Recommendations for the implementation of genetic testing for metastatic prostate cancer patients in Canada

Introduction: Genetic testing in advanced prostate cancer is rapidly moving to become standard of care. Testing for genetic alterations in genes involved in DNA repair pathways, particularly those implicated in the homologous recombination repair (HRR) pathway, in patients with metastatic prostate cancer (mPCa) can inform selection of optimal therapies, as well as provide information about familial cancer risks. However, there are currently no consistent Canadian guidelines in place for genetic testing in mPCa. Methods: A multidisciplinary steering committee guided the process of an environmental scan to define the current landscape, as well as the perceived challenges, through interviews with specialists from 14 sites across Canada. The challenges most commonly identified include limited testing guidelines and protocols, inadequate education and awareness, and insufficient resources. Following the environmental scan, an expert multidisciplinary working group with pan-Canadian representation from medical oncologists, urologists, medical geneticists, genetic counsellors, pathologists, and clinical laboratory scientists convened in virtual meetings to discuss the challenges in implementation of genetic testing in mPCa across Canada. Results: Key recommendations from the working group include implementation of germline and tumor HRR testing for all metastatic patients, with a mainstreaming model in which non-geneticist clinicians can initiate germline testing. The working group defined the roles and responsibilities of the various health care providers (HCPs) involved in the genetic testing pathway for mPCa patients. In addition, the educational needs for all HCPs involved in the genetic testing pathway for mPCa were defined. Conclusions: As genetic testing for mPCa becomes standard of care, additional resources and investments will be required to implement the changes that will be needed to support the necessary volume of genetic testing, to ensure equitable access, and to provide education to all stakeholders.

Performance of the McGill Interactive Pediatric OncoGenetic Guidelines for Identifying Cancer Predisposition Syndromes

Importance

Prompt recognition of a child with a cancer predisposition syndrome (CPS) has implications for cancer management, surveillance, genetic counseling, and cascade testing of relatives. Diagnosis of CPS requires practitioner expertise, access to genetic testing, and test result interpretation. This diagnostic process is not accessible in all institutions worldwide, leading to missed CPS diagnoses. Advances in electronic health technology can facilitate CPS risk assessment.

Objective

To evaluate the diagnostic accuracy of a CPS prediction tool (McGill Interactive Pediatric OncoGenetic Guidelines [MIPOGG]) in identifying children with cancer who have a low or high likelihood of having a CPS.

Design, Setting, and Participants

In this international, multicenter diagnostic accuracy study, 1071 pediatric (<19 years of age) oncology patients who had a confirmed CPS (12 oncology referral centers) or who underwent germline DNA sequencing through precision medicine programs (6 centers) from January 1, 2000, to July 31, 2020, were studied.

Exposures

Exposures were MIPOGG application in patients with cancer and a confirmed CPS (diagnosed through routine clinical care; n = 413) in phase 1 and MIPOGG application in patients with cancer who underwent germline DNA sequencing (n = 658) in phase 2. Study phases did not overlap. Data analysts were blinded to genetic test results.

Main Outcomes and Measures

The performance of MIPOGG in CPS recognition was compared with that of routine clinical care, including identifying a CPS earlier than practitioners. The tool's test characteristics were calculated using next-generation germline DNA sequencing as the comparator.

Results

In phase 1, a total of 413 patients with cancer (median age, 3.0 years; range, 0-18 years) and a confirmed CPS were identified. MIPOGG correctly recognized 410 of 412 patients (99.5%) as requiring referral for CPS evaluation at the time of primary cancer diagnosis. Nine patients diagnosed with a CPS by a practitioner after their second malignant tumor were detected by MIPOGG using information available at the time of the first cancer. In phase 2, of 658 children with cancer (median age, 6.6 years; range, 0-18.8 years) who underwent comprehensive germline DNA sequencing, 636 had sufficient information for MIPOGG application. When compared with germline DNA sequencing for CPS detection, the MIPOGG test characteristics for pediatric-onset CPSs were as follows: sensitivity, 90.7%; specificity, 60.5%; positive predictive value, 17.6%; and negative predictive value, 98.6%. Tumor DNA sequencing data confirmed the MIPOGG recommendation for CPS evaluation in 20 of 22 patients with established cancer-CPS associations.

Conclusions and Relevance

In this diagnostic study, MIPOGG exhibited a favorable accuracy profile for CPS screening and reduced time to CPS recognition. These findings suggest that MIPOGG implementation could standardize and rationalize recommendations for CPS evaluation in children with cancer.

Functional study of a N-terminal CPVT mutation RyR2R420Q in patient specific hiPSC-CMs model

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): ANR (Agence Nationale de la Rercherche)

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a lethal genetic arrhythmia that manifests by syncope or sudden death in children and young adults under stress conditions without obvious cardiac structural abnormality. A novel CPVT mutation located in the RyR2 N terminal portion has been identified in a Spanish family (RyR2R420Q). According to the studies of RyR2 function in HEK293 cell line, this mutation presented gain of function at low cytosolic intracellular Ca2+ concentration ([Ca2+]i) and loss of function at high [Ca2+]i. Moreover, KI mice heterozygous for this mutation presented bradycardia and sino-atrial node (SAN) dysfunction. Here we generated induced pluripotent stem cell (hiPSC) from two brothers (one with mutation, the other without mutation as control) of this family and differentiated them into cardiomyocytes (hiPSC-CM). In order to verify that the differentiated cells were well cardiomyocytes, we did immunofluorescence labelling to detect the α-actinin expression and found that around 90% cells were α-actinin positive in both groups of hiPS-CMs. Then the calcium transient was studied by confocal microscopy and the action potential (AP) by micro-electrode technique. The characteristics of spontaneous AP of mutated cells were mostly similar to that of control cells, but more mutated cells presented proarrhythmic behaviors under adrenergic stimulation. hiPSC-CM are immature cardiomyocytes and contract spontaneously. In order to be able to analyze [Ca2+]i transient characteristics, we paced the cells at a constant rate of 1 Hz by field stimulation through two Pt electrodes. Sarcoplasmic reticulum (SR) Ca2+ load was estimated by rapid caffeine (10 mM) application. hiPSC-CMs from the RyR2R420Q carrier presented smaller SR Ca2+ load than those from the control person, whereas their fractional release (the [Ca2+]i transient normalized by the amount of Ca2+ stored in the SR) was higher than that in control group, indicating a gain-of-function mutation.  Even if SR Ca2+ load was smaller in RyR2R420Q cells, they often presented proarrhythmogenic behavior such as Ca2+ waves. The fact was further enhanced during β-adrenergic stimulation, pointing to this model as a valuable tool to study the CPVT disease in human cells.

Ca2+ handling in induced-pluripotent cardiomyocytes from female CPVT patient, and comparison to male

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Agence Nationale de la Recherche

Introduction

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is an inherited disease manifested as syncope or sudden death in apparently healthy children or young adults, in the absence of structural cardiac disease. The ryanodine receptor (RyR2) R420Q mutation was identified in a Spanish 14-year-old boy who died suddenly due to emotional stress. We generated human induced-pluripotent (h-iPS) derived cardiomyocytes from two brothers (see Yin’s poster in this meeting). As most of sudden death occurs in males, we had the hypothesis that there might be some sex-dependent differences.

Purpose and methods

We aim to elucidate the key role of [Ca2+]i in the genesis of cardiac arrhythmia in female RyR2R420Q CPVT patients . We generated here hiPSC-CM from two sisters of the same family, one exhibiting the mutation RyR2R420Q and the other without the mutation used as control. The experiments were conducted at 30-35 days after differentiation into cardiomyocytes. Using confocal microscopy, we assessed intracellular [Ca2+]i handling both spontaneous and during electrical pacing. To record [Ca2+]i transients, h-iPS-CMs were electrically field stimulated by two Pt electrodes at 1Hz. Spontaneous Ca2+ sparks and Ca2+ waves were recorded in quiescent cells, after [Ca2+]i transients recordings. For SR Ca2+ load quantification, h-iPS-CMs were rapidly perfused with 10 mmol/L caffeine. To induce β-adrenergic activation, 100nM isoproterenol (ISO) was added in some experiments. All confocal Ca2+ images analyses were performed by home-made routines using IDL software.

Results

First, we verify by immunofluorescence the expression of alpha-actinin in the differentiated h-iPS-CMs. Then, by confocal microscopy we found that woman CPVT h-iPS-CMs presented longer cycle length than wt h-iPS-CMs, correlating with the bradycardia observed in CPVT patients. The amplitude of the Ca2+ transients were significantly higher for CPVT h-iPS-CMs compared to wt; however, after ISO perfusion Ca2+ transients did not show a significant increase in CPVT h-iPS-CMs compared to CPVT h-iPS-CMs before ISO. SR Ca2+ load presented no differences between groups but the time decay constant of the caffeine-evoked Ca2+ transients were significantly faster in CPVT h-iPS-CMs whereas it became slower after ISO perfusion. In addition, analysis of Ca2+ pro-arrhythmogenic events were significantly augmented in CPVT h-iPS-CMs compared to wt h-iPS-CMs. After ISO perfusion, pro-arrhythmogenic events in CPVT cells presented no significant difference compared to CPVT cell before ISO perfusion. Although proarrhythmogenic events were similarly higher in both male and female hiPSC-CM, the Ca2+ handling characteristics were slightly different.

Conclusion

The RyR2R420Q mutation in woman CPVT h-iPS-CMs provides a reliable model to study CPVT in human context.

The Crying Clinic: Increasing accessibility to Infant Mental Health services for immigrant parents at risk for peripartum depression

Peripartum depression (PPD) is considered a major public health concern due to its profound impact on families, including infants. In this paper, we report on a pilot initiative designed to reduce barriers and stigma related to the use of traditional infant mental health services for immigrant parents deemed at high risk of PPD. The Crying Clinic (CC) is an innovative walk-in service offered in a culturally diverse Canadian community to support maternal well-being and healthy parent-infant relationships. The CC was designed to be a gateway to existing infant mental health services, through its emphasis on accessibility and cultural sensitivity. Support for concrete concerns, such as anxiety about normative infant behaviors like crying, is underscored in this approach to attract vulnerable families who would otherwise not access mental health support. A review of 44 users, utilization, plans for the use of additional services, and client evaluations suggests that the CC accomplished most of its goals. We conclude that gateway service models such as the CC have the potential to enhance traditional infant mental health programs by creatively addressing the challenge of engaging highly vulnerable parents from culturally diverse backgrounds.

Bioelectronic organ-based sensor for microfluidic real-time analysis of the demand in insulin

On-line and real-time analysis of micro-organ activity permits to use the endogenous analytical power of cellular signal transduction algorithms as biosensors. We have developed here such a sensor using only a few pancreatic endocrine islets and the avoidance of transgenes or chemical probes reduces bias and procures general usage. Nutrient and hormone-induced changes in islet ion fluxes through channels provide the first integrative read-out of micro-organ activity. Using extracellular electrodes we captured this read-out non-invasively as slow potentials which reflect glucose concentration-dependent (3-15 mM) micro-organ activation and coupling. Custom-made PDMS-based microfluidics with platinum black micro-electrode arrays required only some tens of islets and functioned at flow rates of 1-10 µl/min which are compatible with microdialysis. We developed hardware solutions for on-line real-time analysis on a reconfigurable Field-Programmable Gate Array (FPGA) that offered resource-efficient architecture and storage of intermediary processing stages. Moreover, real-time adaptive and reconfigurable algorithms accounted for signal disparities and noise distribution. Based on islet slow potentials, this integrated set-up allowed within less than 40 μs the discrimination and precise automatic ranking of small increases (2 mM steps) of glucose concentrations in real time and within the physiological glucose range. This approach shall permit further development in continuous monitoring of the demand for insulin in type 1 diabetes as well as monitoring of organs-on-chip or maturation of stem-cell derived islets.

Molecular analysis distinguishes metastatic disease from second cancers in patients with retinoblastoma

The pediatric ocular tumor retinoblastoma readily metastasizes, but these lesions can masquerade as histologically similar pediatric small round blue cell tumors. Since 98% of retinoblastomas have RB1 mutations and a characteristic genomic copy number "signature", genetic analysis is an appealing adjunct to histopathology to distinguish retinoblastoma metastasis from second primary cancer in retinoblastoma patients. Here, we describe such an approach in two retinoblastoma cases. In patient one, allele-specific (AS)-PCR for a somatic nonsense mutation confirmed that a temple mass was metastatic retinoblastoma. In a second patient, a rib mass shared somatic copy number gains and losses with the primary tumor. For definitive diagnosis, however, an RB1 mutation was needed, but heterozygous promoter→exon 11 deletion was the only RB1 mutation detected in the primary tumor. We used a novel application of inverse PCR to identify the deletion breakpoint. Subsequently, AS-PCR designed for the breakpoint confirmed that the rib mass was metastatic retinoblastoma. These cases demonstrate that personalized molecular testing can confirm retinoblastoma metastases and rule out a second primary cancer, thereby helping to direct the clinical management.

Birt-Hogg-Dubé syndrome: a large single family cohort

Background

Birt-Hogg-Dubé (BHD) syndrome is an autosomal dominant condition characterized by dermatologic lesions, pulmonary manifestations, and renal tumors. The syndrome arises from germline mutations in the folliculin (FLCN) gene. We present findings from the single largest family BHD cohort described to date. Primary objectives were to characterize cystic lung changes on computed tomography (CT) chest scanning and identify features that stratify patients at higher risk of pneumothorax. Secondary objectives entailed description of the following: type and natural history of BHD-associated pneumothorax, pulmonary function characteristics, and relationship between cystic lung changes and pulmonary function.

Methods

The study was a retrospective chart review for a case series of a single family. Over 70 family members of a proband with documented BHD were identified, 68 of which consented to genetic testing. All those with confirmed BHD were offered a clinical assessment by the Medical Genetics and Pulmonary services which included a history, physical exam, complete pulmonary function tests, and computed tomography (CT) scan of the chest and abdomen.

Results

Thirty-six individuals had a heterozygous mutation in the FLCN gene (c.59delT). Of these, 100 % (28/28) had pulmonary cysts, 41 % (13/32) had spontaneous pneumothoraces, 26 % (8/31) had kidney cysts, 3 % (1/31) had renal tumors, and 53 % (18/34) had dermatologic manifestations. Recurrent pneumothoraces were common (40 %). Cyst size (OR 3.23, 95 % CI 1.35–7.73) and extent of lower lung zone disease (OR 6.43, 95 % CI 1.41–29.2) were the only findings associated with pneumothorax. The size or extent of cystic disease did not correlate with lung function results.

Conclusions

This is the largest single family cohort of patients with BHD syndrome documented to date. We found that all individuals had pulmonary cysts, pneumothoraces were common, and cyst size and lower lobe predominant disease were associated with pneumothorax. Lung function was generally preserved and not affected by a high cyst burden.

A founder mutation in BBS2 is responsible for Bardet-Biedl syndrome in the Hutterite population: utility of SNP arrays in genetically heterogeneous disorders

Bardet-Biedl syndrome (BBS) is a multisystem genetically heterogeneous disorder, the clinical features of which are largely the consequence of ciliary dysfunction. BBS is typically inherited in an autosomal recessive fashion, and mutations in at least 14 genes have been identified. Here, we report the identification of a founder mutation in the BBS2 gene as the cause for the increased incidence of this developmental disorder in the Hutterite population. To ascertain the Hutterite BBS locus, we performed a genome-wide single nucleotide polymorphism (SNP) analysis on a single patient and his three unaffected siblings from a Hutterite family. The analysis identified two large SNP blocks that were homozygous in the patient but not in his unaffected siblings, one of these regions contained the BBS2 gene. Sequence analysis and subsequent RNA studies identified and confirmed a novel splice site mutation, c.472-2A>G, in BBS2. This mutation was also found in homozygous form in three subsequently studied Hutterite BBS patients from two different leuts, confirming that this is a founder mutation in the Hutterite population. Further studies are required to determine the frequency of this mutation and its role, if any, in the expression of other ciliopathies in this population.

Object-oriented design of medical imaging software

A special software package for interactive display and manipulation of medical images was developed at the University Hospital of Geneva, as part of a hospital wide Picture Archiving and Communication System (PACS). This software package, called Osiris, was especially designed to be easily usable and adaptable to the needs of noncomputer-oriented physicians. The Osiris software has been developed to allow the visualization of medical images obtained from any imaging modality. It provides generic manipulation tools, processing tools, and analysis tools more specific to clinical applications. This software, based on an object-oriented paradigm, is portable and extensible. Osiris is available on two different operating systems: the Unix X-11/OSF-Motif based workstations, and the Macintosh family.

Effect of undernutrition on the ability of the sheep rumen to absorb volatile fatty acids

The ability of the rumen to absorb the same quantity of VFA with 4 animals previously fed with 2 levels of intake was tested. Animals received maintenance (P1) and half maintenance (P2) energy and nitrogen requirements successively. Absorption was measured with the empty washed rumen technique. Three litres of a solution buffered at pH 6.30 containing VFA (C2:57.1, C3:49.2 and C4:7.4 mM or C2:79.8, C3:23.5 and C4:11.5 mM) and CoEDTA (7.1 mg Co/l) were introduced in the rumen and regularly sampled for 3 h. VFA absorption was linear during the trials. Rates of absorption were expressed as mmol/h or percentage of initial quantity/h for the comparison between VFA. The order of absorption rate (%/h) was C4 > C3 > C2. Water absorption was not significantly different between the periods whereas VFA absorption rates (mmol/h) were significantly reduced after undernutrition. Composition of the solution had no significant effect on VFA absorption rate (%/h).

Portable image-manipulation software: what is the extra development cost?

A hospital-wide picture archiving and communication system (PACS) project is currently under development at the University Hospital of Geneva. The visualization and manipulation of images provided by different imaging modalities constitutes one of the most challenging component of a PACS. It was necessary to provide this visualization software on a number of types of workstations because of the varying requirements imposed by the range of clinical uses it must serve. The user interface must be the same, independent of the underlying workstation. In addition to a standard set of image-manipulation and processing tools, there is a need for more specific clinical tools that can be easily adapted to specific medical requirements. To achieve this goal, it was elected to develop a modular and portable software called OSIRIS. This software is available on two different operating systems (the UNIX standard X-11/OSF-Motif based workstations and the Macintosh family) and can be easily ported to other systems. The extra effort required to design such software in a modular and portable way was worthwhile because it resulted in a platform that can be easily expanded and adapted to a variety of specific clinical applications. Its portability allows users to benefit from the rapidly evolving workstation technology and to adapt the performance to suit their needs.

A clinical molecular scanner: the Melanie project

We developed an expert system to analyze and interpret protein maps. This system, Melanie (medical electrophoresis analysis interactive expert), can distinguish between normal and cirrhotic liver and identify various types of cancer on the basis of protein patterns in biopsy specimens. Our findings suggest that some diseases associated with toxic compounds or modifications of the human genome can be diagnosed by expert systems that analyze protein maps. The combination of protein mapping and computer analysis could result in a clinically useful "molecular scanner". The massive amount of information analyzed and stored in such studies requires new strategies, including centralized databases and image transmission over networks. Increased understanding of protein expression and regulation will enhance the importance of the human genome project in medicine and biology.