Supp Tables S1-S6 (including variant classification, bioinformatics predictions versus experimental data, primer sequences, summary of biological, clinical, tumoral, familial and multifactorial data, and description of statistical analysis approaches)

Supplementary Tables S1-S4. Table S1. Description of primers used in this study. Table S2. Variants selected in BRCA2 exon 12 and its flanking intronic regions. Table S3. Overview of bioinformatics predictions and experimental data obtained for the 40 selected BRCA2 exon 12 variants. Table S4. Clinical and family data of patients carrying BRCA2 exon 12 spliceogenic variants.

Fig. S1 to S10. Figure S1. Variant selection from human variation databases; Figure S2. Capillary electrophoresis analyses of BRCA2 exon 12 splicing patterns in minigene assays of presumed LoF variants; Figure S3. Bioinformatics predictions of 3'/5' ss alterations for variants located at position IVS{plus minus}1/2 of BRCA2 exon 12; Figure S4. Bioinformatics analysis of variants predicted to alter 3'/5' ss of BRCA2 exon 12 (â^†MES {less than or equal to} -15%); Figure S5. Capillary electrophoresis analyses of BRCA2 exon 12 splicing patterns in minigene assays of variants predicted to alter 3'/5' ss (A) or ESR (B); Figure S6. Capillary electrophoresis analyses of BRCA2 exon 12 splicing patterns in control and patient lymphoblastoid cell lines; Figure S7. RT-PCR analysis of BRCA2 exon 12 splicing patterns in puromycin- or mock-treated lymphoblastoid cell lines of control individuals and patients carrying the c.6844G>T or c.6901G>T nonsense variants; Figure S8. Capillary electrophoresis analyses of BRCA2 exon 12 splicing patterns in variant-expressing mESC; Figure S9. Quantitation of BRCA2 protein expression in mESC; Figure S10. Sensitivity of BRCA2 variants to cisplatin and PARP inhibitors.

Supp Table of contents, Supp Materials and Methods, Supp Figures S1-S17 (including description of BRCA2 mRNA and protein domains, selection of BRCA2 variants, minigene structure, RNA splicing data versus bioinformatics predictions, minigene results versus patients' RNA and mESC's data, and results from mESC complementation assays), Supp Note and Supp Reference

Background: Large genomic rearrangements (LGR) in BRCA1 consisting of deletions/duplications of one or several exons have been found throughout the gene with a large proportion occurring in the 5′ region from the promoter to exon 2. The aim of this study was to better characterize those LGR in French high-risk breast/ovarian cancer families. Methods: DNA from 20 families with one apparent duplication and nine deletions was analyzed with a dedicated comparative genomic hybridization (CGH) array, high-resolution BRCA1 Genomic Morse Codes analysis and Sanger sequencing. Results: The apparent duplication was in fact a tandem triplication of exons 1 and 2 and part of intron 2 of BRCA1, fully characterized here for the first time. We calculated a causality score with the multifactorial model from data obtained from six families, classifying this variant as benign. Among the nine deletions detected in this region, eight have never been identified. The breakpoints fell in six recurrent regions and could confirm some specific conformation of the chromatin. Conclusions: Taken together, our results firmly establish that the BRCA1 5′ region is a frequent site of different LGRs and highlight the importance of the segmental duplication and Alu sequences, particularly the very high homologous region, in the mechanism of a recombination event. This also confirmed that those events are not systematically deleterious.

INTRODUCTION:Apoptosis deregulation have been associated to tumorigenesis process and was highlighted as a prominent hallmark of cancer. Several mutations have been reported in several forms of Blood cancer. However, it has never been investigated in familial aggregations of hematological malignancies.METHODS:In this study, we performed a mutational analysis by sequencing the entire coding regions in four key apoptotic genes FAS, FASLG, CASP8 and CASP10 in 92 independent families belonging to French and Tunisian populations and diagnosed with several forms of familial hematological malignancies.RESULTS:We report 15 genetic variations among which 7 were previously reported in several form of cancers and have a potential effect on gene expression. Particularly, the CASP8 variants p.Asp302His and p.Lys337Lys were detected in 15% and 10% of our group of patients respectively and were previously reported in association to breast cancer and to breast cancer susceptibility.DISCUSSION:In this study, we do not report the underlining deleterious mutations in familial hematological malignancies, but we describe some variants with potential risk of developing blood cancer. To gain further insights on the association between apoptosis pathway deregulation and familial hematological malignancies, more apoptotic genes should be investigated.

Up to 80% of BRCA1 and BRCA2 genetic variants remain of uncertain clinical significance (VUSs). Only variants classified as pathogenic or likely pathogenic can guide breast and ovarian cancer prevention measures and treatment by PARP inhibitors. We report the first results of the ongoing French national COVAR (cosegregation variant) study, the aim of which is to classify BRCA1/2 VUSs. The classification method was a multifactorial model combining different associations between VUSs and cancer, including cosegregation data. At this time, among the 653 variants selected, 101 (15%) distinct variants shared by 1,624 families were classified as pathogenic/likely pathogenic or benign/likely benign by the COVAR study. Sixty-six of the 101 (65%) variants classified by COVAR would have remained VUSs without cosegregation data. Of note, among the 34 variants classified as pathogenic by COVAR, 16 remained VUSs or likely pathogenic when following the ACMG/AMP variant classification guidelines. Although the initiation and organization of cosegregation analyses require a considerable effort, the growing number of available genetic tests results in an increasing number of families sharing a particular variant, and thereby increases the power of such analyses. Here we demonstrate that variant cosegregation analyses are a powerful tool for the classification of variants in the BRCA1/2 breast-ovarian cancer predisposition genes.

Background Mutations of the BRCA2 gene are the most frequent alterations found in germline DNA from men with prostate cancer (PrCa), but clinical parameters that could better orientate for BRCA2 mutation screening need to be established. Methods Germline DNA from 325 PrCa patients (median age at diagnosis: 57 years old) was screened for BRCA2 mutation. The mutation frequency was compared between three subgroups: patients with an age at diagnosis at 55 years old and under (Group I); a personal or family history of breast, uterine or ovarian cancer (Group II); or a metastatic disease (Group III). Frequency of BRCA2 mutations was established for each combination of phenotypes, and compared between patients meeting or not the criteria for each subgroup using Fisher's exact test. Mutual information, direct effect, elasticity and contribution to the mutational status of each phenotype, taking into account overlap between subgroups, were also estimated using Bayesian algorithms. Results The proportion of BRCA2 mutation was 5.9% in Group I, 10.9% in Group II and 6.9% in Group III. The frequency of BRCA2 mutation was significantly higher among patients of Group II (p = .006), and reached 15.6% among patients of this group who presented a metastatic disease. Mutual information, direct effect, elasticity and contribution to the mutational status were the highest for phenotype II. Fifteen (71.4%) of the 21 BRCA2 mutation carriers had an aggressive form of the disease. Four (19%) of them died from PrCa after a median follow-up duration of 64.5 months. Conclusions Our results showed that a higher frequency of BRCA2 mutation carriers is observed, not only among PrCa patients with young onset or a metastatic disease, but also with a personal or a familial history of breast cancer.

AbstractGermline nonsense and canonical splice site variants identified in disease-causing genes are generally considered as loss-of-function (LoF) alleles and classified as pathogenic. However, a fraction of such variants could maintain function through their impact on RNA splicing. To test this hypothesis, we used the alternatively spliced BRCA2 exon 12 (E12) as a model system because its in-frame skipping leads to a potentially functional protein. All E12 variants corresponding to putative LoF variants or predicted to alter splicing (n = 40) were selected from human variation databases and characterized for their impact on splicing in minigene assays and, when available, in patient lymphoblastoid cell lines. Moreover, a selection of variants was analyzed in a mouse embryonic stem cell–based functional assay. Using these complementary approaches, we demonstrate that a subset of variants, including nonsense variants, induced in-frame E12 skipping through the modification of splice sites or regulatory elements and, consequently, led to an internally deleted but partially functional protein. These data provide evidence, for the first time in a cancer-predisposition gene, that certain presumed null variants can retain function due to their impact on splicing. Further studies are required to estimate cancer risk associated with these hypomorphic variants. More generally, our findings highlight the need to exercise caution in the interpretation of putative LoF variants susceptible to induce in-frame splicing modifications.Significance:This study presents evidence that certain presumed loss-of-function variants in a cancer predisposition gene can retain function due to their direct impact on RNA splicing.

Variant interpretation is the key issue in molecular diagnosis. Spliceogenic variants exemplify this issue as each nucleotide variant can be deleterious via disruption or creation of splice site consensus sequences. Consequently, reliable in silico prediction of variant spliceogenicity would be a major improvement. Thanks to an international effort, a set of 395 variants studied at the mRNA level and occurring in 5' and 3' consensus regions (defined as the 11 and 14 bases surrounding the exon/intron junction, respectively) was collected for 11 different genes, including BRCA1, BRCA2, CFTR and RHD, and used to train and validate a new prediction protocol named Splicing Prediction in Consensus Elements (SPiCE). SPiCE combines in silico predictions from SpliceSiteFinder-like and MaxEntScan and uses logistic regression to define optimal decision thresholds. It revealed an unprecedented sensitivity and specificity of 99.5 and 95.2%, respectively, and the impact on splicing was correctly predicted for 98.8% of variants. We therefore propose SPiCE as the new tool for predicting variant spliceogenicity. It could be easily implemented in any diagnostic laboratory as a routine decision making tool to help geneticists to face the deluge of variants in the next-generation sequencing era. SPiCE is accessible at (https://sourceforge.net/projects/spicev2-1/).

Germline mutations of the BRCA2 gene were reported in men with prostate cancer (PrCa), but clinical criteria for BRCA2 screening need to be clarified. Prostate cancer patients included in this study were selected among the ones who were recruited in the PROGENE study. This study has been approved by the CCP Ile de France IV (IRB: 00003835). All patients have provided written informed consent in order to participate in the study. Germline DNA from 325 PrCa patients (median age at diagnosis: 57 years old) was screened for BRCA2 mutation. The mutation frequency was compared between three groups: patients with an age at diagnosis at 55 years old and under (Group I); a personal or family history of breast (BrCa), uterine (UtCa) or ovarian cancer (OvCa) (Group II); or a metastatic disease (Group III). The proportion of BRCA2 mutation was 5.9% in Group I, 10.9% in Group II and 6.9% in Group III (Table). The frequency of BRCA2 mutation was significantly higher among patients of Group II (P=0.006), and reached 15.6% among patients of this group who presented a metastatic disease. Mutual information analysis showed that contribution towards the predicted mean of the positive mutational status, according the direct effect of phenotype observed in each group, was 16%, 63% and 22% for group I, II and III, respectively. The frequency of BRCA2 mutation didn’t differ according to ethnicity or prostate cancer familial status. The median age at diagnosis of the 21 BRCA2 mutation carriers was 57 years old (range: 43-74). Fifteen (71.4%) of the 21 BRCA2 mutation carriers had an aggressive form of the disease. Four (19%) of them died from PrCa after a median follow-up duration of 64.5 months.Table:Frequency of BRCA2 mutationsCriteria of selectionNumber of patientsNumber of patients with BRCA2 mutationBRCA2 mutation frequency (%)None325216.5Age at diagnosis ≤ 55 years (Group I)15295.9Personal or familial history of Br/Ut/OvCa (Group II)1371510.9Metastatic PrCa (Group III)13096.9Age at diagnosis ≤ 55 years & Personal or familial history of Br/Ut/OvCa (Groups I & II)38513.2Personal or familial history of Br/Ut/OvCa & Metastatic PrCa (Groups II & III)32515.6Age at diagnosis ≤ 55 years & Metastatic PrCa (Groups I & III)3239.4Age at diagnosis ≤ 55 years & Personal or familial history of Br/Ut/OvCa & Metastatic PrCa (Groups II & II & III)8112.5 Open table in a new tab Our results showed that a higher frequency of BRCA2 mutation carriers is observed, not only among PrCa patients with young onset or a metastatic disease, but also with a personal or a familial history of breast cancer.

Abstract BRCA2 is a clinically actionable gene implicated in breast and ovarian cancer predisposition that has become a high priority target for improving the classification of variants of unknown significance (VUS). Among all BRCA2 VUS, those causing partial/leaky splicing defects are the most challenging to classify because the minimal level of full-length (FL) transcripts required for normal function remains to be established. Here, we explored BRCA2 exon 3 (BRCA2e3) as a model for calibrating variant-induced spliceogenicity and estimating thresholds for BRCA2 haploinsufficiency. In silico predictions, minigene splicing assays, patients' RNA analyses, a mouse embryonic stem cell (mESC) complementation assay and retrieval of patient-related information were combined to determine the minimal requirement of FL BRCA2 transcripts. Of 100 BRCA2e3 variants tested in the minigene assay, 64 were found to be spliceogenic, causing mild to severe RNA defects. Splicing defects were also confirmed in patients' RNA when available. Analysis of a neutral leaky variant (c.231T>G) showed that a reduction of approximately 60% of FL BRCA2 transcripts from a mutant allele does not cause any increase in cancer risk. Moreover, data obtained from mESCs suggest that variants causing a decline in FL BRCA2 with approximately 30% of wild-type are not pathogenic, given that mESCs are fully viable and resistant to DNA-damaging agents in those conditions. In contrast, mESCs producing lower relative amounts of FL BRCA2 exhibited either null or hypomorphic phenotypes. Overall, our findings are likely to have broader implications on the interpretation of BRCA2 variants affecting the splicing pattern of other essential exons. Significance: These findings demonstrate that BRCA2 tumor suppressor function tolerates substantial reduction in full-length transcripts, helping to determine the pathogenicity of BRCA2 leaky splicing variants, some of which may not increase cancer risk.

Abstract BRCA1 mutations have been identified that increase the risk of developing hereditary breast and ovarian cancers. Genetic screening is now offered to patients with a family history of cancer, to adapt their treatment and the management of their relatives. However, a large number of BRCA1 variants of uncertain significance (VUS) are detected. To better understand the significance of these variants, a high-throughput structural and functional analysis was performed on a large set of BRCA1 VUS. Information on both cellular localization and homology-directed DNA repair (HR) capacity was obtained for 78 BRCT missense variants in the UMD-BRCA1 database and measurement of the structural stability and phosphopeptide-binding capacities was performed for 42 mutated BRCT domains. This extensive and systematic analysis revealed that most characterized causal variants affect BRCT-domain solubility in bacteria and all impair BRCA1 HR activity in cells. Furthermore, binding to a set of 5 different phosphopeptides was tested: all causal variants showed phosphopeptide-binding defects and no neutral variant showed such defects. A classification is presented on the basis of mutated BRCT domain solubility, phosphopeptide-binding properties, and VUS HR capacity. These data suggest that HR-defective variants, which present, in addition, BRCT domains either insoluble in bacteria or defective for phosphopeptide binding, lead to an increased cancer risk. Furthermore, the data suggest that variants with a WT HR activity and whose BRCT domains bind with a WT affinity to the 5 phosphopeptides are neutral. The case of variants with WT HR activity and defective phosphopeptide binding should be further characterized, as this last functional defect might be sufficient per se to lead to tumorigenesis. Implications: The analysis of the current study on BRCA1 structural and functional defects on cancer risk and classification presented may improve clinical interpretation and therapeutic selection.

Mutations are responsible for familial cancer syndromes which account for approximately 5–10 % of all types of cancers. Familial cancers are often caused by genetic alterations occurring either in tumor suppressor or genomic stability genes such as TP53. In this study, we have analyzed the TP53 gene by direct sequencing approach, in a panel of 18 Tunisian familial hematological malignancies cases including several forms of leukemia, lymphoma and myeloid syndrome and 22 cases of sporadic acute leukemia. In one familial case diagnosed with acute lymphoblastic leukemia, we reported an intronic substitution 559+1 G>A which may disrupt the splice site and impact the normal protein function. Most of the deleterious mutations (Arg158His; Pro282Trp; Thr312Ser) as classified by IARC data base, were commonly reported in ALL cases studied here. The cosegregation of the two variants rs1042522 and rs1642785 was observed in most patients which may be in favor of the presence of linkage disequilibrium. The most defined TP53 mutations found here were identified in acute lymphoblastic leukemia context whereas only 3 % of mutations have been in previous studies. The cosegregation of the two recurrent variant rs1042522 and rs1642785 should be further confirmed.

The genetic predisposition to familial hematological malignancies has been previously reported highlighting inherited gene mutations. Several genes have been reported but genetic basis remains not well defined. In this study, we extended our investigation to a potential candidate GATA2 gene which was analyzed by direct sequencing in 119 cases including familial aggregations with a variety of hematological malignancies and sporadic acute leukemia belonging to Tunisian and French populations. We reported a deleterious p.Arg396Gln GATA2 mutation in one patient diagnosed with both sporadic acute myeloid leukemia (AML) and breast cancer. We also reported several GATA2 variations in familial cases. The absence of deleterious mutations in this large cohort of familial aggregations of hematological malignancies may strengthen the hypothesis that GATA2 mutations are an important predisposing factor, although as a secondary genetic event, required for the development of overt malignant disease.

Familial aggregation of hematological malignancies has been reported highlighting inherited genetic predisposition. In this study, we targeted four candidate genes: JAK2 and RUNX1 genes assuring a prominent function in hematological process and CBL and NPM1 as proto-oncogenes. Their disruption was described in several sporadic hematological malignancies. The aim of this study is to determine whether JAK2, CBL, RUNX1, and NPM1 germline genes mutations are involved in familial hematological malignancies. Using direct sequencing, we analyzed JAK2 (exons 12 and 14); CBL (exons 7, 8 and 9); NPM1 (exon 12) and the entire RUNX1 in 88 independent families belonging to Tunisian and French populations. Twenty-one sporadic acute leukemias were included in this study. We reported a heterozygous intronic c.1641 + 6 T > C JAK2 variant (rs182123615) found in two independent familial cases diagnosed with gastric lymphoma and Hodgkin lymphoma. The in silico analysis suggested a potential impact on splicing, but the functional splicing minigene reporter assay on rs182123615 variant showed no aberrant transcripts. In one sporadic acute myeloblastic leukemia, we reported an insertion 846 in. TGTT in exon 12 of NPM1 gene that may impact the normal reading frame. The rs182123615 JAK2 variant was described in several contexts including myeloproliferative neoplasms and congenital erythrocytosis and was supposed to be pathogenic. Through this current study, we established the assessment of pathogenicity of rs182123615 and we classified it rather as rare polymorphism.

Isocitrate dehydrogenase IDH 1 and IDH 2 mutations were reported in several cancer forms, especially in hematological malignancies, but were never been investigated in familial aggregation. The aim of this study is to determine whether germline isocitrate dehydrogenase genes mutations are involved.We targeted IDH1 and IDH2 genes in 104 familial cases belonging to Tunisian and French populations, including several forms of hematological malignancies and cosegregated solid tumors.We report one IDH1 variant: c.315 G > T, p.Gly105Gly in 15 % of cases, which was assigned to the worst outcome in several studies. Three IDH2 variants were found, among them, one intronic substitution c.543+45 G > A (rs142033117) and two new variants not previously described: c.389 A > T, p.Lys130Met and c.414 T > C, p.Thr138Thr. The p.Lys130Met was found in one case diagnosed with Waldenstrom's disease with familial history of cancer. The enrolled in silico analysis, the functional study, and the absence of this variant in control population strengthen the hypothesis of its deleterious effect.From an extended number of candidate genes analyzed in familial hematological malignancies, IDH2 might be considerably involved since we reported a potential damaging effect.

Introduction > Genetic predisposition to familial hematological malignancies was previously described through several epidemiological analyses, but the genetic basis remains unclear. The tumor-suppressor ARLTS1 gene was previously described in sporadic hematological malignancies and familial cancer context.Methods > In this study, we sequence the ARLTS1 gene in 100 patients belonging to 88 independent Tunisian and French families.Results > After gene sequencing, we report 8 genetic variations, most of which were previously reported in several cancer forms. The most common variants were W149X and C148R and were previously associated to B-cell chronic lymphocytic leukemia and to high-risk of familial breast cancer.Conclusions > These results emphasize the fact that ARLTS1 gene mutations can be considered as a potential predisposing factor in familial hematological malignancies and other several cancer forms.