No description available.

Abstract Childhood acute lymphoblastic leukemia (ALL) is the most common cancer in children. The overall survival rate has reached to 90%. However, ALL still presents a significant disease burden and is a major cause for deaths in children. Recently, both inherited germline variants related to ALL susceptibility and somatic genetic variants forming novel subgroups of ALL have been discovered. In this thesis two families with familial ALL were studied. Constitutional heterozygous microdeletion at chromosome 7p12.1p13, including IKZF1, was discovered in the first family with intellectual impairment, overgrowth, and susceptibility to childhood ALL. In the second family, constitutional chromosome translocation was revealed in two individuals with childhood ALL and, subsequently, in seven unaffected family members. The balanced reciprocal translocation t(12;14)(p13.2;q23.1) resulted in breakpoints on two genes; ETV6 on chromosome 12 and RTN1 on chromosome 14. Only a few familial and sporadic ALL cases with germline variants in either IKZF1 or ETV6 have been published, thus supporting the significant role of these constitutional variants in childhood ALL predisposition. Inherited bone marrow failure syndromes (IBMFS) may predispose to childhood leukemia, including ALL. Two unrelated patients were diagnosed with bone marrow failure without the symptoms of classical IBMFS. Neither patient had any signs of developmental delay or congenital anomalies. Exome sequencing revealed identical c.1457del(p.(Ile486fs)) mutation on the ERCC6L2 gene in both patients. A few patients with IBMFS and ERCC6L2 variants have been described in previous studies. Some of them also had congenital craniofacial anomalies and developmental delay that were not detected in the patients in this thesis. The ALL cohort study on genetic variation of mitochondrial DNA (mtDNA) included 36 children. Metabolic change where malignant cells uncouple energy production from oxidative phosphorylation (OXPHOS) is one of the established hallmarks of cancer. In the cohort in this study, 22% of patients harbored nonsynonymous variants on mtDNA in the protein-coding genes of OXPHOS enzyme complexes. The somatic non-neutral variants were found in patients with a poor prognosis cytogenetic marker. The results support the hypothesis that cancer cells harbor mtDNA variants that may affect the cell metabolism. / Tiivistelmä Akuutti lymfoblastileukemia (ALL) on lasten yleisin syöpä. Vaikka nykyisin noin 90 prosenttia paranee, ALL aiheuttaa huomattavan paljon sairastavuutta ja on merkittävä lasten kuolinsyy. Vastikään on löydetty perinnöllisiä geneettisiä muutoksia, jotka altistavat lapsuusiän ALL:lle. Tutkimuksen kohteena oli kaksi perhettä, joissa vähintään kaksi lasta on sairastunut ALL:aan. Ensimmäisessä perheessä havaittiin lapsuusiän ALL:aan sairastuneilla kehityshäiriöisillä sisaruksilla äidiltä periytyvä heterotsygoottinen deleetio kromosomissa 7p12.1p13, jossa sijaitsee IKZF1-geeni. Toisessa perheessä perinnöllinen kahden kromosomin translokaatio todettiin kahdella lapsuusiän ALL:aan sairastuneella sekä seitsemällä perheenjäsenellä. Balansoitu translokaatio t(12;14)(p13.2;q23.1) aiheuttaa katkaisukohdan ETV6-geeniin kromosomissa 12 ja RTN1-geeniin kromosomissa 14. Tähän mennessä on julkaistu vain muutamia tutkimuksia potilaista, joilla on ollut perinnöllinen muutos joko IKZF1- tai ETV6-geenissä. Näillä geeneillä oletetaan olevan tärkeä merkitys perinnöllisessä alttiudessa sairastua lapsuusiän ALL:aan. Perinnölliset luuytimen toimintahäiriöt voivat altistaa leukemialle, kuten ALL:lle. Kahdella lapsella todettiin luuytimen toimintahäiriö, mutta ei muita oireita, jotka voisivat liittyä tyypillisiin perinnöllisiin luuytimen toimintahäiriöihin. Eksomisekvensoinnissa todettiin identtinen, homotsygoottinen mutaatio c.1457del(p.(Ile486fs)) ERCC6L2-geenissä. Kirjallisuuslähteiden mukaan vain muutamalla potilaalla on todettu ERCC6L2-geenin muutoksesta johtuva luuytimen toimintahäiriö. Osalla heistä on ollut synnynnäisiä kallon ja kasvojen anomalioita sekä kehityshäiriö, jollaisia tähän tutkimukseen osallistuneilla potilailla ei todettu. Potilaskohorttitutkimuksessa tutkittiin mitokondriaalisen DNA:n (mtDNA) muutoksia ALL:aan sairastuneilla lapsilla. Syöpäsolut eivät hyödynnä mitokondrion elektroninsiirtoketjua energian tuotantoon, ja tämä aineenvaihdunnan muutos on tunnustettu syövän ominaisuus. Tutkimuksessa havaittiin, että 22 prosentilla potilaista ilmeni diagnoosivaiheessa poikkeavia mtDNA:n muutoksia, jotka olivat elektroninsiirtoketjun entsyymien alayksiköitä koodaavissa geeneissä. Muutoksia todettiin useimmiten potilailla, joilla oli leukemiasoluissa huonon ennusteen geneettinen tekijä. Havaitut muutokset voivat mahdollisesti vaikuttaa leukemiasolun energia-aineenvaihduntaan.

A doença de von Hippel-Lindau (VHL) é uma síndrome de câncer familial herdada de forma autossômica dominante que predispõe ao desenvolvimento de diversos tipos de neoplasias benignas e malignas. É causada por mutações germinativas e somáticas no gene VHL e tem uma incidência aproximada de um a cada 36.000 nascimentos. O gene VHL é um supressor tumoral e codifica a proteína VHL, a qual possui, entre outras funções, uma atividade ubiquitina-ligase, responsável pela poliubiquitinização e degradação proteassômica da subunidade alfa do fator induzido por hipóxia (HIF) na presença de oxigênio. As principais características da doença de VHL são: hemangioblastomas de sistema nervoso central (SNC), principalmente do cerebelo e medula espinhal; angiomas de retina e carcinoma renal de células claras. A probabilidade de desenvolver cada um desses tumores ao longo da vida é estimada em maior que 70%, podendo manifestar-se desde a infância até a fase adulta, principalmente entre a 2ª e 3ª décadas de vida. Classifica-se a doença de VHL conforme a ausência (tipo 1) ou presença de feocromocitoma (tipo 2). A doença do tipo 2 é causada, essencialmente, por mutações missense no gene VHL. As mutações podem ser grandes deleções (20%) ou pontuais (80%) do tipo missense, frameshift, nonsense ou em regiões de splicing. O teste genético é considerado padrão para o manejo clínico dos pacientes e dos familiares em risco, pois permite o diagnóstico e o tratamento precoce das neoplasias, melhorando assim a expectativa de vida. Técnicas de biologia molecular, como o seqüenciamento direto do DNA e o Southern blotting quantitativo, permitem a detecção de mutações germinativas em até 100% dos casos. Técnicas mais recentes, como o PCR quantitativo em tempo real e o MLPA, têm sido empregadas para uma detecção mais eficaz de grandes deleções no gene VHL. Os objetivos do presente estudo foram: (1) diagnosticar os pacientes com suspeita da doença de VHL; (2) identificar e caracterizar mutações germinativas pontuais no gene VHL nos pacientes e em seus parentes de 1º grau; (3) fornecer o aconselhamento genético pré e pós-teste. Dos 37 indivíduos com suspeita da doença de VHL, 14 pacientes de sete famílias diferentes preencheram os critérios diagnósticos. Um paciente apresentou hemangioblastoma cerebelar isolado e sete parentes de 1º grau estavam assintomáticos. Foram realizadas as técnicas de PCR, RFLP e seqüenciamento direto do DNA genômico e após clonagem. Foram identificadas quatro mutações pontuais na região codificadora do gene VHL em quatro famílias diferentes, sendo que duas delas haviam sido descritas na literatura [c.226_228delTTC (F76del), c.217C>T (Q73X)]. As outras duas mutações são descritas pela primeira vez neste estudo e afetam o sitio de splicing (IVS1-1 G>A, IVS2-1 G>C). É provável que as demais três famílias sejam portadoras de deleções germinativas no gene VHL. Em resumo, os resultados apresentados neste estudo ampliam o conhecimento da base molecular da doença de VHL e consiste na primeira pesquisa de pós-graduação produzida pelo ambulatório de aconselhamento genético do câncer do HCFMRP-USP. / Von Hippel-Lindau disease (VHL) is an autosomal dominant hereditary cancer syndrome that predisposes to the development of a variety of benign and malignant tumors. VHL is caused by germline and somatic mutations in the VHL gene and it has an incidence of approximately one in 36,000 livebirths. The VHL gene is a tumor suppressor that is translated into the VHL protein, which has many functions, mainly an ubiquitin-ligase activity, responsible for the polyubiquitylation and proteasomal degradation of the alpha subunit of the hipoxia-inducible factor (HIF) in the presence of oxygen. The main clinical features of VHL are: CNS hemangioblastomas, especially of the cerebellum and spinal cord; retinal angiomas and clear-cell renal carcinomas. The lifetime probability of developing one of these tumors is estimated at more than 70%, whichever may present since childhood until adulthood, more often during the 2nd and 3rd decades. VHL is classified into type 1 (without pheochromocytoma) and type 2 (with pheochromocytoma), the latter being mainly caused by missense mutations. VHL germline mutations may be rearrangements and large deletions (~20%) or point mutations (~80%), such as missense, frameshift, nonsense or in the splicing sites. VHL gene testing is considered standard for the clinical manegement of patients and relatives at risk, whereby it provides early diagnosis and treatment of tumors, improving their life expectancies. Molecular biology techniques such as sequencing and quantitative Southern blotting may detect virtually 100% of VHL germline mutations. More recent methods, such as quantitative real-time PCR and MLPA, have been shown to detect VHL gene gross deletions efficiently. The objectives of this study were: (1) to diagnose patients with VHL clinically; (2) to detect germline point mutations in the VHL gene in the patients and their close relatives at risk; (3) to provide pre and post-testing genetic counseling. Fourteen out of 37 patients from seven unrelated families fulfilled the VHL clinical diagnostic criteria, one patient presented a single cerebellar hemangioblastoma and seven at-risk relatives were still asymptomatic. The methods included: PCR, RFLP, genomic DNA direct sequencing and after cloning. Four germline point mutations in the coding region of the VHL gene were identified, two of whom had been described in literature [c.226_228delTTC (p.F76del), c.217C>T (p.Q73X)]. The other two mutations had not been described so far and affect the splicing sites (IVS1-1 G>A, IVS2-1 G>C). The other three families may carry gross germline deletions in the VHL gene. In conclusion, the outcome presented in this study provides with a greater knowledge of molecular basis of VHL disease and relies on the first post-graduation research carried out at the HCFMRP-USP cancer genetic counseling service.

Aproximadamente 4% das pacientes com câncer de mama têm o diagnóstico abaixo dos 36 anos. Mutação germinativa nos genes BRCA1 ou BRCA2 pode ser um dos fatores de predisposição e a identificação de pacientes carreadoras pode permitir o direcionamento do tratamento e o aconselhamento familiar para medidas de prevenção e detecção precoce. Entretanto, a maioria das pacientes apresenta câncer esporádico e fatores predisponentes são menos evidentes. Para estas pacientes, a identificação de mutações somáticas pode permitir a melhor compreensão da biologia da doença e o desenvolvimento de tratamentos dirigidos a alvos moleculares. Assim, nossos objetivos foram avaliar em pacientes jovens com câncer de mama: história familiar, hábitos de vida, mutação germinativa nos genes BRCA1 e BRCA2 e mutações somáticas no tumor. Oitenta e três pacientes diagnosticadas com câncer de mama entre 18-35 anos foram entrevistadas usando um questionário. O DNA foi extraído do sangue periférico e toda região codificadora dos genes BRCA1/2 foi sequenciada pelo método de sequenciamento de Sanger e a pesquisa de grandes deleções e inserções foi realizada por Amplificação Dependente da Ligação de Múltiplas Sondas (MLPA). Os resultados foram analisados utilizando-se os programas Mutation Surveyor v.3.20 e Chromas version 2.13 e as mutações foram caracterizadas utilizando-se os bancos de dados BIC, LOVD, LOVD-IARC, UMD e ClinVar. O sequenciamento completo do exoma foi realizado em amostras de sangue e tumor fresco congelado de oito pacientes (receptor hormonal positivo, HER2 negativo e BRCA1/2 tipo selvagem) usando Nextera Rapid Capture Enrichment e sequenciadas no Illumina HiSeq 1000. Para detecção de alterações somáticas provenientes do sequenciamento completo do exoma, foi utilizado o programa SomaticSniper (v1.0.2). Foi também analisada a presença de mutação somática no gene PIK3CA em amostras tumorais em blocos de parafina de pacientes jovens e pacientes mais idosas com câncer de mama. Além disso, foi realizada uma meta análise para avaliar se mutação somática nos cinco genes mais frequentemente mutados em câncer de mama estão associados à idade precoce. A idade mediana das 83 pacientes ao diagnóstico foi 32 anos (22-35 anos); idade mediana da menarca foi 13 anos (8-19 anos); 71,1% já passaram por pelo menos uma gestação a termo com idade mediana de 22 anos (14-34 anos); 80,7% nunca fumaram; 74,7% não ingerem bebida alcoólica regularmente; a média para índice de massa corpórea foi 25,26 (10,78-41,57). A maioria das pacientes teve diagnóstico de carcinoma ductal invasivo (89,3%), grau histológico III (49,4%), subtipo luminal (65,9%) e com expressão de Ki67 >14% (89,2%). Aproximadamente 52% das pacientes relataram história familiar para câncer de mama, ovário ou próstata. Mutações deletérias nos genes BRCA1/2 foram detectadas em 13 pacientes (BRCA1, n= 4 e BRCA2, n= 9). Uma mutação nova, que gera um códon de terminação (c.483T>A; p.Cys161Ter), foi detectada no exon 6 do gene BRCA2. O sequenciamento do exoma foi realizado em amostras de oito pacientes carreadoras de BRCA1/2 tipo selvagem e tumor subtipo luminal e revelou uma média de 39 alterações somáticas por tumor (variando entre 19-74). Foram observadas alterações com potencial driver em 53 genes, como PIK3CA, PRKD1, PRKAR1A e PIK3AP1, que codificam proteínas tirosina quinase ou proteínas envolvidas na regulação de proteínas quinases; e no gene POLD1, que codifica a subunidade catalítica da polimerase delta, com papel na replicação e reparo do DNA. Em uma meta análise observamos que a mutação somática no gene PIK3CA é relativamente frequente em pacientes jovens e idosas. Concluindo, mais de 15% das pacientes jovens são carreadoras de mutação deletéria nos genes BRCA1 ou BRCA2. Em pacientes com câncer esporádico foram encontradas mutações somáticas em genes que codificam proteínas tirosina quinase ou proteínas envolvidas em reparo de DNA. Em consonância com o observado em tumores de pacientes mais idosas, mutação somática no gene PIK3CA é relativamente frequente em tumores de pacientes jovens / Approximately 4% of the breast cancer patients have their diagnosis under the age of 36 years and germline mutations in BRCA1 or BRCA2 genes is one of the predisposing factors. Identification of patients who are mutation carriers may contribute for the adoption of targeted therapies and for genetic counseling of their family members for early detection or preventive measures. However, most patients present with sporadic cancer where predisposing factors are less understood. In the latter group of patients, the identification of somatic mutations may contribute to a better understanding of the biology of the disease and to the development of molecular targeted therapies. Therefore, our goals were to characterize early onset breast cancer patients for family history, lifestyle, germline mutations in BRCA1 and BRCA2 genes and somatic mutations. Eighty-three breast cancer patients aged 18-35 years were interviewed using a questionnaire. DNA was extracted from peripheral blood and all coding regions of BRCA1/2 genes were screened by Sanger sequencing and large deletions and insertions were examined by Multiplex Ligation-Dependent Probe Amplification (MLPA). Results were analyzed through Mutation Surveyor v.3.20 and Chromas version 2.13 and searched in BIC Database, LOVD, LOVD-IARC, UMD and ClinVar. Whole exome sequencing was performed in blood and fresh-frozen tumor samples from eight patients (hormone receptor positive, HER2 negative and BRCA1/2 wild type) using Nextera Rapid Capture Enrichment in an Illumina HiSeq 1000. To detect somatic SNVs from whole exome sequencing data, SomaticSniper (v1.0.2) was used. Somatic mutation in PIK3CA gene was then searched in Formaldehyde Fixed-Paraffin Embedded samples from another group of young and older breast cancer patients. In addition, a metaanalysis was performed to evaluate whether somatic mutations in the five genes most frequently mutated in breast cancer patients were associated with an early age onset. Median age of 83 patients at diagnosis was 32 years (22-35y), median age of menarche was 13 years (8-19y); 71.1% patients had at least one born child, median age of first pregnancy was 22 years (14-34y); 80.7% were never smokers; 74.7% reported no regular alcoholic drinking; median body mass index was 25.26 (10.78-41.57). Most patients presented with invasive ductal carcinoma (89.3%), histological grade III (49.4%), luminal subtype (65.9%) and Ki67 expression > 14% (89.2). Approximately 52% of the patients reported a positive family history for breast, ovarian or prostate cancer. Deleterious mutations in BRCA1/2 genes ware detected in 13 patients (BRCA1, n= 4 and BRCA2, n= 9). One novel mutation was detected in BRCA1 gene: a stop codon in exon 6 (c.483T > A; p.Cys161Ter). Exome sequencing was evaluated in eight luminal tumors fromBRCA1/2 wild type patients and a median of 39 somatic alterations/tumor was detected, varying from 17 to 74. Potential driver alterations were detected in 53 genes, such as PIK3CA, PRKD1, PRKAR1A and PIK3AP1, that encode tyrosine kinase proteins or proteins involved in tyrosine kinases regulation; and POLD1 gene, that encodes the catalytic subunit of DNA polymerase delta which plays a critical role in DNA replication and repair. A Meta-analysis showed that somatic mutation in PIK3CA gene was frequently detected in both young and older patients. In conclusion, more than 15% of the young breast cancer patients are BRCA1 or BRCA2 mutation carriers. In patients with sporadic cancer somatic mutations were found in genes that encode tyrosine kinase proteins or are involved in the DNA repair. In agreement with what was observed in tumors from older patients, somatic mutation in PIK3CA gene is relatively frequent in tumors from young patients

Abstract Two major genes are involved in hereditary predisposition to breast and ovarian cancer – BRCA1 and BRCA2. However, germline mutations in these tumor suppressors account for a maximum 20% of the familial breast cancer cases. A significant portion of the genes predisposing to this disease is unknown and therefore needs to be discovered. The aim of this study was to identify novel breast cancer susceptibility genes from the interweaving BRCA/Fanconi anemia (FA) pathway. Five candidate genes – MERIT40, ABRAXAS, BRIP1, CHK1, and FANCA – were screened for mutations by utilizing conformation-sensitive gel electrophoresis and sequencing, or with multiplex ligation-dependent probe amplification in blood DNA samples of Finnish familial breast cancer patients. Investigation of the MERIT40 gene revealed novel nucleotide changes, being the first report on mutation screening of this gene. None of the observed alterations, however, appeared to be disease related, suggesting that germline mutations in MERIT40 are rare or absent in breast cancer patients. A missense alteration (c.1082G>A, leading to Arg361Gln) was identified in ABRAXAS in 3 out of 125 Northern Finnish breast cancer families (2.4%), but not in any of the 867 healthy controls. The prevalence of the mutation between familial and control cases was statistically significantly different (p=0.002). ABRAXAS c.1082G>A appears to have pathological significance based on its exclusive occurrence in cancer cases, evolutionary conservation, disruption of a putative nuclear localization signal, reduced nuclear localization of the protein, and defective accumulation at DNA damage sites. The BRIP1 (FANCJ) and CHK1 genes were screened for large genomic rearrangements, but no abnormalities were detected, ruling out a significant contribution to breast cancer susceptibility in the Northern Finnish population. A novel large heterozygous deletion was identified in the FANCA gene in one out of 100 breast cancer families, removing the promoter and the first 12 exons. The deletion allele was not present in the tested controls, suggesting that it might contribute to breast cancer susceptibility. This is the first report on the association of a large-size germline deletion in a gene acting in the upstream part of the FA signaling pathway with familial breast cancer. / Tiivistelmä BRCA1 ja BRCA2 ovat kaksi tärkeintä perinnöllisen rinta- ja munasarjasyövän alttiusgeeniä. Niissä esiintyvät ituradan muutokset selittävät kuitenkin vain noin 20 % familiaalisista rintasyöpätapauksista. Suurin osa alttiusgeeneistä on edelleen tunnistamatta ja näitä tekijöitä etsitään aktiivisesti. Tämän tutkimuksen tarkoituksena on ollut tunnistaa uusia alttiustekijöitä toisiinsa läheisesti liittyviltä BRCA/Fanconin anemia (FA) signaalinsiirtoreiteiltä. Viisi kandidaattigeeniä - MERIT40, ABRAXAS, BRIP1, CHK1 ja FANCA – kartoitettiin mutaatioiden suhteen suomalaisissa rintasyöpäperheissä käyttämällä konformaatiosensitiivistä geelielektroforeesia ja sekvensointia, tai multiplex ligation-dependent probe amplification- menetelmää. MERIT40-geenissä havaittiin useita aikaisemmin raportoimattomia nukleotidimuutoksia, mutta yhdenkään niistä ei havaittu liittyvän rintasyöpäalttiuteen. MERIT40-geenimuutosten mahdollista yhteyttä rintasyöpäalttiuteen ei ole tutkittu aikaisemmin. ABRAXAS-geenissä havaittiin missense-mutaatio (c.1082G>A, joka johtaa Arg361Gln aminohappokorvautumiseen) kolmessa pohjoissuomalaisessa rintasyöpäperheessä (3/125, 2.4 %). Muutosta ei havaittu terveissä kontrolleissa (N=867), ja ero mutaation esiintyvyydessä familiaalisten rintasyöpätapausten ja terveiden kontrollien välillä oli tilastollisesti merkitsevä (p=0.002). ABRAXAS c.1082G>A-muutos on todennäköisesti patogeeninen, sillä kyseinen aminohappopaikka on evolutiivisesti konservoitunut ja sijaitsee todennäköisellä tumaanohjaussignaalialueella. Funktionaaliset kokeet osoittivat, että mutatoitunut proteiinituote lokalisoitui villityypin proteiinia heikommin tumaan ja sen ohjautuminen DNA-vaurioalueille oli puutteellista. BRIP1- (FANCJ) ja CHK1-geeneistä etsittiin laajoja genomisia uudelleenjärjestelyjä, mutta niitä ei havaittu. Näin ollen kyseisillä muutoksilla ei ole merkittävää roolia perinnöllisessä rintasyöpäalttiudessa suomalaisessa väestössä. FANCA-geenissä havaittiin laaja heterotsygoottinen deleetio yhdessä tutkitusta 100 rintasyöpäperheestä. Deleetio poistaa geenin promoottorialueen lisäksi sen 12 ensimmäistä eksonia. Deleetioalleelia ei havaittu terveissä kontrolleissa, joten se mahdollisesti liittyy perinnölliseen rintasyöpäalttiuteen. Tutkimus on ensimmäinen, jossa raportoidaan laaja genominen deleetio FA-signaalinsiirtoreitin ylävirran geenissä familiaalisessa rintasyövässä.

No description available.

In this thesis, I argue that the treatment/enhancement distinction that is central to the ethical debate concerning germline genome editing and CRISPR is too vague to be ethically and normatively guiding. The problem of vagueness is twofold, being both a semantic and epistemic issue. This vagueness creates borderline cases, cases that cannot be properly defined as either treatment or enhancement, I call this The Borderline Cases Argument. These borderline cases enable a slippery slope towards eugenic practices, radical enhancement and dangerous applications of CRISPR. The distinction therefore fails to be action guiding as it cannot distinguish treatment from enhancement as well as failing to correspond to what is genuinely morally problematic with germline genome editing and not, I call this The Argument of Missing the Point. In using the treatment/enhancement distinction we therefore risk losing control over how CRISPR is used and for what purposes.

La inestabilidad de microatélites (MSI) está presente en diferentes tipos tumorales. Generalmente se explica por metilación del promotor de MLH1 o mutaciones germinales en los genes de reparación mismatch repair (MMR) del ADN, causando el conocido síndrome de Lynch. Recientemente, con el cribado universal se ha dado a conocer que un gran porcentaje de tumores con sospecha de síndrome de Lynch, no presentan estas mutaciones. Hasta la fecha, la hipótesis más aceptada para explicar este fenómeno conocido como síndrome Lynch-like, es la doble inactivación de estos genes a nivel somático. Aun así, estos pacientes presentan cáncer colorectal y otros tumores a edades tempranas y en muchos casos, se acompaña de una historia familiar de cáncer colorectal, que sugiere un origen hereditario. Objetivos: Elucitar las bases moleculares responsables de la pérdida de función del sistema MMR en casos de sospecha de Síndrome de Lycnh sin mutaciones germinales en estos genes. Estudio germinal: Identificar nuevas mutaciones germinales en genes reparadores del ADN que puedan estar implicadas en el desarrollo de inestabilidad de microsatélites. Estudio somático: Realizar una caracterización molecular de los tumores con MSI para identificar los eventos moleculares que pueden impactar el comportamiento tumoral y el manejo clínico. Materiales y métodos: Se analizó el exoma germinal de 100 muestras de pacientes Lynch-like y 30 Lynch. Adicionalmente se secuenciaron 37 tumores Lynch-like, 25 Lynch y se utilizó la información de 31 MSI/BRAF del TCGA. Las muestras fueron secuenciadas en Illumina HiSeq y analizadas en un High-performance computer siguiendo los estándares del Yale Center for Genome Analysis (YCGA). Resultados: Estudio germinal: Entre los Lynch-like encontramos 7 Lynch no identificados previamente. El 50% del MSI detectado en Lynch-like podía explicarse por dobles inactivación de los mismos a nivel somático. Además entre los Lynch-like encontramos 15 variantes germinales patogénicas que podían explicar la inestabilidad genética. Dos de ellas con inactivación del otro alelo a nivel somático. Además demostramos que la inactivación de un solo alelo es suficiente para tener un fenotipo deficiente. Estudio somático: no todos los tumores clasificados como MSI por MSI-PCR son presentan esta inestabilidad a nivel global. Al analizar diferentes tumores MSI descubrimos dos clústeres bien diferenciados en base a los perfiles mutacionales detectados. Buscamos mutaciones en genes reparadores y de predisposición al cáncer que pudieran estar marcando esas diferencias en las signatures. Discusión y conclusiones: Estudio germinal: Este estudio confirma el enriquecimiento existente en variantes germinales en los genes reparadores del ADN en pacientes con Síndrome Lynch-like. Variantes en estos genes, conferirían una deficiencia media heredada que promovería y podría inducir una inestabilidad genómica con el paso del tiempo. LA identificación de la variante en RECQL5 como potencial mutación asociada a un fenotipo de cáncer colorrectal familiar. Lynch-like es un grupo heterogéneo a nivel genético, con la característica común de ser MSI. Los tumores Lynch-like pueden ser causados por doble inactivación somática u otros defectos en otros genes reparadores. Además, el grupo incluye Lynch no identificados por los métodos de detección actuales. Estudio somático: Este estudio proporciona un valorable nueva perspectiva en los tumores con deficiencia en el sistema MMR. Muestra la correlación entre los diferentes niveles de MSI global y los perfiles mutacionales y clínicos, lo cual puede tener grandes implicaciones a nivel de diagnóstico y tratamiento de los pacientes.

Mutations in the BRCA1 and BRCA2 genes are known risk factors and drivers of breast and ovarian cancers. So far, few studies have been focused on understanding the differences in transcriptome and functional landscapes associated with the disease (breast vs. ovarian cancers), gene (BRCA1 vs. BRCA2), and mutation type (germline vs. somatic). In this study, we were aimed at systemic evaluation of the association of BRCA1 and BRCA2 germline and somatic mutations with gene expression, disease clinical features, outcome, and treatment. We performed BRCA1/2 mutation centered RNA-seq data analysis of breast and ovarian cancers from the TCGA repository using transcriptome and phenotype 'portrayal' with multi-layer self-organizing maps and functional annotation. The results revealed considerable differences in BRCA1- and BRCA2-dependent transcriptome landscapes in the studied cancers. Furthermore, our data indicated that somatic and germline mutations for both genes are characterized by deregulation of different biological functions and differential associations with phenotype characteristics and poly(ADP-ribose) polymerase (PARP)-inhibitor gene signatures. Overall, this study demonstrates considerable variation in transcriptomic landscapes of breast and ovarian cancers associated with the affected gene (BRCA1 vs. BRCA2), as well as the mutation type (somatic vs. germline). These results warrant further investigations with larger groups of mutation carriers aimed at refining the understanding of molecular mechanisms of breast and ovarian cancers.

No description available.