acid. The cost of genetic sequencing has dramatically dropped thanks to the arrival of next-generation sequencing (NGS). This technological change opened a new era in the study of hereditary cancer in our country. Objective:to communicate the results of using NGS technology and multigenic panels in Uruguayan families with high risk of hereditary breast cancer. Method: 135 high risk families referred by the genetic counselling consultation that is provided at the Uruguayan Collaborative Group (Hereditary Oncological Conditions Research) were sequenced. When the family history clearly suggested hereditary breast and ovary cancer was a possibility, exclusive NGS sequencing was done for BRCA1 and BRCA2 genes; when the family pattern was not clear to this respect, multigenic panels were used. Results: exclusive NGS sequencing for BRCA1 and BRCA2 genes was done in 62 families, and multigenic panels were used in 73 families. 29 pathogenic mutations were identified (21 in BRCA genes and 8 in other genes). Two of them were new to the disease and three could be considered recurrent in the Uruguayan population. Conclusions:this study is the first one in Uruguay to report the results of this new technology in hereditary breast cancer. The finding of 29 pathogenic mutations contributes to outlining the mutational profile of our country.

Introdução: o câncer de mama é a primeira causa de morte por câncer em mulheres no Uruguai. Estima-se que aproximadamente 7% sejam causados por mutações no ácido desoxirribonucleico germinal. Os custos da sequenciação genética diminuíram dramaticamente graças ao aparecimento da sequenciação de nova geração (NGS). Esta nova tecnologia deu inicio a uma nueva etapa no estudo do câncer hereditário no nosso país. Objetivo: comunicar os resultados da utilização de tecnologia NGS e painéis mutagênicos em famílias uruguaias com alto risco de câncer de mama hereditário. Pacientes e método: 135 famílias de alto risco originárias do aconselhamento genético que funciona no Grupo Colaborativo Uruguaio: Pesquisa de afecções oncológicas hereditárias foram sequenciadas. Quando a história familiar sugeria uma síndrome de câncer de mama e ovário hereditários fez-se a secuenciacao NGS exclusivamente dos genes BRCA1 e 2; quando o padrão familiar não era claro foi utilizado um painel multigênico. Resultados: realizou-se NGS exclusivamente de genes BRCA1 e 2 em 62 famílias e um painel multigênico em 73 famílias. Foram identificadas 29 mutações patogênicas (21 em genes BRCA e 8 em outros genes). Duas eram novas e três podem ser consideradas como recorrentes na população uruguaia. Conclusões: este trabalho é o primeiro que apresenta os resultados desta nova tecnologia aplicada ao câncer de mama hereditário no Uruguai. O achado de 29 mutações patogênicas ajuda a definir o perfil mutacional do nosso país.

Germline Mutations in PALB2, BRCA1, and RAD51C, Which Regulate DNA Recombination Repair, in Patients With Gastric Cancer.

Up to 10% of cases of gastric cancer are familial, but so far, only mutations in CDH1 have been associated with gastric cancer risk. To identify genetic variants that affect risk for gastric cancer, we collected blood samples from 28 patients with hereditary diffuse gastric cancer (HDGC) not associated with mutations in CDH1 and performed whole-exome sequence analysis. We then analyzed sequences of candidate genes in 333 independent HDGC and non-HDGC cases. We identified 11 cases with mutations in PALB2, BRCA1, or RAD51C genes, which regulate homologous DNA recombination. We found these mutations in 2 of 31 patients with HDGC (6.5%) and 9 of 331 patients with sporadic gastric cancer (2.8%). Most of these mutations had been previously associated with other types of tumors and partially co-segregated with gastric cancer in our study. Tumors that developed in patients with these mutations had a mutation signature associated with somatic homologous recombination deficiency. Our findings indicate that defects in homologous recombination increase risk for gastric cancer.

Lynch syndrome in South America: past, present and future.

After decades of unawareness about Lynch syndrome, the medical community in South America is increasingly interested and informed. The visits and support of mentors like H. T. Lynch had been crucial to this awakening. Several countries have at least one registry with skilled personnel in genetic counseling and research. However, this only represents a very restricted resource for the region. According to the GETH, there are 27 hereditary cancer care centers in South America (21 in Brazil, 3 in Argentina, 1 in Uruguay, 1 in Chile and 1 in Peru). These registries differ in fundamental aspects of function, capabilities and funding, but are able to conduct high quality clinical, research and educational activities due to the dedication and personal effort of their members, and organizational support. More support from the governments as well as the participation of the community would boost the initiatives of people leading these groups. Meantime, the collaboration among the South American registries and the involvement of registries and leaders from developed countries will allow to maximize the efficiency in caring for affected patients and their families. The aim of this article is to describe how the knowledge of LS began to be spread in South America, how the first registries were organized and to summarize the current state of progress. In addition, we will provide an update of the clinical and molecular findings in the region.

Mutation spectrum in South American Lynch syndrome families.

BACKGROUND: Genetic counselling and testing for Lynch syndrome have recently been introduced in several South American countries, though yet not available in the public health care system. METHODS: We compiled data from publications and hereditary cancer registries to characterize the Lynch syndrome mutation spectrum in South America. In total, data from 267 families that fulfilled the Amsterdam criteria and/or the Bethesda guidelines from Argentina, Brazil, Chile, Colombia and Uruguay were included. RESULTS: Disease-predisposing mutations were identified in 37% of the families and affected MLH1 in 60% and MSH2 in 40%. Half of the mutations have not previously been reported and potential founder effects were identified in Brazil and in Colombia. CONCLUSION: The South American Lynch syndrome mutation spectrum includes multiple new mutations, identifies potential founder effects and is useful for future development of genetic testing in this continent.