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BACKGROUND: Hereditary leiomyomatosis and renal cell cancer syndrome is a rare autosomal dominant hereditary syndrome. Previously, we published the largest cohort of FH mutation carriers in Spain and observed a highly recurrent missense heterozygous variant, FH(NM_000143.4):c.1118A > G p.(Asn373Ser), in 104 individuals from 31 apparently unrelated families. Here, we aimed to establish its founder effect and characterize the associated clinical phenotype. RESULTS: Haplotype analysis confirmed that families shared a common haplotype (32/38 markers) spanning 0.61-0.82 Mb, indicating this recurrent variant was inherited from a founder ancestor. Cutaneous and uterine leiomyomatosis were diagnosed in 64.6% (64/99) and 98% (50/51) of patients, respectively, and renal cell cancer was present in 10.4% (10/96). The pathogenic FH_c.1118A > G variant is a Spanish founder mutation that originated 12-26 generations ago. We estimate that the variant may have appeared between 1370 and 1720. Individuals carrying this founder mutation had similar frequency of renal cell cancer and a higher frequency of renal cysts and leiomyomas than those in other cohorts of this syndrome. CONCLUSIONS: In the Spanish province of Alicante there is a high prevalence of HLRCC because of the founder mutation FH c.1118A > G; p.(Asn373Ser). The characterization of founder mutations provides accurate and specific information regarding their penetrance and expressivity. In individuals with suspected HLRCC from the province of Alicante, genetic testing by direct analysis of the founder FH c.1118A > G; p.(Asn373Ser) mutation may be a faster and more efficient diagnostic tool compared with complete gene sequencing.
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Carcinoma de Células Renais , Neoplasias Renais , Leiomiomatose , Síndromes Neoplásicas Hereditárias , Neoplasias Cutâneas , Neoplasias Uterinas , Feminino , Humanos , Leiomiomatose/genética , Leiomiomatose/patologia , Neoplasias Renais/genética , Neoplasias Cutâneas/patologia , Mutação/genética , SíndromeRESUMO
Clinical and familial factors predict psychological distress after genetic testing for cancer susceptibility. However, the contribution of an individual's psychological background to such distress is unclear. This study aims to analyze the psychological impact of genetic testing and to identify the profile of individuals at higher risk. This is a longitudinal multicenter study of individuals undergoing genetic testing for cancer susceptibility. Demographic, clinical, genetic, familial, and psychological (personality types, cancer worry) characteristics were assessed by validated questionnaires the day of genetic testing. Distress, uncertainty, and positive experience perception (MICRA scale) were evaluated at the results disclosure visit, and 3 and 12 months afterwards. Multivariate analysis was performed. A total of 714 individuals were included. A high neuroticism score, high baseline cancer worry, and a positive genetic test result were independently associated with higher psychological impact (p-value < 0.05). The highest risk profile (10% of the cohort) included women with high level of neuroticism and a positive result. Uncertainty was mainly associated with a high level of neuroticism, regardless of the genetic test result. A holistic approach to personalized germline genetic counseling should include the assessment of personality dimensions.
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Neoplasias , Estresse Psicológico , Humanos , Feminino , Estresse Psicológico/psicologia , Testes Genéticos , Aconselhamento Genético/psicologia , Neoplasias/genética , Ansiedade/psicologiaRESUMO
The mechanisms triggering metastasis in pheochromocytoma/paraganglioma are unknown, hindering therapeutic options for patients with metastatic tumors (mPPGL). Herein we show by genomic profiling of a large cohort of mPPGLs that high mutational load, microsatellite instability and somatic copy-number alteration burden are associated with ATRX/TERT alterations and are suitable prognostic markers. Transcriptomic analysis defines the signaling networks involved in the acquisition of metastatic competence and establishes a gene signature related to mPPGLs, highlighting CDK1 as an additional mPPGL marker. Immunogenomics accompanied by immunohistochemistry identifies a heterogeneous ecosystem at the tumor microenvironment level, linked to the genomic subtype and tumor behavior. Specifically, we define a general immunosuppressive microenvironment in mPPGLs, the exception being PD-L1 expressing MAML3-related tumors. Our study reveals canonical markers for risk of metastasis, and suggests the usefulness of including immune parameters in clinical management for PPGL prognostication and identification of patients who might benefit from immunotherapy.
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Neoplasias das Glândulas Suprarrenais , Segunda Neoplasia Primária , Paraganglioma , Feocromocitoma , Humanos , Neoplasias das Glândulas Suprarrenais/genética , Genômica , Paraganglioma/genética , Paraganglioma/imunologia , Feocromocitoma/genética , Feocromocitoma/imunologia , Microambiente Tumoral/genéticaRESUMO
BACKGROUND/OBJECTIVES: Exome sequencing may identify pathogenic variants unrelated with the purpose of the analysis. We investigated the frequency of secondary and incidental findings (SF/IF) in cancer susceptibility genes (CSG), their clinical actionability and the psychological impact in individuals with an SF/IF (cases) compared with individuals tested due to their cancer history (controls). METHODS: This study analysed 533 exomes ordered for non-cancer conditions. Medical records were reviewed for clinical actionability of SF/IF. Psychological impact was analysed using the Multidimensional Impact of Cancer Risk Assessment (MICRA) scale and compared between cases and controls with a propensity score weighting method. RESULTS: The frequency of SF/IF in CSG was 2.1% (95% CI 1.1% to 3.8%): three BRCA2, three PMS2, two SDHB, and one each in BRCA1, MLH1 and RAD51C. Among the relatives, 18 were carriers. Twenty enrolled for surveillance, and a neoplasm was diagnosed in 20%: three paragangliomas and one breast cancer. Cases presented higher MICRA mean scores than controls (21.3 vs 16.2 in MICRA total score, 6.3 vs 4.2 in the distress subscale, and 8.3 vs 6.6 in the uncertainty subscale; all p<0.001). CONCLUSION: SF/IF in CSG were identified in 2.1% of patients. Despite a numerically higher psychological impact, the identification of SF/IF allowed early detection and cancer prevention in families without cancer history.
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Neoplasias da Mama , Predisposição Genética para Doença , Humanos , Feminino , Sequenciamento do Exoma , Achados Incidentais , Neoplasias da Mama/genética , Genes BRCA2RESUMO
Rothmund-Thomson syndrome, a heterogeneous genodermatosis with autosomal recessive hereditary pattern, is an uncommon cancer susceptibility genetic syndrome. To date, only 400 cases have been reported in the literature, and the severity of the features varies among individuals with the condition. Here, we describe a 55-year-old male who had been diagnosed with Bloom Syndrome during childhood due to the suggestive physical features such as short stature, chronic facial erythema, poikiloderma in face and extremities, microtia and microcephaly. However, the genetic test demonstrated that the patient carried two pathogenic variants resulting in compound heterozygous in the RECQL4 gene (c.2269C>T and c.2547_2548delGT). He subsequently developed a calcaneal osteosarcoma, which was successfully treated, and has currently been oncologic disease-free for 3 years.
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Síndrome de Bloom , Síndrome de Rothmund-Thomson , Masculino , Humanos , Pessoa de Meia-Idade , Síndrome de Rothmund-Thomson/diagnóstico , Síndrome de Rothmund-Thomson/genética , RecQ Helicases/genética , Síndrome de Bloom/diagnóstico , Síndrome de Bloom/genéticaRESUMO
There is a growing need for systems that efficiently support the work of medical teams at the precision-oncology point of care. Here, we present the implementation of the Molecular Tumor Board Portal (MTBP), an academic clinical decision support system developed under the umbrella of Cancer Core Europe that creates a unified legal, scientific and technological platform to share and harness next-generation sequencing data. Automating the interpretation and reporting of sequencing results decrease the need for time-consuming manual procedures that are prone to errors. The adoption of an expert-agreed process to systematically link tumor molecular profiles with clinical actions promotes consistent decision-making and structured data capture across the connected centers. The use of information-rich patient reports with interactive content facilitates collaborative discussion of complex cases during virtual molecular tumor board meetings. Overall, streamlined digital systems like the MTBP are crucial to better address the challenges brought by precision oncology and accelerate the use of emerging biomarkers.
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Sistemas de Apoio a Decisões Clínicas , Neoplasias , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Oncologia/métodos , Neoplasias/diagnóstico , Medicina de Precisão/métodosRESUMO
Introduction: The percentage of patients diagnosed with pheochromocytoma and paraganglioma (altogether PPGL) carrying known germline mutations in one of the over fifteen susceptibility genes identified to date has dramatically increased during the last two decades, accounting for up to 35-40% of PPGL patients. Moreover, the application of NGS to the diagnosis of PPGL detects unexpected co-occurrences of pathogenic allelic variants in different susceptibility genes. Methods: Herein we uncover several cases with dual mutations in NF1 and other PPGL genes by targeted sequencing. We studied the molecular characteristics of the tumours with co-occurrent mutations, using omic tools to gain insight into the role of these events in tumour development. Results: Amongst 23 patients carrying germline NF1 mutations, targeted sequencing revealed additional pathogenic germline variants in DLST (n=1) and MDH2 (n=2), and two somatic mutations in H3-3A and PRKAR1A. Three additional patients, with somatic mutations in NF1 were found carrying germline pathogenic mutations in SDHB or DLST, and a somatic truncating mutation in ATRX. Two of the cases with dual germline mutations showed multiple pheochromocytomas or extra-adrenal paragangliomas - an extremely rare clinical finding in NF1 patients. Transcriptional and methylation profiling and metabolite assessment showed an "intermediate signature" to suggest that both variants had a pathological role in tumour development. Discussion: In conclusion, mutations affecting genes involved in different pathways (pseudohypoxic and receptor tyrosine kinase signalling) co-occurring in the same patient could provide a selective advantage for the development of PPGL, and explain the variable expressivity and incomplete penetrance observed in some patients.
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Neoplasias das Glândulas Suprarrenais , Paraganglioma , Feocromocitoma , Humanos , Feocromocitoma/patologia , Predisposição Genética para Doença , Paraganglioma/patologia , Mutação , Neoplasias das Glândulas Suprarrenais/diagnósticoRESUMO
BACKGROUND & AIMS: Colonoscopy reduces colorectal cancer (CRC) incidence and mortality in Lynch syndrome (LS) carriers. However, a high incidence of postcolonoscopy CRC (PCCRC) has been reported. Colonoscopy is highly dependent on endoscopist skill and is subject to quality variability. We aimed to evaluate the impact of key colonoscopy quality indicators on adenoma detection and prevention of PCCRC in LS. METHODS: We conducted a multicenter study focused on LS carriers without previous CRC undergoing colonoscopy surveillance (n = 893). Incident colorectal neoplasia during surveillance and quality indicators of all colonoscopies were analyzed. We performed an emulated target trial comparing the results from the first and second surveillance colonoscopies to assess the effect of colonoscopy quality indicators on adenoma detection and PCCRC incidence. Risk analyses were conducted using a multivariable logistic regression model. RESULTS: The 10-year cumulative incidence of adenoma and PCCRC was 60.6% (95% CI, 55.5%-65.2%) and 7.9% (95% CI, 5.2%-10.6%), respectively. Adequate bowel preparation (odds ratio [OR], 2.07; 95% CI, 1.06-4.3), complete colonoscopies (20% vs 0%; P = .01), and pan-chromoendoscopy use (OR, 2.14; 95% CI, 1.15-3.95) were associated with significant improvement in adenoma detection. PCCRC risk was significantly lower when colonoscopies were performed during a time interval of less than every 3 years (OR, 0.35; 95% CI, 0.14-0.97). We observed a consistent but not significant reduction in PCCRC risk for a previous complete examination (OR, 0.16; 95% CI, 0.03-1.28), adequate bowel preparation (OR, 0.64; 95% CI, 0.17-3.24), or previous use of high-definition colonoscopy (OR, 0.37; 95% CI, 0.02-2.33). CONCLUSIONS: Complete colonoscopies with adequate bowel preparation and chromoendoscopy use are associated with improved adenoma detection, while surveillance intervals of less than 3 years are associated with a reduction of PCCRC incidence. In LS, high-quality colonoscopy surveillance is of utmost importance for CRC prevention.
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Adenoma , Neoplasias Colorretais Hereditárias sem Polipose , Neoplasias Colorretais , Adenoma/complicações , Adenoma/diagnóstico , Adenoma/epidemiologia , Colonoscopia , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/epidemiologia , Neoplasias Colorretais/prevenção & controle , Neoplasias Colorretais Hereditárias sem Polipose/complicações , Neoplasias Colorretais Hereditárias sem Polipose/diagnóstico , Detecção Precoce de Câncer , Humanos , Incidência , Fatores de RiscoRESUMO
Germline pathogenic variants in BRCA1 and BRCA2 genes (BRCA1/2) explain an important fraction of hereditary breast/ovarian cancer (HBOC) cases. Genetic testing generally involves examining coding regions and exon/intron boundaries, thus the frequency of deleterious variants in non-coding regions is unknown. Here we analysed BRCA1/2 whole cDNA in a large cohort of 320 unsolved high-risk HBOC cases in order to identify potential splicing alterations explained by variants in BRCA1/2 deep intronic regions. Whole RNA splicing profiles were analysed by RT-PCR using Sanger sequencing or high-resolution electrophoresis in a QIAxcel instrument. Known predominant BRCA1/2 alternative splicing events were detected, together with two novel events BRCA1 â¼21 and BRCA2 Δ18q_27p. BRCA2 exon 3 skipping was detected in one patient (male) affected with breast cancer, caused by a known Portuguese founder mutation (c.156_157insAluYa5). An altered BRCA2 splicing pattern was detected in three patients, consisting in the up-regulation of â¼20A, Δ22 and â¼20A+Δ22 transcripts. In silico analysis and semi-quantitative data identified the polymorphism BRCA2 c.8755-66T>C as a potential modifier of Δ22 levels. Our findings suggest that mRNA alterations in BRCA1/2 caused by deep intronic variants are rare in Spanish population. However, RNA analysis complements DNA-based strategies allowing the identification of alterations that could go undetected by conventional testing.
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Proteína BRCA1/genética , Proteína BRCA2/genética , DNA Complementar/genética , Predisposição Genética para Doença , Síndrome Hereditária de Câncer de Mama e Ovário/genética , Síndrome Hereditária de Câncer de Mama e Ovário/patologia , Mutação/genética , Adulto , Estudos de Casos e Controles , Feminino , Seguimentos , Humanos , Pessoa de Meia-Idade , Prognóstico , Splicing de RNA , Estudos RetrospectivosRESUMO
PURPOSE: To identify predictors of patient acceptance of non-in-person cancer genetic visits before and after the COVID-19 pandemic and assess the preferences of health-care professionals. METHODS: Prospective multicenter cohort study (N = 578, 1 February 2018-20 April 2019) and recontacted during the COVID-19 lockdown in April 2020. Health-care professionals participated in May 2020. Association of personality traits and clinical factors with acceptance was assessed with multivariate analysis. RESULTS: Before COVID-19, videoconference was more accepted than telephone-based visits (28% vs. 16% pretest, 30% vs. 19% post-test). Predictors for telephone visits were age (pretest, odds ratio [OR] 10-year increment = 0.79; post-test OR 10Y = 0.78); disclosure of panel testing (OR = 0.60), positive results (OR = 0.52), low conscientiousness group (OR = 2.87), and post-test level of uncertainty (OR = 0.93). Predictors for videoconference were age (pretest, OR 10Y = 0.73; post-test, OR 10Y = 0.75), educational level (pretest: OR = 1.61), low neuroticism (pretest, OR = 1.72), and post-test level of uncertainty (OR = 0.96). Patients' reported acceptance for non-in-person visits after COVID-19 increased to 92% for the pretest and 85% for the post-test. Health-care professionals only preferred non-in-person visits for disclosure of negative results (83%). CONCLUSION: These new delivery models need to recognize challenges associated with age and the psychological characteristics of the population and embrace health-care professionals' preferences.
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COVID-19 , Neoplasias , Estudos de Coortes , Controle de Doenças Transmissíveis , Predisposição Genética para Doença , Humanos , Pandemias , Estudos Prospectivos , SARS-CoV-2RESUMO
Hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC) is a very rare hereditary disorder characterized by cutaneous leiomyomas (CLMs), uterine leiomyomas (ULMs), renal cysts (RCys) and renal cell cancers (RCCs). We aimed to describe the genetics, clinical features and potential genotype-phenotype associations in the largest cohort of fumarate hydratase enzyme mutation carriers known from Spain using a multicentre, retrospective study of individuals with a genetic or clinical diagnosis of HLRCC. We collected clinical information from medical records, analysed genetic variants and looked for genotype-phenotype associations. Analyses were performed using R 3.6.0. software. We included 197 individuals: 74 index cases and 123 relatives. CLMs were diagnosed in 65% of patients, ULMs in 90% of women, RCys in 37% and RCC in 10.9%. Twenty-seven different pathogenic variants were detected, 12 (44%) of them not reported previously. Patients with missense pathogenic variants showed higher frequencies of CLMs, ULMs and RCys, than those with loss-of-function variants (p = 0.0380, p = 0.0015 and p = 0.024, respectively). This is the first report of patients with HLRCC from Spain. The frequency of RCCs was lower than those reported in the previously published series. Individuals with missense pathogenic variants had higher frequencies of CLMs, ULMs and RCys.
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Lynch syndrome (LS) is a common cause of hereditary colorectal cancer (CRC). Some CRC patients develop mismatch repair deficiency without germline pathogenic mutation, known as Lynch-like syndrome (LLS). We compared the risk of CRC in first-degree relatives (FDRs) in LLS and LS patients. LLS was diagnosed when tumors showed immunohistochemical loss of MSH2, MSH6, and PMS2; or loss of MLH1 with BRAF wild type; and/or no MLH1 methylation and absence of pathogenic mutation in these genes. CRC and other LS-related neoplasms were followed in patients diagnosed with LS and LLS and among their FDRs. Standardized incidence ratios (SIRs) were calculated for CRC and other neoplasms associated with LS among FDRs of LS and LLS patients. In total, 205 LS (1205 FDRs) and 131 LLS families (698 FDRs) had complete pedigrees. FDRs of patients with LLS had a high incidence of CRC (SIR, 2.08; 95% confidence interval (CI), 1.56-2.71), which was significantly lower than that in FDRs of patients with LS (SIR, 4.25; 95% CI, 3.67-4.90; p < 0.001). The risk of developing other neoplasms associated with LS also increased among FDR of LLS patients (SIR, 2.04; 95% CI, 1.44-2.80) but was lower than that among FDR of patients with LS (SIR, 5.01, 95% CI, 4.26-5.84; p < 0.001). FDRs with LLS have an increased risk of developing CRC as well as LS-related neoplasms, although this risk is lower than that of families with LS. Thus, their management should take into account this increased risk.
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BACKGROUND & AIMS: Lynch syndrome is characterized by DNA mismatch repair (MMR) deficiency. Some patients with suspected Lynch syndrome have DNA MMR deficiencies but no detectable mutations in genes that encode MMR proteins-this is called Lynch-like syndrome (LLS). There is no consensus on management of patients with LLS. We collected data from a large series of patients with LLS to identify clinical and pathology features. METHODS: We collected data from a nationwide-registry of patients with colorectal cancer (CRC) in Spain. We identified patients whose colorectal tumors had loss of MSH2, MSH6, PMS2, or MLH1 (based on immunohistochemistry), without the mutation encoding V600E in BRAF (detected by real-time PCR), and/or no methylation at MLH1 (determined by methylation-specific multiplex ligation-dependent probe amplification), and no pathogenic mutations in MMR genes, BRAF, or EPCAM (determined by DNA sequencing). These patients were considered to have LLS. We collected data on demographic, clinical, and pathology features and family history of neoplasms. The χ2 test was used to analyze the association between qualitative variables, followed by the Fisher exact test and the Student t test or the Mann-Whitney test for quantitative variables. RESULTS: We identified 160 patients with LLS; their mean age at diagnosis of CRC was 55 years and 66 patients were female (41%). The Amsterdam I and II criteria for Lynch syndrome were fulfilled by 11% of cases and the revised Bethesda guideline criteria by 65% of cases. Of the patients with LLS, 24% were identified in universal screening. There were no proportional differences in sex, indication for colonoscopy, immunohistochemistry, pathology findings, or personal history of CRC or other Lynch syndrome-related tumors between patients who met the Amsterdam and/or Bethesda criteria for Lynch syndrome and patients identified in universal screening for Lynch syndrome, without a family history of CRC. CONCLUSIONS: Patients with LLS have homogeneous clinical, demographic, and pathology characteristics, regardless of family history of CRC.
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Neoplasias Colorretais Hereditárias sem Polipose , Neoplasias Colorretais , Síndromes Neoplásicas Hereditárias , Neoplasias Colorretais Hereditárias sem Polipose/diagnóstico , Neoplasias Colorretais Hereditárias sem Polipose/genética , Reparo de Erro de Pareamento de DNA , Feminino , Humanos , Instabilidade de Microssatélites , Proteína 1 Homóloga a MutLRESUMO
Multigene panels provide a powerful tool for analyzing several genes simultaneously. We evaluated the frequency of pathogenic variants (PV) in customized predefined panels according to clinical suspicion by phenotype and compared it to the yield obtained in the analysis of our clinical research gene panel. We also investigated mutational yield of opportunistic testing of BRCA1/2 and mismatch repair (MMR) genes in all patients. A total of 1,205 unrelated probands with clinical suspicion of hereditary cancer were screened for germline mutations using panel testing. Overall, 1,048 females and 157 males were analyzed, mean age at cancer diagnosis was 48; 883 had hereditary breast/ovarian cancer-suspicion, 205 hereditary nonpolyposis colorectal cancer (HNPCC)-suspicion, 73 adenomatous-polyposis-suspicion and 44 with other/multiple clinical criteria. At least one PV was found in 150 probands (12%) analyzed by our customized phenotype-driven panel. Tumoral MMR deficiency predicted for the presence of germline MMR gene mutations in patients with HNPCC-suspicion (46/136 vs. 0/56 in patients with and without MMR deficiency, respectively). Opportunistic testing additionally identified five MSH6, one BRCA1 and one BRCA2 carriers (0.6%). The analysis of the extended 24-gene panel provided 25 additional PVs (2%), including in 4 out of 51 individuals harboring MMR-proficient colorectal tumors (2 CHEK2 and 2 ATM). Phenotype-based panels provide a notable rate of PVs with clinical actionability. Opportunistic testing of MMR and BRCA genes leads to a significant straightforward identification of MSH6, BRCA1 and BRCA2 mutation carriers, and endorses the model of opportunistic testing of genes with clinical utility within a standard genetic counseling framework.
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Proteína BRCA1/genética , Proteína BRCA2/genética , Predisposição Genética para Doença , Testes Genéticos/métodos , Síndromes Neoplásicas Hereditárias/diagnóstico , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Reparo de Erro de Pareamento de DNA , Feminino , Genes Supressores de Tumor , Mutação em Linhagem Germinativa , Humanos , Masculino , Anamnese , Pessoa de Meia-Idade , Síndromes Neoplásicas Hereditárias/genética , Linhagem , FenótipoRESUMO
PURPOSE: Disruption of splicing motifs by genetic variants can affect the correct generation of mature mRNA molecules leading to aberrant transcripts. In some cases, variants may alter the physiological transcription profile composed of several transcripts, and an accurate in vitro evaluation is crucial to establish their pathogenicity. In this study, we have characterized a novel PALB2 variant c.3201+5G>T identified in a breast cancer family. METHODS: Peripheral blood RNA was analyzed in two carriers and ten controls by RT-PCR and Sanger sequencing. The splicing profile was also characterized by semi-quantitative capillary electrophoresis and quantitative PCR. RAD51 foci formation and PALB2 LOH status were evaluated in primary breast tumor samples from the carriers. RESULTS: PALB2 c.3201+5G>T disrupts intron 11 donor splice site and modifies the abundance of several alternative transcripts (∆11, ∆12, and ∆11,12), also present in control samples. All transcripts are predicted to encode for non-functional proteins. Semi-quantitative and quantitative analysis of PALB2 full-length transcript indicated haploinsufficiency in carriers. One tumor exhibited PALB2 LOH and RAD51 assay indicated homologous recombination deficiency in both tumors. CONCLUSIONS: Our results support a pathogenic classification for PALB2 c.3201+5G>T, highlighting the impact of variants causing an imbalanced expression of natural RNA isoforms in cancer susceptibility.
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Processamento Alternativo , Neoplasias da Mama/genética , Proteína do Grupo de Complementação N da Anemia de Fanconi/genética , Mutação em Linhagem Germinativa , Polimorfismo de Nucleotídeo Único , Feminino , Perfilação da Expressão Gênica , Predisposição Genética para Doença , Humanos , Perda de Heterozigosidade , Pessoa de Meia-Idade , Linhagem , Análise de Sequência de RNARESUMO
BACKGROUND: Genetic analysis of BRCA1 and BRCA2 for the diagnosis of hereditary breast and ovarian cancer (HBOC) is commonly restricted to coding regions and exon-intron boundaries. Although germline pathogenic variants in these regions explain about ~20% of HBOC cases, there is still an important fraction that remains undiagnosed. We have screened BRCA1/2 deep intronic regions to identify potential spliceogenic variants that could explain part of the missing HBOC susceptibility. METHODS: We analysed BRCA1/2 deep intronic regions by targeted gene sequencing in 192 high-risk HBOC families testing negative for BRCA1/2 during conventional analysis. Rare variants (MAF <0.005) predicted to create/activate splice sites were selected for further characterisation in patient RNA. The splicing outcome was analysed by RT-PCR and Sanger sequencing, and allelic imbalance was also determined when heterozygous exonic loci were present. RESULTS: A novel transcript was detected in BRCA1 c.4185+4105C>T variant carrier. This variant promotes the inclusion of a pseudoexon in mature mRNA, generating an aberrant transcript predicted to encode for a non-functional protein. Quantitative and allele-specific assays determined haploinsufficiency in the variant carrier, supporting a pathogenic effect for this variant. Genotyping of 1030 HBOC cases and 327 controls did not identify additional carriers in Spanish population. CONCLUSION: Screening of BRCA1/2 intronic regions has identified the first BRCA1 deep intronic variant associated with HBOC by pseudoexon activation. Although the frequency of deleterious variants in these regions appears to be low, our study highlights the importance of studying non-coding regions and performing comprehensive RNA assays to complement genetic diagnosis.
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Proteína BRCA1/genética , Síndrome Hereditária de Câncer de Mama e Ovário/genética , Íntrons , Adulto , Proteína BRCA2/genética , Neoplasias da Mama Masculina/genética , Estudos de Casos e Controles , Simulação por Computador , Éxons , Feminino , Regulação da Expressão Gênica , Frequência do Gene , Testes Genéticos , Mutação em Linhagem Germinativa , Humanos , Masculino , Splicing de RNA , RNA Mensageiro/genéticaRESUMO
PURPOSE: Few and small studies have been reported about multigene testing usage by massively parallel sequencing in European cancer families. There is an open debate about what genes should be tested, and the actionability of some included genes is under research. METHODS: We investigated a panel of 34 known high/moderate-risk cancer genes, including 16 related to breast or ovarian cancer (BC/OC) genes, and 63 candidate genes to BC/OC in 192 clinically suspicious of hereditary breast/ovarian cancer (HBOC) Spanish families without pathogenic variants in BRCA1 or BRCA2 (BRCA1/2). RESULTS: We identified 16 patients who carried a high- or moderate-risk pathogenic variant in eight genes: 4 PALB2, 3 ATM, 2 RAD51D, 2 TP53, 2 APC, 1 BRIP1, 1 PTEN and 1 PMS2. These findings led to increased surveillance or prevention options in 12 patients and predictive testing in their family members. We detected 383 unique variants of uncertain significance in known cancer genes, of which 35 were prioritized in silico. Eighteen loss-of-function variants were detected in candidate BC/OC genes in 17 patients (1 BARD1, 1 ERCC3, 1 ERCC5, 2 FANCE, 1 FANCI, 2 FANCL, 1 FANCM, 1 MCPH1, 1 PPM1D, 2 RBBP8, 3 RECQL4 and 1 with SLX4 and XRCC2), three of which also carry pathogenic variants in known cancer genes. CONCLUSIONS: Eight percent of the BRCA1/2 negative patients carry pathogenic variants in other actionable genes. The multigene panel usage improves the diagnostic yield in HBOC testing and it is an effective tool to identify potentially new candidate genes.
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Biomarcadores Tumorais , Genes BRCA1 , Genes BRCA2 , Síndrome Hereditária de Câncer de Mama e Ovário/diagnóstico , Síndrome Hereditária de Câncer de Mama e Ovário/genética , Adulto , Alelos , Biologia Computacional/métodos , Feminino , Predisposição Genética para Doença , Testes Genéticos , Variação Genética , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Análise de Sequência de DNA , Espanha , Adulto JovemRESUMO
In silico tools for splicing defect prediction have a key role to assess the impact of variants of uncertain significance. Our aim was to evaluate the performance of a set of commonly used splicing in silico tools comparing the predictions against RNA in vitro results. This was done for natural splice sites of clinically relevant genes in hereditary breast/ovarian cancer (HBOC) and Lynch syndrome. A study divided into two stages was used to evaluate SSF-like, MaxEntScan, NNSplice, HSF, SPANR, and dbscSNV tools. A discovery dataset of 99 variants with unequivocal results of RNA in vitro studies, located in the 10 exonic and 20 intronic nucleotides adjacent to exon-intron boundaries of BRCA1, BRCA2, MLH1, MSH2, MSH6, PMS2, ATM, BRIP1, CDH1, PALB2, PTEN, RAD51D, STK11, and TP53, was collected from four Spanish cancer genetic laboratories. The best stand-alone predictors or combinations were validated with a set of 346 variants in the same genes with clear splicing outcomes reported in the literature. Sensitivity, specificity, accuracy, negative predictive value (NPV) and Mathews Coefficient Correlation (MCC) scores were used to measure the performance. The discovery stage showed that HSF and SSF-like were the most accurate for variants at the donor and acceptor region, respectively. The further combination analysis revealed that HSF, HSF+SSF-like or HSF+SSF-like+MES achieved a high performance for predicting the disruption of donor sites, and SSF-like or a sequential combination of MES and SSF-like for predicting disruption of acceptor sites. The performance confirmation of these last results with the validation dataset, indicated that the highest sensitivity, accuracy, and NPV (99.44%, 99.44%, and 96.88, respectively) were attained with HSF+SSF-like or HSF+SSF-like+MES for donor sites and SSF-like (92.63%, 92.65%, and 84.44, respectively) for acceptor sites. We provide recommendations for combining algorithms to conduct in silico splicing analysis that achieved a high performance. The high NPV obtained allows to select the variants in which the study by in vitro RNA analysis is mandatory against those with a negligible probability of being spliceogenic. Our study also shows that the performance of each specific predictor varies depending on whether the natural splicing sites are donors or acceptors.