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Càrrega feta de Scopus d'articles UAB 2019 (Gold, hybrid o Bronze) procedents de l'Observatori d'Accés Obert (càrrega maig 2020). Compte! Cal comprovar la versió permesa per l'editor en els bronze. This work was supported by grants BIO2012?40133 and SAF2016?80255-R from the Spanish Ministry of Economy and Competitivity (MINECO) and Pirepred (EFA086/15) from the Interreg program POCTEFA, supported by the European Regional Development Fund (ERDF) to X. dC.; FIS PI12/02585 and PI15/00355 to O. D.; PI13/01711 and PI16/01218 to S. G-E. from the Spanish Instituto de Salud Carlos III (ISCIII) funding, an initiative of the Spanish Ministry of Economy and Innovation partially supported by European Regional Development FEDER Funds. S. B. and S. G-E. are supported by the Asociaci?n Espa?ola contra el C?ncer [AECC] and the Miguel Servet Progam [CP16/00034], respectively. The CAGI experiment coordination is supported by NIH U41 HG007346 and the CAGI conference by NIH R13 HG006650. BRCA1 and BRCA2 (BRCA1/2) germline variants disrupting the DNA protective role of these genes increase the risk of hereditary breast and ovarian cancers. Correct identification of these variants then becomes clinically relevant, because it may increase the survival rates of the carriers. Unfortunately, we are still unable to systematically predict the impact of BRCA1/2 variants. In this article, we present a family of in silico predictors that address this problem, using a gene-specific approach. For each protein, we have developed two tools, aimed at predicting the impact of a variant at two different levels: Functional and clinical. Testing their performance in different datasets shows that specific information compensates the small number of predictive features and the reduced training sets employed to develop our models. When applied to the variants of the BRCA1/2 (ENIGMA) challenge in the fifth Critical Assessment of Genome Interpretation (CAGI 5) we find that these methods, particularly those predicting the functional impact of variants, have a good performance, identifying the large compositional bias towards neutral variants in the CAGI sample. This performance is further improved when incorporating to our prediction protocol estimates of the impact on splicing of the target variant.

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 ▼21 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 ▼20A, Δ22 and ▼20A+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.

BackgroundGenetic 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.MethodsWe 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 ResultsA 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.ConclusionScreening 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.

Altres ajuts: European Research Area-NET, Transcan-2 (AC15/00063), Asociación Española Contra el Cáncer (LABAE16020PORTT) i AIOC15152806CRUZ, Generalitat de Catalunya(PERIS, SLT002/16/00477 En el cas dels drets, per a usos comercials contactar amb: journals.permissions@oup.com BRCA1 and BRCA2 (BRCA1/2) -deficient tumors display impaired homologous recombination repair (HRR) and enhanced sensitivity to DNA damaging agents or to poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi). Their efficacy in germline BRCA1/2 (gBRCA1/2)-mutated metastatic breast cancers has been recently confirmed in clinical trials. Numerous mechanisms of PARPi resistance have been described, whose clinical relevance in gBRCA-mutated breast cancer is unknown. This highlights the need to identify functional biomarkers to better predict PARPi sensitivity. We investigated the in vivo mechanisms of PARPi resistance in gBRCA1 patient-derived tumor xenografts (PDXs) exhibiting differential response to PARPi. Analysis included exome sequencing and immunostaining of DNA damage response proteins to functionally evaluate HRR. Findings were validated in a retrospective sample set from gBRCA1/2-cancer patients treated with PARPi. RAD51 nuclear foci, a surrogate marker of HRR functionality, were the only common feature in PDX and patient samples with primary or acquired PARPi resistance. Consistently, low RAD51 was associated with objective response to PARPi. Evaluation of the RAD51 biomarker in untreated tumors was feasible due to endogenous DNA damage. In PARPi-resistant gBRCA1 PDXs, genetic analysis found no in-frame secondary mutations, but BRCA1 hypomorphic proteins in 60% of the models, TP53BP1 -loss in 20% and RAD51 -amplification in one sample, none mutually exclusive. Conversely, one of three PARPi-resistant gBRCA2 tumors displayed BRCA2 restoration by exome sequencing. In PDXs, PARPi resistance could be reverted upon combination of a PARPi with an ataxia-telangiectasia mutated (ATM) inhibitor. Detection of RAD51 foci in gBRCA tumors correlates with PARPi resistance regardless of the underlying mechanism restoring HRR function. This is a promising biomarker to be used in the clinic to better select patients for PARPi therapy. Our study also supports the clinical development of PARPi combinations such as those with ATM inhibitors.

BACKGROUND: BRCA1 and BRCA2 are the two principal tumour suppressor genes associated with inherited high risk of breast and ovarian cancer. Genetic testing of BRCA1/2 will often reveal one or more sequence variants of uncertain clinical significance, some of which may affect normal splicing patterns and thereby disrupt gene function. mRNA analyses are therefore among the tests used to interpret the clinical significance of some genetic variants. However, these could be confounded by the appearance of naturally occurring alternative transcripts unrelated to germline sequence variation or defects in gene function. To understand which novel splicing events are associated with splicing mutations and which are part of the normal BRCA2 splicing repertoire, a study was undertaken by members of the Evidence-based Network for the Interpretation of Germline Mutant Alleles (ENIGMA) consortium to characterise the spectrum of naturally occurring BRCA2 mRNA alternate-splicing events.METHODS: mRNA was prepared from several blood and breast tissue-derived cells and cell lines by contributing ENIGMA laboratories. cDNA representing BRCA2 alternate splice sites was amplified and visualised using capillary or agarose gel electrophoresis, followed by sequencing.RESULTS: We demonstrate the existence of 24 different BRCA2 mRNA alternate-splicing events in lymphoblastoid cell lines and both breast cancer and non-cancerous breast cell lines.CONCLUSIONS: These naturally occurring alternate-splicing events contribute to the array of cDNA fragments that may be seen in assays for mutation-associated splicing defects. Caution must be observed in assigning alternate-splicing events to potential splicing mutations.

The multifactorial likelihood analysis method has demonstrated utility for quantitative assessment of variant pathogenicity for multiple cancer syndrome genes. Independent data types currently incorporated in the model for assessing BRCA1 and BRCA2 variants include clinically calibrated prior probability of pathogenicity based on variant location and bioinformatic prediction of variant effect, co-segregation, family cancer history profile, co-occurrence with a pathogenic variant in the same gene, breast tumor pathology, and case-control information. Research and clinical data for multifactorial likelihood analysis were collated for 1,395 BRCA1/2 predominantly intronic and missense variants, enabling classification based on posterior probability of pathogenicity for 734 variants: 447 variants were classified as (likely) benign, and 94 as (likely) pathogenic; and 248 classifications were new or considerably altered relative to ClinVar submissions. Classifications were compared with information not yet included in the likelihood model, and evidence strengths aligned to those recommended for ACMG/AMP classification codes. Altered mRNA splicing or function relative to known nonpathogenic variant controls were moderately to strongly predictive of variant pathogenicity. Variant absence in population datasets provided supporting evidence for variant pathogenicity. These findings have direct relevance for BRCA1 and BRCA2 variant evaluation, and justify the need for gene-specific calibration of evidence types used for variant classification., Ohio State University Comprehensive Cancer Center Barretos Cancer Hospital. Grant Number: FINEP ‐ CT‐INFRA (02/2010) Breast Cancer Foundation of New Zealand Canadian Institutes of Health Research. Grant Number: PSR‐SIIRI‐701 Cancer Research UK. Grant Numbers: C8197/A16565, C5047/A8384, C1281/A12014, C12292/A11174, C1287/A10710, C1287/A10118, C1287/A16563, C5047/A10692, C5047/A15007 Department of Defence, USA. Grant Number: W81XWH‐10‐1‐0341 Helsinki University Hospital Research fund Scientific Foundation Asociación Española Contra el Cáncer Leiden University Medical Centre. Grant Number: Grant 30.925 Generalitat de Catalunya. Grant Numbers: PERIS_MedPerCan, URDCat, 2017SGR1282, 2017SGR496 Royal Society of New Zealand Cancer Council Victoria Netherlands Organization for Scientific Research (NWO). Grant Number: Grant 017.008.022 Breast Cancer Research Foundation Cancer Foundation of Western Australia EU H2020. Grant Number: 634935 Fundación Mutua Madrileña Seventh Framework Programme. Grant Numbers: 634935, 223175, 633784 Cancer Council South Australia Government of Galicia. Grant Number: Consolidation and structuring program: IN607B Cancer Council Tasmania Italian Association of Cancer Research. Grant Number: 15547 Queensland Cancer Fund AstraZeneca National Institute of Health (USA). Grant Numbers: 1U19 CA148065‐01, CA128978, CA192393, 1U19 CA148537, P50 CA1162091, CA116167, 1U19 CA148112 Newcastle University Dutch Cancer Society KWF. Grant Numbers: KWF/Pink Ribbon‐11704, UL2012‐5649 National Institute for Health Research. Grant Number: Manchester Biomedical Research centre (IS‐BRC‐1215 National Council of Technological and Scientific Development (CNPq) Instituto de Salud Carlos III. Grant Numbers: FIS PI15/00355, FIS PI13/01711, CIBERONC, FIS PI16/01218, PI16/00563 French National Institute of Cancer National Breast Cancer Foundation National Health and Medical Research Council. Grant Numbers: ID1061778, ID1104808 Carlos III National Health Centro de Investigación Biomédica en Red de Enferemdades Raras. Grant Number: ACCI 2016: ER17P1AC7112/2018 Cancer Council NSW Deutsche Krebshilfe. Grant Numbers: (#110837, #70111850 Fondazione Pisa. Grant Number: Grant “Clinical characterization of BRCA 1/2 Mis

While biallelic mutations in the PALB2 tumor suppressor cause Fanconi anemia subtype FA-N, monoallelic mutations predispose to breast and familial pancreatic cancer. Although hundreds of missense variants in PALB2 have been identified in patients to date, only a few have clear functional and clinical relevance. Herein, we investigate the effects of 44 PALB2 variants of uncertain significance found in breast cancer patients and provide detailed analysis by systematic functional assays. Our comprehensive functional analysis reveals two hotspots for potentially deleterious variations within PALB2, one at each terminus. PALB2 N-terminus variants p.P8L [c.23C>T], p.Y28C [c.83A>G], and p.R37H [c.110G>A] compromised PALB2-mediated homologous recombination. At the C-terminus, PALB2 variants p.L947F [c.2841G>T], p.L947S [c.2840T>C], and most strikingly p.T1030I [c.3089C>T] and p.W1140G [c.3418T>C], stood out with pronounced PARP inhibitor sensitivity and cytoplasmic accumulation in addition to marked defects in recruitment to DNA damage sites, interaction with BRCA2 and homologous recombination. Altogether, our findings show that a combination of functional assays is necessary to assess the impact of germline missense variants on PALB2 function, in order to guide proper classification of their deleteriousness.

Genetic analysis ofWe analysedA novel transcript was detected inScreening of

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. 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). 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. 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.

RAD51D mutations have been recently identified in breast (BC) and ovarian cancer (OC) families. Although an etiological role in OC appears to be present, the association of RAD51D mutations and BC risk is more unclear. We aimed to determine the prevalence of germline RAD51D mutations in Spanish BC/OC families negative for BRCA1/BRCA2 mutations. We analyzed 842 index patients: 491 from BC/OC families, 171 BC families, 51 OC families and 129 patients without family history but with early-onset BC or OC or metachronous BC and OC. Mutation detection was performed with high-resolution melting, denaturing high-performance liquid chromatography or Sanger sequencing. Three mutations were found in four families with BC and OC cases (0.82%). Two were novel: c.1A>T (p.Met1?) and c.667+2_667+23del, leading to the exon 7 skipping and one previously described: c.674C>T (p.Arg232*). All were present in BC/OC families with only one OC. The c.667+2_667+23del cosegregated in the family with one early-onset BC and two bilateral BC cases. We also identified the c.629C>T (p.Ala210Val) variant, which was predicted in silico to be potentially pathogenic. About 1% of the BC and OC Spanish families negative for BRCA1/BRCA2 are carriers of RAD51D mutations. The presence of several BC mutation carriers, albeit in the context of familial OC, suggests an increased risk for BC, which should be taken into account in the follow-up and early detection measures. RAD51D testing should be considered in clinical setting for families with BC and OC, irrespective of the number of OC cases in the family.

This abstract was withdrawn by the authors.

Classification of intronic and predicted missense changes in the breast cancer susceptibility genes BRCA1 and BRCA2 remains a significant challenge for management of patients carrying these variants. Defective mRNA splicing is established as a pathway to disease, and mRNA analysis of unclassified variants has been shown to assist in classification and genetic counselling. However the interpretation of splicing assay results can be difficult, particularly for those variants that give rise to aberrations in a background of naturally occurring isoforms. The ENIGMA (Evidence-based Network for the Interpretation of Germline Mutant Alleles) consortium was set up to facilitate research and improve research methods used to classify rare variants in the BRCA1 and BRCA2 (and potentially other) breast cancer predisposition genes. ENIGMA has established a Splicing Working Group, with stated purpose to pool the expertise of different active research groups to conduct large-scale studies that improve the clinical classification of likely spliceogenic variants. An initial project of the Splicing Working Group is to assess the consistency of protocols and results obtained across the multiple participating laboratories from Australia, Europe, UK and the USA. A comparison of mRNA assay protocols in use across 21 labs has identified differences in source material for RNA assays (cultured and uncultured lymphocytes, lymphoblastoid cell lines (LCLs) or constructs), differential use of nonsense-mediated decay inhibitors, and numerous differences in mRNA extraction, DNase treatment and cDNA synthesis methods. A second phase of the project is now underway to determine the impact of the splicing assay methods routinely used by these laboratories on assay data and clinical interpretation of a panel of variants. LCLs were selected from the kConFab repository from carriers of a variant associated with single major aberrant mRNA transcript absent in controls (n=4); carriers of a variant associated with a complicated aberrant mRNA splicing profile involving multiple transcripts including naturally occurring isoforms (n=5); female cancer-free controls (n=11). LCLs have already been distributed to 15 of 20 participating sites, and mRNA assays are underway. Preliminary results indicate that major aberrations associated with several variants mirror results previously observed for mRNA from uncultured lymphocytes. In addition, there is evidence for notable differences in expression of some isoforms compared to results previously observed for RNA from uncultured lymphocytes . This collaborative effort will provide information to inform optimal standardised mRNA splicing assay methodology, and to improve guidelines for clinical interpretation of assay results.

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.