Abstract P5-10-01: Using whole genome sequencing and somatic mutation signatures to unravel insight into familial breast cancer aetiology

Approximately 10-15% of breast cancers are associated with a strong family history of disease. Pathogenic variants in BRCA1, BRCA2 or other moderate to highly penetrant susceptibility genes (e.g. TP53, ATM, CHEK2, PALB2 and PTEN) account for a number of breast cancer families. However, for over 50% of families the underlying genetic contribution to their risk remains unknown (termed here as non-BRCA1/2). This has a profound impact for how individuals and their families are managed in the clinic. We applied whole genome sequencing (WGS) to determine whether somatic mutation analysis can reveal insight into the aetiology of familial breast cancer. The full repertoire of somatic mutations was evaluated in 26 BRCA1, 22 BRCA2 and 32 non-BRCA1/2 tumours; including SNPs, indels, copy number changes and structural rearrangements, and mutational signatures. Genomes were also analysed using the HRD Index and HRDetect, as predictors of homologous recombination deficiency. BRCA1, BRCA2 and non-BRCA1/2 tumours exhibited a different burden of mutations, a different spectrum of mutational signatures and different telomere length. Based on collective patterns of mutation signatures, tumours were classified as 'BRCA1-like', 'BRCA2-like' or 'non-BRCA1/2-like' with a 15% rate of tumour re-classification from their original clinical BRCA status. The results demonstrate the power of WGS to differentiate between BRCA1 and BRCA2 driven tumours; in the identification of double-pathogenic germline mutation carriers based on the resulting somatic mutation signature; and in the interpretation of BRCA unclassified variants. WGS of tumour genomes reveals fascinating insights into tumour aetiology and could compliment current genetic testing of breast cancer families.

Citation Format: Simpson P, Nones K, Johnson J, Newell F, Patch A-M, Thorne H, Kazakoff S, De Luca X, Parsons M, Ferguson K, Reid L, McCart Reed A, Srihari S, Lakis V, Davidson A, Mukhopadhyay P, Holmes O, Xu Q, Wood S, Leonard C, Beasley J, Degasperi A, Nik-Zainal S, Ragan M, Spurdle A, Khanna KK, Lakhani S, Pearson J, Chenevix-Trench G, Waddell N. Using whole genome sequencing and somatic mutation signatures to unravel insight into familial breast cancer aetiology [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-10-01.

Trends in intra-aortic balloon counterpulsation: Comparison of a 669 record Australian dataset with the multinational Benchmark Counterpulsation Outcomes Registry

The aim of this study was to review and describe indications for intraaortic balloon counterpulsation (IABP) use and identify the impact these have on outcomes at an Australian cardiothoracic tertiary referral hospital. A secondary aim was comparison of the Australian practice with a large multinational IABP data registry. Patient demographics, IABP indication, IABP complication rate and mortality in 662 patients treated with IABP at The Prince Charles Hospital (TPCH), Brisbane, between January 1994 and December 2004 inclusive were compared with The Benchmark Counterpulsation Outcomes Registry. Data were collected between 1994 and 2000 by retrospective patient record review and prospectively using the Benchmark database from 2001 to 2004. Statistical analysis was undertaken usingSAS (v8.2) software. The mean age of patients managed with IABP at TPCH (71.6% male) was 63.4 years (SD 12.4). In-hospital mortality rate was 22% and the complication rate was 10.3%. TPCH indications for IABP were: weaning from cardiopulmonary bypass (34.2%); cardiogenic shock (24.4%); preoperative support (13%); catheter laboratory support (10.6%); refractory ventricular failure (7.3%); ischaemia related to intractable ventricular arrhythmias (4.5%); unstable refractory angina (4%); mechanical complications due to acute myocardial infarction (1.2%) and other (0.4%) (0.4% not reported). In comparison to Benchmark, IABP at TPCH demonstrated a prejudice toward intraoperative use (34.2% versus 16.6%; P= <0.0001) and an aversion to catheter laboratory support (10.6% versus 19%; P= <0.0001). TPCH and Benchmark IABP outcomes demonstrated comparable mortality (22% versus 20.8%; P=ns) but increased TPCH complications (10.3% vs. 6.2%; P= <0.0001) owing to a 2% difference in observed insertion site bleeding.

Proteasome lid bridges mitochondrial stress with Cdc53/Cullin1 NEDDylation status

Cycles of Cdc53/Cullin1 rubylation (a.k.a NEDDylation) protect ubiquitin-E3 SCF (Skp1-Cullin1-F-box protein) complexes from self-destruction and play an important role in mediating the ubiquitination of key protein substrates involved in cell cycle progression, development, and survival. Cul1 rubylation is balanced by the COP9 signalosome (CSN), a multi-subunit derubylase that shows 1:1 paralogy to the 26S proteasome lid. The turnover of SCF substrates and their relevance to various diseases is well studied, yet, the extent by which environmental perturbations influence Cul1 rubylation/derubylation cycles per se is still unclear. In this study, we show that the level of cellular oxidation serves as a molecular switch, determining Cullin1 rubylation/derubylation ratio. We describe a mutant of the proteasome lid subunit, Rpn11 that exhibits accumulated levels of Cullin1-Rub1 conjugates, a characteristic phenotype of csn mutants. By dissecting between distinct phenotypes of rpn11 mutants, proteasome and mitochondria dysfunction, we were able to recognize the high reactive oxygen species (ROS) production during the transition of cells into mitochondrial respiration, as a checkpoint of Cullin1 rubylation in a reversible manner. Thus, the study adds the rubylation cascade to the list of cellular pathways regulated by redox homeostasis.

Mental Health Diagnoses, Symptoms, and Service Utilization in US Youth with Perinatal HIV Infection or HIV Exposure

Youth perinatally HIV infected (PHIV) or HIV exposed, but uninfected (PHEU), are aging into adolescence and adulthood with multiple complex risk factors for mental health (MH) problems and poor MH treatment utilization. Our aims were to estimate prevalence of MH diagnoses, clinically significant symptoms, and MH treatment utilization among youth with PHIV and among PHEU youth, 10-22 years old. We also aimed to identify correlates of diagnoses and treatment utilization. Analyses of data from standardized interviews, behavioral assessments, and chart review of 551 youth revealed that 36% had a previous or current MH diagnosis, with no significant HIV status group differences. Prevalence of clinically significant symptoms was 15% for both groups, of whom a third had no diagnosis, and half were not receiving treatment. Among youth with a current MH diagnosis, those with PHIV had greater utilization of services than PHEU youth (67% vs. 51%; p = 0.04). Factors associated with MH diagnoses and/or treatment utilization included caregiver characteristics, age and sex of child, HIV status, and stressful life events. Prevalence of MH diagnoses was higher than in the general population, but lower than in similar perinatally HIV-exposed cohorts, with some unmet service needs, particularly in PHEU youth. Family characteristics warrant careful consideration in early diagnosis and treatment of MH problems among youth affected by HIV.

Automated analysis of fetal cardiac function using color tissue Doppler imaging

OBJECTIVE

To evaluate the feasibility of automated analysis of fetal myocardial velocity recordings obtained by color tissue Doppler imaging (cTDI).

METHODS

This was a prospective cross-sectional observational study of 107 singleton pregnancies ≥ 41 weeks of gestation. Myocardial velocity recordings were obtained by cTDI in a long-axis four-chamber view of the fetal heart. Regions of interest were placed in the septum and the right (RV) and left (LV) ventricular walls at the level of the atrioventricular plane. Peak myocardial velocities and mechanical cardiac time intervals were measured both manually and by an automated algorithm and agreement between the two methods was evaluated.

RESULTS

In total, 321 myocardial velocity traces were analyzed using each method. It was possible to analyze all velocity traces obtained from the LV, RV and septal walls with the automated algorithm, and myocardial velocities and cardiac mechanical time intervals could be measured in 96% of all traces. The same results were obtained when the algorithm was run repeatedly. The myocardial velocities measured using the automated method correlated significantly with those measured manually. The agreement between methods was not consistent and some cTDI parameters had considerable bias and poor precision.

CONCLUSIONS

Automated analysis of myocardial velocity recordings obtained by cTDI was feasible, suggesting that this technique could simplify and facilitate the use of cTDI in the evaluation of fetal cardiac function, both in research and in clinical practice. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.