Search

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., (© 2019 Wiley Periodicals, Inc.)

Testing for variation in BRCA1 and BRCA2 (commonly referred to as BRCA1/2), has emerged as a standard clinical practice and is helping countless women better understand and manage their heritable risk of breast and ovarian cancer. Yet the increased rate of BRCA1/2 testing has led to an increasing number of Variants of Uncertain Significance (VUS), and the rate of VUS discovery currently outpaces the rate of clinical variant interpretation. Computational prediction is a key component of the variant interpretation pipeline. In the CAGI5 ENIGMA Challenge, six prediction teams submitted predictions on 326 newly-interpreted variants from the ENIGMA Consortium. By evaluating these predictions against the new interpretations, we have gained a number of insights on the state of the art of variant prediction and specific steps to further advance this state of the art., (© 2019 Wiley Periodicals, Inc.)

Rare sequence variants in "high-risk" disease genes, often referred as unclassified variants (UVs), pose a serious challenge to genetic testing. However, UVs resulting in splicing alterations can be readily assessed by in vitro assays. Unfortunately, analytical and clinical interpretation of these assays is often challenging. Here, we explore this issue by conducting splicing assays in 31 BRCA2 genetic variants. All variants were assessed by RT-PCR followed by capillary electrophoresis and direct sequencing. If assays did not produce clear-cut outputs (Class-2 or Class-5 according to analytical International Agency for Research on Cancer guidelines), we performed qPCR and/or minigene assays. The latter were performed with a new splicing vector (pSAD) developed by authors of the present manuscript (patent #P201231427 CSIC). We have identified three clinically relevant Class-5 variants (c.682-2A>G, c.7617+1G>A, and c.8954-5A>G), and 27 analytical Class-2 variants (not inducing splicing alterations). In addition, we demonstrate that rs9534262 (c.7806-14T>C) is a BRCA2 splicing quantitative trait locus., (© 2013 WILEY PERIODICALS, INC.)

Recently, it has been reported that biallelic mutations in the ERCC4 (FANCQ) gene cause Fanconi anemia (FA) subtype FA-Q. To investigate the possible role of ERCC4 in breast and ovarian cancer susceptibility, as occurs with other FA genes, we screened the 11 coding exons and exon-intron boundaries of ERCC4 in 1573 index cases from high-risk Spanish familial breast and ovarian cancer pedigrees that had been tested negative for BRCA1 and BRCA2 mutations and 854 controls. The frequency of ERCC4 mutation carriers does not differ between cases and controls, suggesting that ERCC4 is not a cancer susceptibility gene. Interestingly, the prevalence of ERCC4 mutation carriers (one in 288) is similar to that reported for FANCA, whereas there are approximately 100-fold more FA-A than FA-Q patients, indicating that most biallelic combinations of ERCC4 mutations are embryo lethal. Finally, we identified additional bone-fide FA ERCC4 mutations specifically disrupting interstrand cross-link repair., (© 2013 WILEY PERIODICALS, INC.)

Germ-line mutations in the breast cancer susceptibility genes BRCA1 and BRCA2 account for a large proportion of hereditary breast/ovarian cancer families. A large number of disease-causing germ-line mutations and variants of unknown pathological significance have been identified in both genes. The majority of these variants have been studied only in genomic DNA and their effects at the mRNA level have not been reported. Our aim was to ascertain the pathological effect of six BRCA1 and two BRCA2 sequence unclassified variants by RNA analysis. Three of the BRCA1 variants are novel: IVS18+5G>A, IVS20-6_IVS20-4del and IVS22-2A>G. Three BRCA1 mutations showed aberrant splicing: Ala1693del, IVS18+5G>A and IVS22-2A>G. The variants G1706A, S1715N and IVS20-6_IVS20-4del in BRCA1, and T2515I and IVS25+9A>C in BRCA2 led to normal transcripts. We compared these RNA results with those obtained from two theoretical splicing prediction methods. The consensus values for the splice sequences (Shapiro and Senapathy 1987) involved in three of the BRCA1 splicing site variants agreed with the RNA results, lending support to the validity of this model. Moreover, we used previously established exonic splicing enhancer (ESE) sequences to ascertain whether the four exonic variants studied fell within predicted ESE motifs and whether they would disrupt ESE functions. Our results suggest that the splicing predictions based on this method are not definitive and should be considered with caution. This work highlights the importance of studying mutations at DNA and RNA levels in order to clarify their pathological effect. This information is essential for providing efficient counseling for breast/ovarian cancer families., (Copyright 2003 Wiley-Liss, Inc.)

We screened index cases from 410 Spanish breast/ovarian cancer families and 214 patients (19 of them males) with breast cancer for germ-line mutations in the BRCA1 and BRCA2 genes, using SSCP, PTT, CSGE, DGGE, and direct sequencing. We identified 60 mutations in BRCA1 and 53 in BRCA2. Of the 53 distinct mutations observed, 11 are novel and 12 have been reported only in Spanish families (41.5%). The prevalence of mutations in this set of families was 26.3%, but the percentage was higher in the families with breast and ovarian cancer (52.1%). The lowest proportion of mutations was found in the site-specific female breast cancer families (15.4%). Of the families with male breast cancer cases, 59.1% presented mutations in the BRCA2 gene. We found a higher frequency of ovarian cancer associated with mutations localized in the 5' end of the BRCA1 gene, but there was no association between the prevalence of this type of cancer and mutations situated in the ovarian cancer cluster region (OCCR) region of exon 11 of the BRCA2 gene. The mutations 187_188delAG, 330A>G, 5236G>A, 5242C>A, and 589_590del (numbered after GenBank U14680) account for 46.6% of BRCA1 detected mutations whereas 3036_3039del, 6857_6858del, 9254_9258del, and 9538_9539del (numbered after GenBank U43746) account for 56.6% of the BRCA2 mutations. The BRCA1 330A>G has a Galician origin (northwest Spain), and BRCA2 6857_6858del and 9254_9258del probably originated in Catalonia (northeast Spain). Knowledge of the spectrum of mutations and their geographical distribution in Spain will allow a more effective detection strategy in countries with large Spanish populations., (Copyright 2003 Wiley-Liss, Inc.)

A frame-shift 9254del5 mutation was independently identified in 12 families, eleven of them with Spanish ancestors, in a BRCA2 screening performed in 841 breast and/or ovarian cancer families and in 339 women with breast cancer diagnosed before the age of 40 at different centers in France and Spain. We sought to analyze in detail the haplotype and founder effects of the 9254del5 and to estimate the time of origin of the mutation. Eight polymorphic microsatellite markers and two BRCA2 polymorphisms were used for the haplotype analyses. The markers were located flanking the BRCA2 gene spanning a region of 6.1 cM. Our results suggest that these families shared a common ancestry with BRCA2 9254del5, which is a founder mutation originating in the Northeast Spanish, with an estimated age of 92 (95% CI 56-141) generations., (Copyright 2003 Wiley-Liss, Inc.)