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Purpose: Because BRCA1 is a high-risk breast/ovarian cancer susceptibility gene, BRCA1 sequence variants of uncertain clinical significance (VUS) complicate genetic counseling. As most VUS are rare, reliable classification based on clinical and genetic data is often impossible. However, all pathogenic BRCA1 variants analyzed result in defective homologous recombination DNA repair (HRR). Thus, BRCA1 VUS may be categorized based on their functional impact on this pathway., Experimental Design: Two hundred thirty-eight BRCA1 VUS-comprising most BRCA1 VUS known in the Netherlands and Belgium-were tested for their ability to complement Brca1- deficient mouse embryonic stem cells in HRR, using cisplatin and olaparib sensitivity assays and a direct repeat GFP (DR-GFP) HRR assay. Assays were validated using 25 known benign and 25 known pathogenic BRCA1 variants. For assessment of pathogenicity by a multifactorial likelihood analysis method, we collected clinical and genetic data for functionally deleterious VUS and VUS occurring in three or more families., Results: All three assays showed 100% sensitivity and specificity (95% confidence interval, 83%-100%). Out of 238 VUS, 45 showed functional defects, 26 of which were deleterious in all three assays. For 13 of these 26 variants, we could calculate the probability of pathogenicity using clinical and genetic data, resulting in the identification of 7 (likely) pathogenic variants., Conclusions: We have functionally categorized 238 BRCA1 VUS using three different HRR-related assays. Classification based on clinical and genetic data alone for a subset of these variants confirmed the high sensitivity and specificity of our functional assays., (©2020 American Association for Cancer Research.)

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., (© 2019 Wiley Periodicals, Inc.)

Purpose: Classification of rare BRCA1 missense variants presents a major challenge for the counseling and treatment of patients. Variant classification can be complicated by conflicting lines of evidence. BRCA1 c.5309G>T p.(Gly1770Val) has been shown to abrogate BRCA1 protein homologous DNA repair; however, multiple sequence alignment demonstrates a lack of sequence conservation at this position, suggesting that glycine at position 1770 may not be essential for cellular maintenance in humans. We analyzed clinical information to resolve the classification of BRCA1 c.5309G>T p.(Gly1770Val)., Methods: We performed multifactorial likelihood analysis combining segregation data for 14 informative families, and breast tumor histopathological data for 17 variant carriers, ascertained through the ENIGMA consortium., Results: Bayes segregation analysis gave a likelihood ratio of 101:1 in favor of pathogenicity. The vast majority of breast tumors showed features indicative of pathogenic variant carrier status, resulting in a likelihood ratio of 15800794:1 towards pathogenicity. Despite a low prior probability of pathogenicity (0.03) based on bioinformatic prediction, multifactorial likelihood analysis including segregation and histopathology analysis gave a posterior probability of > 0.99 and final classification of Pathogenic., Conclusions: We provide evidence that BRCA1 c.5309G>T p.(Gly1770Val), previously described as a Moroccan founder variant, should be treated as a disease-causing variant despite a lack of evolutionary conservation at this amino acid position. Additionally, we stress that bioinformatic information should be used in combination with other data, either direct clinical evidence or some form of clinical calibration, to arrive at a final clinical classification.

Background: We previously showed that the BRCA1 variant c.5096G>A p.Arg1699Gln (R1699Q) was associated with an intermediate risk of breast cancer (BC) and ovarian cancer (OC). This study aimed to assess these cancer risks for R1699Q carriers in a larger cohort, including follow-up of previously studied families, to further define cancer risks and to propose adjusted clinical management of female BRCA1 *R1699Q carriers., Methods: Data were collected from 129 BRCA1 *R1699Q families ascertained internationally by ENIGMA (Evidence-based Network for the Interpretation of Germline Mutant Alleles) consortium members. A modified segregation analysis was used to calculate BC and OC risks. Relative risks were calculated under both monogenic model and major gene plus polygenic model assumptions., Results: In this cohort the cumulative risk of BC and OC by age 70 years was 20% and 6%, respectively. The relative risk for developing cancer was higher when using a model that included the effects of both the R1699Q variant and a residual polygenic component compared with monogenic model (for BC 3.67 vs 2.83, and for OC 6.41 vs 5.83)., Conclusion: Our results confirm that BRCA1 *R1699Q confers an intermediate risk for BC and OC. Breast surveillance for female carriers based on mammogram annually from age 40 is advised. Bilateral salpingo-oophorectomy should be considered based on family history., Competing Interests: Competing interests: EGG has received an honorarium in the past 3 years from AstraZeneca for giving a course and a lecture. HE (or rather, his department with him as primary contact) has received funding from Novartis Oncology (unrestricted grant) and AstraZeneca (invited speaker). KT has received an honorarium for chairing a mainstreaming genetic testing subcommittee and day seminar for AstraZeneca. AET declares to have received an honorarium from American Cancer Society for grant review, NIH NCI PDQ as editorial board, Italian Ministry of Health for grant review. DEE receives an honorarium from AstraZeneca via a contract with the university to provide consultancy advice from time to time (one or two advisory boards each year on average at the moment). DEG has received royalties from patents on the BRCA1 and BRCA2 genes from the University of Utah that are licensed to Myriad Genetics. All the other authors declare to have no conflicts of interest., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

To establish whether existing mutation prediction models can identify which male breast cancer (MBC) patients should be offered BRCA1 and BRCA2 diagnostic DNA screening, we compared the performance of BOADICEA (Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm), BRCAPRO (BRCA probability) and the Myriad prevalence table ("Myriad"). These models were evaluated using the family data of 307 Dutch MBC probands tested for BRCA1/2, 58 (19%) of whom were carriers. We compared the numbers of observed vs predicted carriers and assessed the Area Under the Receiver Operating Characteristic (ROC) Curve (AUC) for each model. BOADICEA predicted the total number of BRCA1/2 mutation carriers quite accurately (observed/predicted ratio: 0.94). When a cut-off of 10% and 20% prior probability was used, BRCAPRO showed a non-significant better performance (observed/predicted ratio BOADICEA: 0.81, 95% confidence interval [CI]: [0.60-1.09] and 0.79, 95% CI: [0.57-1.09], vs., Brcapro: 1.02, 95% CI: [0.75-1.38] and 0.94, 95% CI: [0.68-1.31], respectively). Myriad underestimated the number of carriers in up to 69% of the cases. BRCAPRO showed a non-significant, higher AUC than BOADICEA (0.798 vs 0.776). Myriad showed a significantly lower AUC (0.671). BRCAPRO and BOADICEA can efficiently identify MBC patients as BRCA1/2 mutation carriers. Besides their general applicability, these tools will be of particular value in countries with limited healthcare resources., (© 2017 The Authors. Clinical Genetics published by John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Nearly 15% of BRCA1 and BRCA2 DNA tests lead to the identification of Variants of Uncertain Significance (VUS). VUS are classified in the Netherlands according to the Bell system and it is current practice that class III VUS are communicated to counsellees, but not class II or lower VUS. Our aims were to investigate the utility of in silico characteristics in the classification of VUS and whether initial VUS classifications justify differences in communication protocols during counselling., Methods: We classified 88 missense VUS in BRCA1 and BRCA2 on the basis of an in silico analysis and compared the classification of a subset of 60 VUS of which additional information including family, genetic and tumour data was available., Results: VUS allocated to class III more frequently showed in silico indications of a deleterious effect than class II VUS. Of the 46 VUS assigned to class II by in silico analysis alone, nearly half were eventually recategorised as class I and 10% as class III when additional information was included., Conclusions: As in silico analysis alone is not always sufficient to unambiguously assign VUS to either class II or class III, we would argue that the prospect of obtaining additional information from a family should be given more weight during the decision process preceding the communication of a VUS test result. Research initiatives such as the Evidence-based Network for the Interpretation of Germline Mutant Alleles (ENIGMA), which strive to combine diverse sources of information, will be valuable in aiding a definitive classification of a VUS.