Phenotype analysis of families with TP53 germline variants at the Center for Familial Breast and Ovarian Cancer, Cologne

PURPOSE

Tumor protein p53 (TP53) pathogenic variant (PV) carriers are identified during genetic testing for hereditary causes of cancer. PVs in TP53 are associated with the Li-Fraumeni syndrome (LFS), and thus, surveillance and preventive measures are important for TP53 PV carriers. However, the penetrance of TP53 PVs can be low if the Chompret criteria are not fulfilled. In this study, we compared the phenotypic characteristics of families that did and did not fulfill the LFS criteria according to Chompret.

METHODS

The German Consortium for Hereditary Breast and Ovarian Cancer (GC-HBOC) database was used to identify index patients with a likely pathogenic/pathogenic TP53 variant and their family members. The study investigated the type of variant, pedigree, age of onset, number of primary tumors, and histological type of BC.

RESULTS

TP53 PV were present in the index cases of 35 families, 57% (20/35) of which fulfilled the Chompret criteria. The median age of onset at first BC diagnosis was lower in families that fulfilled the Chompret criteria compared to those who did not. Four of all diseased individuals were minors (4%; 4/105) when malignancy was first diagnosed. Sarcomas and brain tumors occurred in 10% (10/105) and in 7% (7/105) of all diseased persons, respectively. BC was the most frequently occurring first tumor (60%; 62/105) and additional malignancy (45%; 20/44) in this cohort. Subsequent malignancies developed in 31% (20/65) of the individuals who fulfilled the Chompret criteria compared with 15% (6/40) of those who did not.

CONCLUSION

The tumor spectrum and age of onset found in this study showed that tumors other than BC had low disease penetrance in TP53 PV carriers identified using the GC-HBOC criteria for genetic testing.

Overall survival in the OlympiA phase III trial of adjuvant olaparib in patients with germline pathogenic variants in BRCA1/2 and high risk, early breast cancer

BACKGROUND

The randomized, double-blind OlympiA trial compared 1 year of the oral poly(adenosine diphosphate-ribose) polymerase inhibitor, olaparib, to matching placebo as adjuvant therapy for patients with pathogenic or likely pathogenic variants in germline BRCA1 or BRCA2 (gBRCA1/2pv) and high-risk, human epidermal growth factor receptor 2-negative, early breast cancer (EBC). The first pre-specified interim analysis (IA) previously demonstrated statistically significant improvement in invasive disease-free survival (IDFS) and distant disease-free survival (DDFS). The olaparib group had fewer deaths than the placebo group, but the difference did not reach statistical significance for overall survival (OS). We now report the pre-specified second IA of OS with updates of IDFS, DDFS, and safety.

PATIENTS AND METHODS

One thousand eight hundred and thirty-six patients were randomly assigned to olaparib or placebo following (neo)adjuvant chemotherapy, surgery, and radiation therapy if indicated. Endocrine therapy was given concurrently with study medication for hormone receptor-positive cancers. Statistical significance for OS at this IA required P < 0.015.

RESULTS

With a median follow-up of 3.5 years, the second IA of OS demonstrated significant improvement in the olaparib group relative to the placebo group [hazard ratio 0.68; 98.5% confidence interval (CI) 0.47-0.97; P = 0.009]. Four-year OS was 89.8% in the olaparib group and 86.4% in the placebo group (Δ 3.4%, 95% CI -0.1% to 6.8%). Four-year IDFS for the olaparib group versus placebo group was 82.7% versus 75.4% (Δ 7.3%, 95% CI 3.0% to 11.5%) and 4-year DDFS was 86.5% versus 79.1% (Δ 7.4%, 95% CI 3.6% to 11.3%), respectively. Subset analyses for OS, IDFS, and DDFS demonstrated benefit across major subgroups. No new safety signals were identified including no new cases of acute myeloid leukemia or myelodysplastic syndrome.

CONCLUSION

With 3.5 years of median follow-up, OlympiA demonstrates statistically significant improvement in OS with adjuvant olaparib compared with placebo for gBRCA1/2pv-associated EBC and maintained improvements in the previously reported, statistically significant endpoints of IDFS and DDFS with no new safety signals.

Implementation and evaluation of a nurse-led decision-coaching program for healthy breast cancer susceptibility gene (BRCA1/2) mutation carriers: a study protocol for the randomized controlled EDCP-BRCA study

Background

Female BRCA mutation carriers have an increased lifetime risk for breast and ovarian cancer compared to the general population. Women who carry this mutation have several options to deal with their cancer risk, such as risk-reducing surgeries or intensified breast cancer screening. Previous research has shown that preferences in this scenario are highly dependent on affected women’s personalities and value systems. To support these women in the decision-making process, a structured decision support consisting of decision coaching combined with a decision aid might be helpful.

Methods/design

A randomized controlled trial will be conducted in order to compare usual care with structured decision support alongside usual care. The decision support program entails nurse-led decision coaching as well as an evidence-based patient decision aid. Nurses are qualified by a 4-day training program in informed decision-making and decision coaching. Six centers for Familial Breast and Ovarian Cancer in Germany will be included in the study, with a planned sample size of 398 women.

The primary outcome is the congruence between the preferred and the actual played role in the decision-making process as measured by the Control Preferences Scale. It is hypothesized that the structured decision support will enable women to play the preferred role in the decision-making process. Secondary outcomes include the knowledge and attitudes about preventive options, decisional conflict, depression and anxiety, coping self-efficacy, impact of event, and self-concept. A process evaluation will accompany the study.

Discussion

The EDCP-BRCA study is the first study to implement and evaluate decision coaching combined with a decision aid for healthy BRCA mutation carriers worldwide.

Trial registration {2a}

DRKS-ID: DRKS00015527. Registered 30 October 2019.

Survival analysis of carboplatin added to an anthracycline/taxane-based neoadjuvant chemotherapy and HRD score as predictor of response-final results from GeparSixto

Background

In the neoadjuvant GeparSixto study, adding carboplatin to taxane- and anthracycline-based chemotherapy improved pathological complete response (pCR) rates in patients with triple-negative breast cancer (TNBC). Here, we present survival data and the potential prognostic and predictive role of homologous recombination deficiency (HRD).

Patients and methods

Patients were randomized to paclitaxel plus nonpegylated liposomal doxorubicin (Myocet®) (PM) or PM plus carboplatin (PMCb). The secondary study end points disease-free survival (DFS) and overall survival (OS) were analyzed. Median follow-up was 47.3 months. HRD was among the exploratory analyses in GeparSixto and was successfully measured in formalin-fixed, paraffin-embedded tumor samples of 193/315 (61.3%) participants with TNBC. Homologous recombination (HR) deficiency was defined as HRD score ≥42 and/or presence of tumor BRCA mutations (tmBRCA).

Results

A significantly better DFS (hazard ratio 0.56, 95% CI 0.34-0.93; P = 0.022) was observed in patients with TNBC when treated with PMCb. The improvement of OS with PMCb was not statistically significant. Additional carboplatin did not improve DFS or OS in patients with HER2-positive tumors. HR deficiency was detected in 136 (70.5%) of 193 triple-negative tumors, of which 82 (60.3%) showed high HRD score without tmBRCA. HR deficiency independently predicted pCR (ypT0 ypN0) [odds ratio (OR) 2.60, 95% CI 1.26-5.37, P = 0.008]. Adding carboplatin to PM significantly increased the pCR rate from 33.9% to 63.5% in HR deficient tumors (P = 0.001), but only marginally in HR nondeficient tumors (from 20.0% to 29.6%, P = 0.540; test for interaction P = 0.327). pCR rates with carboplatin were also higher (63.2%) than without carboplatin (31.7%; OR 3.69, 1.46-9.37, P = 0.005) in patients with high HRD score but no tmBRCA. DFS rates were improved with addition of carboplatin, both in HR nondeficient (hazard ratio 0.44, 0.17-1.17, P = 0.086) and HR deficient tumors (hazard ratio 0.49, 0.23-1.04, P = 0.059).

Conclusions

The addition of carboplatin to neoadjuvant PM improved DFS significantly in TNBC. Long-term survival analyses support the neoadjuvant use of carboplatin in TNBC. HR deficiency in TNBC and HRD score in non-tmBRCA TNBC are predictors of response. HRD does not predict for carboplatin benefit.

Inhibition of Fibrinolysis and Fibrinogenolysis in Man: Comparison of ε-Aminocaproic Acid and Kallikrein Inhibitor

Inhibitor of kallikrein and trypsin (KI) extracted from bovine parotis was compared with ε-aminocaproic acid (EACA): both substances inhibit fibrinolysis induced with streptokinase. EACA is a strong inhibitor of fibrinolysis in concentrations higher than 0, 1 mg per ml plasma. The same amount and higher concentrations are not able to inhibit completely the proteolytic-side reactions of fibrinolysis (fibrinogenolysis, diminution of factor V, rise of fibrin-polymerization-inhibitors). KI inhibits well proteolysis of plasma components in concentrations higher than 2,5 units per ml plasma. Much higher amounts of KI are needed to inhibit fibrinolysis as demonstrated by our in vivo and in vitro tests.

Combination of the two substances for clinical use is suggested. Therapeutic possibilities are discussed.

Kombinierter AHG- und PTA-Mangel

Es wird über die Kombination eines Faktor-VIII- und Faktor-XI-Mangels bei einem Patienten mit schwerer Blutungsneigung berichtet. Die Schwierigkeiten der Differentialdiagnose werden aufgezeigt und ähnliche Fälle in der Literatur diskutiert.

Die Thrombolyse-Behandlung beim akuten Myokardinfarkt – eine historische Entwicklung

Die einzelnen Etappen einer 20jährigen Geschichte der klinischen Behandlung des akuten Herzinfarktes mit Streptokinase werden gedanklich noch einmal durchlaufen. Da der Koronarverschluß in 80-90 % ein Thrombus ist, bietet sein frisches Substrat die Voraussetzung zur thrombolytischen Behandlung. Tierexperimente, klinische Untersuchungen und multizentrische Studien kontrollierter Patientenkollektive lassen schon in den sechziger Jahren erkennen, daß vor allem 3-4 Std. alte Infarkte den größten Nutzen aus einer damals ausschließlich intravenosen SK-Behandlung ziehen. Seit 1978 kann die koronare Thrombolyse angiographisch bewiesen und die günstigen Auswirkungen der rechtzeitigen Reperfusion auf das Myokard mit modernen Meßmethoden beurteilt werden. Ein Großteil der friiheren Resultate bestatigt sich heute. Die intrakoronare Kurzzeitapplikation von SK mit einem vorausgehenden intravenosen SK-Bolus erreicht in kardiologischen Zentren mit 90% die optimale Lyserate. Die fur das Gros der Infarktpatienten verbleibende systemische hochdosierte Kurzzeitlyse gelingt bisher bei 63%. Diese Rate kann moglicherweise noch verbessert werden.

Abstract P3-09-04: Beyond CHEK2 in breast cancer: Search for additional moderately penetrant risk gene variants by analyzing the oligogenic disease course in CHEK2 mutation carriers

This abstract was not presented at the symposium.

Abstract P3-09-03: Low-level gonosomal mosaicism of a de novo BRCA1 gene mutation – The origin of a constitutional mutation in a breast cancer family

Mosaicisms arise when specific cells within a developing organism mutate to result in two or more cell populations with distinct genotypes. In cases of gonosomal mosaicism a genetic variation is present in both somatic and germline cells.

Here, we describe a large Turkish breast cancer family with four affected individuals. In the Index patient (II-1; age of onset 45 years), a heterozygous deleterious frameshift mutation, c.1310dupA, p.His437Glnfs*2 in BRCA1 was identified using the TruRisk® gene panel designed by the German Consortium for Hereditary Breast and Ovarian Cancer (GC-HBOC). Predictive genetic testing showed heterozygous carrier status in the daughter (III-1).

The mutation was also analyzed in peripheral blood of the affected mother (I-1; age of onset 45 years) of the index patient by Sanger Sequencing. Interestingly, Sanger sequence did demonstrate the presence of remarkable small peaks presenting the frameshift mutation similar to a mosaic pattern. A second and third independent blood draw within a time frame of four month was tested and a mosaic signal of approximately 10 % was reproducibly detected.

In order to exclude a potential allelic drop out, independent sequencing experiments via next generation sequencing (NGS; TruRisk® gene panel) were performed. Again, the mutation was present with an allele read frequency of 12 %. No other pathogenic mutations were detected in any of the other tested breast cancer susceptibility genes.

To further examine and underscore the presence of gonosomal mosaicism different tissues should be analyzed. As no tumor material or surrounding normal breast tissue was available primary skin fibroblasts were isolated from skin biopsy. Sequencing of cultured primary fibroblasts demonstrated the absence of the familial BRCA1 mutation. With NGS-based CNV analysis as well as MLPA analysis we excluded aberrant copy numbers of BRCA1 in blood and fibroblasts.

In conclusion, our data provide striking evidence for a BRCA1 mosaicism, which is not detectable in all body cells. Due to the inheritance of the BRCA1 mutation to the next generations (II-1 and III-1), we assume the presence of a gonosomal mosaicism in the affected mother (I-1).

Additionally, the history of breast cancer onset in the family indicates that the BRCA1 mosaic mutation carrier do not necessarily have a milder phenotype compared to full heterozygotes. In this context our results implicate the importance of using highly sensitive sequencing platforms in routine diagnostics to ensure the detection of disease causing low-level mosaic mutations.Mosaicisms arise when specific cells within a developing organism mutate to result in two or more cell populations with distinct genotypes. In cases of gonosomal mosaicism a genetic variation is present in both somatic and germline cells.

Here, we describe a large Turkish breast cancer family with four affected individuals. In the Index patient (II-1; age of onset 45 years), a heterozygous deleterious frameshift mutation, c.1310dupA, p.His437Glnfs*2 in BRCA1 was identified using the TruRisk® gene panel designed by the German Consortium for Hereditary Breast and Ovarian Cancer (GC-HBOC). Predictive genetic testing showed heterozygous carrier status in the daughter (III-1).

The mutation was also analyzed in peripheral blood of the affected mother (I-1; age of onset 45 years) of the index patient by Sanger Sequencing. Interestingly, Sanger sequence did demonstrate the presence of remarkable small peaks presenting the frameshift mutation similar to a mosaic pattern. A second and third independent blood draw within a time frame of four month was tested and a mosaic signal of approximately 10 % was reproducibly detected.

In order to exclude a potential allelic drop out, independent sequencing experiments via next generation sequencing (NGS; TruRisk® gene panel) were performed. Again, the mutation was present with an allele read frequency of 12 %. No other pathogenic mutations were detected in any of the other tested breast cancer susceptibility genes.

To further examine and underscore the presence of gonosomal mosaicism different tissues should be analyzed. As no tumor material or surrounding normal breast tissue was available primary skin fibroblasts were isolated from skin biopsy. Sequencing of cultured primary fibroblasts demonstrated the absence of the familial BRCA1 mutation. With NGS-based CNV analysis as well as MLPA analysis we excluded aberrant copy numbers of BRCA1 in blood and fibroblasts.

In conclusion, our data provide striking evidence for a BRCA1 mosaicism, which is not detectable in all body cells. Due to the inheritance of the BRCA1 mutation to the next generations (II-1 and III-1), we assume the presence of a gonosomal mosaicism in the affected mother (I-1).

Additionally, the history of breast cancer onset in the family indicates that the BRCA1 mosaic mutation carrier do not necessarily have a milder phenotype compared to full heterozygotes. In this context our results implicate the importance of using highly sensitive sequencing platforms in routine diagnostics to ensure the detection of disease causing low-level mosaic mutations.

Citation Format: Bülow L, Keupp K, Richters L, Pohl E, Wappenschmidt B, Zarghooni V, Reichstein-Gnielinski S, Maringa M, Giesecke J, Rhiem K, Hahnen E, Schmutzler R. Low-level gonosomal mosaicism of a de novo BRCA1 gene mutation – The origin of a constitutional mutation in a breast cancer family [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-09-03.

Abstract P3-08-01: TruRisk® based next-generation sequencing in BRCA1/2-negative breast and ovarian cancer families reveal high mutation prevalence in additional risk genes

Background: 24% of familial breast cancer (BC) and/or ovarian cancer (OC) cases analyzed within the framework of the German Consortium for Hereditary Breast and Ovarian Cancer (GC-HBOC) are due to pathogenic BRCA1/2 mutations. However, the mutation prevalence of non-BRCA1/2 genes associated with familial BC and/or BC/OC is largely unknown. Methods: Here, we present the first NGS data generated using the GC-HBOC-designed TruRisk® gene panel. In this study a cohort of 2028 BRCA1/2 and CHEK2 c.1100delC negative index cases was analyzed which comprises consecutive patients from BC families and BC/OC families complying the inclusion criteria of the GC-HBOC. Sequencing was performed on MiSeq, NextSeq, or HiSeq devices (Illumina) using customized SureSelect XT enrichment (Agilent). Data analysis was carried out using the SeqPilot software (version 4.2.2), SophiaDDM (Version 3.5.0.12-p5.0.0) as well as an in house bioinformatics pipeline (Cologne Center for Genomics, varpipe_v2.X). The analysis of copy number variations (CNV) based on NGS-data is currently in process and not yet included in the present mutation prevalence. Results: By focusing on 22 BC/OC associated genes (ATM, BARD1, BRIP1, CDH1, CHEK2, FAM175A, FANCM, MLH1, MRE11A, MSH2, MSH6, NBN, PALB2, PMS2, PTEN, RAD50, RAD51C, RAD51D, RINT1, STK11, TP53, XRCC2), we identified 71 different deleterious variants in 104 unrelated mutation carriers derived from 2028 BC and BC/OC families (8%). Interestingly, we identified a high prevalence of ATM mutations (n=29, 1.4%) in the familial cases. Additionally mutations in PALB2 (n=27), NBN (n=9), CHEK2 (n=14), BARD1 (n=9), BRIP1 (n=10), RAD51C (n=11) were frequently observed and we confirmed FANCM (n=17) as a novel BC predisposing gene. No mutations in MLH1, MRE11A, PTEN, RAD51D, STK11 and XRCC2 were identified in our collective. Conclusions: Due to the unexpectedly high mutation prevalence in familial cases, our study highlights the importance of these genes to be included in BC/OC routine diagnostics. In contrast we found low occurrence or absence of mutations for a subset of our gene selection which requires further investigation to optimize the gene panel for diagnostic purposes. Nevertheless this approach confirms the TruRisk® gene panel as a reliable tool for this comprehensive analysis.

Citation Format: Keupp K, Richters L, Bülow L, Kröber S, Ernst C, Blümcke B, Versmold B, Waha A, Driesen J, Baasner A, Altmüller J, Thiele H, Nuernberg P, Wappenschmidt B, Neidhardt G, Rhiem K, Schmutzler R, Hahnen E, Hauke J. TruRisk® based next-generation sequencing in BRCA1/2-negative breast and ovarian cancer families reveal high mutation prevalence in additional risk genes [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-08-01.

Abstract P1-09-02: Homologous repair deficiency (HRD) as measure to predict the effect of carboplatin on survival in the neoadjuvant phase II trial GeparSixto in triple-negative early breast cancer

Introduction

Addition of carboplatin to anthracycline/taxane-based neoadjuvant chemotherapy has shown to improve pathological complete response (pCR; ypT0 ypN0) rates in patients with triple-negative breast cancer (TNBC) in two large phase II studies (GeparSixto: von Minckwitz et al, Lancet Oncol 2014, CALGB 40603: Sikov WM, J Clin Oncol 2015). Participants of the GeparSixto study showed an improvement of pCR rate from 36.9 to 53.2% (p=0.005) and DFS by absolute 9% (HR 0.56 95% CI 0.33-0.96] p=0.035) with the addition of carboplatin in the TNBC subgroup. No effect was observed in the HER2-positive subgroup. We here report results on homologous repair deficiency (HRD) status in relation to pCR and DFS in the TNBC subgroup.

Patients and Methods

In the GeparSixto trial (NCT01426880), patients were treated for 18 weeks with paclitaxel 80mg/m2 q1w and non-pegylated-liposomal doxorubicin (NPLD) 20mg/m2 q1w. Patients with TNBC (N=315) received concurrently bevacizumab 15mg/kg i.v. q2w until surgery. All patients were randomized 1:1 to receive concurrently carboplatin AUC 1.5-2 q1w vs no carboplatin. Carboplatin dose was reduced from AUC 2.0 to 1.5 by an amendment after 330 patients. Primary objective is pCR rate (ypT0 ypN0). Event free survival (EFS), and overall survival (OS) were secondary objectives. HR Deficiency status was assessed on FFPE material from pretherapeutic core biopsies. HR Deficiency was defined as either HRD score high or a BRCA mutation.

Results

HRD status was measurable in 193 of 315 TNBC patients. 101 patients of them were randomly assigned to receive carboplatin and 92 to no additional carboplatin. After median follow-up of 34.3 months 43 event free survival (EFS) events have been reported.

HR deficiency was detected in 136 (70.5%) tumors of which 79 (58.1%) showed high HRD score with intact tBRCA. HR deficiency independently predicted pCR (ypT0is ypN0) (odds ratio (OR) 2.506, CI 1.243-5.051, p=0.009). Adding carboplatin to PM significantly increased the pCR rate from 36.6% to 63.2% in HR deficient tumors with intact tBRCA (p=0.018), only marginally from 61.9% to 72.7% in BRCA mutated tumors (p=0.406), and moderately from 20.0% to 40.7% in HR non-deficient tumors (p=0.086). In general, patients with HRD deficient tumors had a better ESF than non HRD deficient ones (HR 1.805 (0.985-3.309); p=0.0526). Patients with high HRD score had an insignificant trend towards an improved EFS compared to those with low HRD score (HR 1.546 (0.764-3.127) p=0.2223). HRD deficiency did not predict carboplatin effect in patients without BRCA mutation (HR 0.8617). In multivariable analysis, only therapy, clinical nodal status before treatment, and lymphocyte predominant breast cancer were significant prognostic on EFS.

Conclusion

Within the GeparSixto study HR deficiency (either HRD score high or BRCA mutation) was associated with a higher pCR in general and an improved EFS. The effect of carboplatin could not be predicted by HR deficiency in this relatively small study. However, the results will help to understand the role of HR deficiency and the value of the HRD score in TNBC especially in patients without BRCA mutation.

Citation Format: von Minckwitz G, Timms K, Untch M, Elkin EP, Hahnen E, Fasching PA, Schneeweiss A, Salat CT, Rezai M, Blohmer J-U, Zahm D-M, Jackisch C, Gerber B, Klare P, Kümmel S, Paepke S, Schmutzler R, Chau S, Reid J, Hartman A-R, Nekljudova V, Weber KE, Loibl S. Homologous repair deficiency (HRD) as measure to predict the effect of carboplatin on survival in the neoadjuvant phase II trial GeparSixto in triple-negative early breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-09-02.

BRCA1 and BRCA2 genetic testing-pitfalls and recommendations for managing variants of uncertain clinical significance

BACKGROUND

Increasing use of BRCA1/2 testing for tailoring cancer treatment and extension of testing to tumour tissue for somatic mutation is moving BRCA1/2 mutation screening from a primarily prevention arena delivered by specialist genetic services into mainstream oncology practice. A considerable number of gene tests will identify rare variants where clinical significance cannot be inferred from sequence information alone. The proportion of variants of uncertain clinical significance (VUS) is likely to grow with lower thresholds for testing and laboratory providers with less experience of BRCA. Most VUS will not be associated with a high risk of cancer but a misinterpreted VUS has the potential to lead to mismanagement of both the patient and their relatives.

DESIGN

Members of the Clinical Working Group of ENIGMA (Evidence-based Network for the Interpretation of Germline Mutant Alleles) global consortium (www.enigmaconsortium.org) observed wide variation in practices in reporting, disclosure and clinical management of patients with a VUS. Examples from current clinical practice are presented and discussed to illustrate potential pitfalls, explore factors contributing to misinterpretation, and propose approaches to improving clarity.

RESULTS AND CONCLUSION

Clinicians, patients and their relatives would all benefit from an improved level of genetic literacy. Genetic laboratories working with clinical geneticists need to agree on a clinically clear and uniform format for reporting BRCA test results to non-geneticists. An international consortium of experts, collecting and integrating all available lines of evidence and classifying variants according to an internationally recognized system, will facilitate reclassification of variants for clinical use.

Effect of Ring Asymmetry on Pseudorotation at Five-Coordinate Phosphorus in Phosphadiazetidinones

Non-equivalence of fluorine atoms has been observed in the 19F n.m.r. spectra of 1-alkyl-1,1-difluoro-N-methyl-N′-phenyl-1,2,4-phosphadiazetidin-3-ones at -40°C but not in the spectra of analogous N,N′-dimethyl compounds and a mechanism for pseudorotation in these compounds is proposed to explain this difference.

Notizen: The Fluorine-19 NMR Spectrum of Methylthiotetrafluorophosphorane

The low-temperature 19F NMR spectrum of the stereochemically non-rigid compound, CH3SPF4, shows three fluorine environments, one for the equatorial and two for the nonequivalent axial fluorine atoms. Each of the twelve lines of the upfield 19F- (axial) resonance shows further fine structure, due to coupling between 19F and the protons of the CH3S group. The center peaks of the two multiplet components reveal apparent quintet structure which, based on a computer simulation of the 19F spectrum of CH3SPF4, is rationalized in terms of accidental overlap of two quartets.

Mass Spectroscopic Studies of Phosphorus-Fluorine Compounds. Compounds containing Five-coordinate Phosphorus

The mass spectra of a number of phosphorus-fluorine compounds containing five-covalent phosphorus have been obtained. The major fragment ions for each compound are tabulated together with some probable ion assignments.

cis-trans-Isomerie in 1,5-Diaza-2,4-Diphosphorinan-6-onen cis-trans-Isomerism in 1,5-Diaza-2,4-diphosphorinan-6-ones

The methylene-bis(dialkylaminochlorophosphines) 2a and 2b react with N,N′-dimethyl- N,N′-bis(trimethylsilyl)urea 1 to give the 1,5-diaza-2,4-diphosphorinan-6-ones, 4a and 4b, each of which exists as two isomers. Sulfuration of 4a and 4b led to the stable derivatives, 5a and 5b, which, with the help of column chromatography, were separated into pure cis- and trans-isomers. The structures were established, based upon NMR-spectroscopic, chemical and analytical data.

Phosphorus-Fluorine Chemistry, XXXI

The preparation of a series of methyl-substituted piperidyl-fluorophosphoranes is described, of general formula RR′NPF4-nPhn (where RR′N = 2-Me-piperidyl-, 3-Me-piperidyl-, or 4-Me-piperi-dyl; n = 0, 1, or 2), from the cleavage of silicon-nitrogen bonds in methyl-substituted piperidyl silanes by fluorophosphoranes. The structures of the new compounds are deduced from 19F and 31P n.m.r. data.

An N.M.R. Study of some Tertiary Butyl - Phosphorus Compounds

H1 und P31 (sowie F19, soweit zutreffend) N.M.R.-Daten werden mitgeteilt für einige Verbindungen, die tertiäre Butylgruppen an Phosphor gebunden enthalten. Es wird gezeigt, daß die Verbindung (CH3)3C · P (:O) (F) [N(CH3)2] als ein Gemisch zweier Isomerer vorliegt.

Improved Synthetic Route to Unsymmetrically Substituted Phosphinimino-phosphonium Salts. Crystal Structure of Tri-n-butyl- [tris(diethylamino)phosphinimino]phosphonium Chloride

The title compound was prepared from tri-n-butyl-chlorophosphonium chloride and N-tri-methylsilyl-tris(diethylamino)-phosphinimine. A low temperature X-ray crystal structure de­termination revealed PN bond lengths of 156.1(2) and 158.0(2) pm, with a PNP angle of 149.36(17)°.

Functional variants at the 11q13 risk locus for breast cancer regulate cyclin D1 expression through long-range enhancers

Analysis of 4,405 variants in 89,050 European subjects from 41 case-control studies identified three independent association signals for estrogen-receptor-positive tumors at 11q13. The strongest signal maps to a transcriptional enhancer element in which the G allele of the best candidate causative variant rs554219 increases risk of breast cancer, reduces both binding of ELK4 transcription factor and luciferase activity in reporter assays, and may be associated with low cyclin D1 protein levels in tumors. Another candidate variant, rs78540526, lies in the same enhancer element. Risk association signal 2, rs75915166, creates a GATA3 binding site within a silencer element. Chromatin conformation studies demonstrate that these enhancer and silencer elements interact with each other and with their likely target gene, CCND1.

Association of PHB 1630 C>T and MTHFR 677 C>T polymorphisms with breast and ovarian cancer risk in BRCA1/2 mutation carriers: results from a multicenter study

BACKGROUND

The variable penetrance of breast cancer in BRCA1/2 mutation carriers suggests that other genetic or environmental factors modify breast cancer risk. Two genes of special interest are prohibitin (PHB) and methylene-tetrahydrofolate reductase (MTHFR), both of which are important either directly or indirectly in maintaining genomic integrity.

METHODS

To evaluate the potential role of genetic variants within PHB and MTHFR in breast and ovarian cancer risk, 4102 BRCA1 and 2093 BRCA2 mutation carriers, and 6211 BRCA1 and 2902 BRCA2 carriers from the Consortium of Investigators of Modifiers of BRCA1 and BRCA2 (CIMBA) were genotyped for the PHB 1630 C>T (rs6917) polymorphism and the MTHFR 677 C>T (rs1801133) polymorphism, respectively.

RESULTS

There was no evidence of association between the PHB 1630 C>T and MTHFR 677 C>T polymorphisms with either disease for BRCA1 or BRCA2 mutation carriers when breast and ovarian cancer associations were evaluated separately. Analysis that evaluated associations for breast and ovarian cancer simultaneously showed some evidence that BRCA1 mutation carriers who had the rare homozygote genotype (TT) of the PHB 1630 C>T polymorphism were at increased risk of both breast and ovarian cancer (HR 1.50, 95%CI 1.10-2.04 and HR 2.16, 95%CI 1.24-3.76, respectively). However, there was no evidence of association under a multiplicative model for the effect of each minor allele.

CONCLUSION

The PHB 1630TT genotype may modify breast and ovarian cancer risks in BRCA1 mutation carriers. This association need to be evaluated in larger series of BRCA1 mutation carriers.