Heart Failure with Recovered Ejection Fraction in Patients with Vinculin Loss-of-function Variants

Predictors of myocardial recovery in heart failure (HF) are poorly understood. We explored if vinculin (VCL) variants are associated with myocardial recovery in dilated cardiomyopathy (DCM). Six infants with DCM with a VCL loss-of-function (LOF) variant were identified. Median age at diagnosis was 2 months, median LV ejection fraction was 24%, and median LV end-diastolic diameter z-score was 10.8. All patients received HF medications. Five patients (83%) showed normalization of LV function at a median age of 2.7 years. One patient progressed to end-stage HF requiring heart transplant. This case series identified a unique phenotype of HF with reduced ejection fraction at presentation that evolved to HF with recovered EF in over 80% of infant DCM cases with LOF VCL variants. These findings have prognostic implications for counseling and management of VCL-associated DCM and highlight a possible genetic basis for HF with recovered ejection fraction.

Exploring Barriers and Facilitators to Indirect Cascade Screening for Familial Hypercholesteraemia in a Paediatric/Parent Population

Background

Familial hypercholesteraemia (FH), an inherited disorder of cholesterol metabolism, has a prevalence of 1:250 and an associated 6- to 22-fold increased risk for cardiovascular disease. Despite the prevalence and availability of effective risk-reduction treatments, 90% of at-risk Canadians are undiagnosed. Indirect cascade screening from an index case is useful but the uptake is low (<4%), suggesting that barriers may exist. Using the Theoretical Domains Framework, we sought to determine barriers and facilitators among parents of children diagnosed with FH that may influence the uptake of cascade screening among families.

Methods

A qualitative description approach was used for virtual interviews with 10 parents of children with FH, recruited from a regional Lipid Clinic in Toronto, Canada. Semistructured interviews were conducted. The data were analysed using a directed content analysis method.

Results

Five interconnecting themes were identified that captured both facilitators and barriers of indirect cascade screening: a high level of knowledge about FH after clinic attendance; parents' surprise of their child's diagnosis and ongoing worry; parents' willingness to communicate the need for cholesterol screening; parents' desire for educational materials, dictated by an external vs internal locus of control; and social and societal influences including the lack of awareness about FH in professional and public domains.

Conclusions

The themes identified will inform next steps in programme development. An urgent need was identified for strategies to educate the public and primary care providers about FH and blood cholesterol/genetic screening.

Barriers in applying to genetic counseling Master's degree programs: Perceptions of prospective applicants when compared with Canadian admissions committee members

The goal of this study was to identify potential barriers in applying to a genetic counseling (GC) Master's degree program to inform strategies for increasing diversity and inclusiveness in the GC student recruitment process. Participants included prospective GC program applicants and admissions committee members from the four Canadian accredited programs. The study was conducted using a quantitative survey-based approach. Twenty-five prospective applicants who previously applied to a GC Master's degree program, 26 who had not applied, and 48 admissions committee members completed the survey. The small number of positions in GC programs was perceived by all groups as highly likely to impact an applicant's ability to gain acceptance to a program as was the limited number of GC training programs. Prospective applicants perceived additional barriers as significantly more likely to impact an individual's ability to apply to/attend a program when compared with admissions committee members including: cost of the application process, the applicant being a visible minority and the applicant having a physical disability. These findings highlight a number of perceived barriers related to applying to a GC Master's degree program. To our knowledge, this is the first study surveying prospective applicants and admissions committee members on barriers faced during the application process. The data from this study can also be used to inform the application process for other health professions.

"Acquired" Brugada syndrome in a cardiac allograft

INTRODUCTION

Brugada syndrome is an inherited channelopathy characterized by arrhythmia and an increased risk of sudden cardiac death (SCD). Implantation of a defibrillator for primary or secondary prevention is the only effective strategy to decrease the risk of SCD in Brugada syndrome. We present a case in which a cardiac donor had a pathogenic variant for Brugada syndrome, discovered on genetic testing after transplantation.

CASE REPORT

A young child with dilated cardiomyopathy underwent orthotopic heart transplantation from a donor with in-hospital cardiac arrest in the context of fever and a normal ECG. Approximately 1 month after transplant, the donor's post mortem genetic testing revealed a pathogenic loss-of-function SCN5A variant associated with Brugada syndrome, which was confirmed on genetic testing on a post-transplant endomyocardial biopsy from the recipient. The recipient's post-transplant electrocardiographic monitoring revealed persistent right bundle branch block and progressive, asymptomatic sinus node dysfunction. The recipient was managed with precautionary measures including aggressive fever management, avoidance of drugs that increase arrhythmia risk in Brugada syndrome, and increased frequency of arrhythmia surveillance. The recipient remains asymptomatic at over 3 years post-transplant with preserved graft function and no documented ventricular arrhythmias.

CONCLUSION

We describe the clinical course of "acquired" Brugada syndrome in a cardiac allograft recipient, which has not been previously reported. The time-sensitive nature of donor organ selection, especially in critically ill recipients, combined with the growing use of molecular autopsies in patients with unexplained etiologies for death may increasingly result in important donor genetic information being made available after transplantation.

Return of Results Policies for Genomic Research: Current Practices & The Hearts in Rhythm Organization Approach

Research teams developing biobanks and/or genomic databases must develop policies for the disclosure and reporting of potentially actionable genomic results to research participants. Currently, a broad range of approaches to the return of results exist, with some studies opting for non-disclosure of research results while others follow clinical guidelines for the return of potentially actionable findings from sequencing. In this review, we describe current practices and highlight decisions a research team must make when designing a return of results policy, from informed consent to disclosure practices and clinical validation options. The unique challenges of returning incidental findings in cardiac genes, including reduced penetrance and the lack of clinical screening standards for phenotype-negative individuals are discussed. Lastly, the National Hearts in Rhythm Organization (HiRO) Registry approach is described to provide a rationale for the selective return of field-specific variants to those participating in disease-specific research. Our goal is to provide researchers with a resource when developing a return of results policy tailored for their research program, based on unique factors related to study design, research team composition and availability of clinical resources.

Development and evaluation of decision aids to guide families' predictive testing choices for children at risk for arrhythmia or cardiomyopathy

BACKGROUND

Assessing the issues surrounding predictive genetic testing for children at risk of an inherited arrythmia or cardiomyopathy is complex. The objective of this study was to design and evaluate four cardiac decision aids. The decision aids were developed to assist families with a genetic diagnosis of long QT syndrome, hypertrophic cardiomyopathy, dilated cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy in deciding between predictive genetic testing and cardiac screening for their children.

METHOD/RESULTS

The decision aids were developed using the International Patient Decision Aid Standards framework and revised based on feedback from individuals with lived experience, genetic counsellors and other healthcare professionals. Response to the decision aids was positive and acceptability and understandability scores were high.

CONCLUSION

The decision aids can be used before, during or following a genetic counselling appointment as a resource or to guide discussion. These tools permit a balanced and consistent approach to the decision-making process, with a focus on the importance families place on the advantages and disadvantages of each option.

Family screening for hypertrophic cardiomyopathy: Is it time to change practice guidelines?

Aims

Current guidelines recommend initiating family screening for hypertrophic cardiomyopathy (HCM) after age 10 or 12 years unless early screening criteria are met. The aim was to evaluate if current screening guidelines miss early onset disease.

Methods and results

Children who underwent family screening for HCM before age 18 years were analysed. Major cardiac events (MaCEs) were defined as death, sudden cardiac death (SCD), or need for major cardiac interventions (myectomy, implantable cardioverter-defibrillator insertion, transplantation). Of 524 children screened, 331 were under 10 years of age, 9.9% had echocardiographic evidence of HCM, and 1.1% were symptomatic at first screening. The median (interquartile range) age at HCM onset was 8.9 (4.7–13.4) years, and at MaCE was 10.9 (8.5–14.3) years with a median time to MaCE from HCM onset of 1.5 (0.5–4.1) years. About 52.5% phenotype-positive children and 41% with MaCEs were <10 years old. Only 69% children with early HCM met early screening criteria. Cox regression identified male gender, family history of SCD, and pathogenic variants in MYH7/MYBPC3 as a predictor of early onset HCM and MaCEs.

Conclusion

A third of children not eligible for early screening by current guidelines had phenotype-positive HCM. MYH7 and MYBC3 mutation-positive patients were at highest risk for developing early HCM and experiencing an event or requiring a major intervention. Our findings suggest that younger family members should be considered for early clinical and genetic screening to identify the subset in need of closer monitoring and interventions.

Return of genetic and genomic research findings: experience of a pediatric biorepository

Background

Assess process, uptake, validity and resource needs for return of actionable research findings to biobank participants.

Methods

Participants were prospectively enrolled in a multicenter biorepository of childhood onset heart disease. Clinically actionable research findings were reviewed by a Return of Research Results Committee (RRR) and returned to the physician or disclosed directly to the participant through a research genetic counselor. Action taken following receipt of this information was reviewed.

Results

Genetic data was generated in 1963 of 7408 participants. Fifty-nine new findings were presented to the RRR committee; 20 (34%) were deemed reportable. Twelve were returned to the physician, of which 7 were disclosed to participants (median time to disclosure, 192 days). Seven findings were returned to the research genetic counselor; all have been disclosed (median time to disclosure, 19 days). Twelve families (86%) opted for referral to clinical genetics after disclosure of findings; 7 results have been validated, 5 results are pending. Average cost of return and disclosure per reportable finding incurred by the research program was $750 when utilizing a research genetic counselor; clinical costs associated with return were not included.

Conclusions

Return of actionable research findings was faster if disclosed directly to the participant by a research genetic counselor. There was a high acceptability amongst participants for receiving the findings, for referral to clinical genetics, and for clinical validation of research findings, with all referred cases being clinically confirmed.

ALU transposition induces familial hypertrophic cardiomyopathy

Background

Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy (LVH) in the absence of predisposing cardiovascular conditions. Pathogenic variants in at least 16 cardiac sarcomeric genes have been implicated in HCM, most of which act in a dominant‐negative fashion. However loss‐of‐function (haploinsufficiency) is the most common disease mechanism for pathogenic variants in MYBPC3, suggesting that MYBPC3 complete deletion may play a role in HCM pathogenesis. Here, we investigate MYBPC3 complete deletion as a disease mechanism in HCM by analyzing two unrelated patients with confirmed diagnosis of HCM that tested negative by Sanger sequencing analysis.

Methods

MYBPC3 complete deletion was investigated by Multiplex ligation‐dependent probe amplification (MLPA) and microarray analyses. The mechanism of deletion was investigated by interrogating the SINEBase database.

Results

Patient‐1 was diagnosed with nonobstructive HCM in his mid‐40s while undergoing assessment for palpitations, and patient‐2 with obstructive HCM in his late‐20s while undergoing systolic heart murmur assessment for an unrelated illness. MLPA testing revealed a heterozygous deletion of all MYBPC3 exons in both patients. Subsequent microarray testing confirmed these deletions which extended beyond the 5′ and 3′ ends of MYBPC3. Genomic assessment suggested that these deletions resulted from Alu/Alu‐homologous recombination.

Conclusion

Our results demonstrate that haploinsufficiency resulting from MYBPC3 complete deletion, potentially mediated by Alu recombination, is an important disease mechanism in cardiomyopathy and emphasizes the importance of copy number variation analysis in patients clinically suspected of HCM.

Mutations in TOP3A Cause a Bloom Syndrome-like Disorder

Bloom syndrome, caused by biallelic mutations in BLM, is characterized by prenatal-onset growth deficiency, short stature, an erythematous photosensitive malar rash, and increased cancer predisposition. Diagnostically, a hallmark feature is the presence of increased sister chromatid exchanges (SCEs) on cytogenetic testing. Here, we describe biallelic mutations in TOP3A in ten individuals with prenatal-onset growth restriction and microcephaly. TOP3A encodes topoisomerase III alpha (TopIIIα), which binds to BLM as part of the BTRR complex, and promotes dissolution of double Holliday junctions arising during homologous recombination. We also identify a homozygous truncating variant in RMI1, which encodes another component of the BTRR complex, in two individuals with microcephalic dwarfism. The TOP3A mutations substantially reduce cellular levels of TopIIIα, and consequently subjects' cells demonstrate elevated rates of SCE. Unresolved DNA recombination and/or replication intermediates persist into mitosis, leading to chromosome segregation defects and genome instability that most likely explain the growth restriction seen in these subjects and in Bloom syndrome. Clinical features of mitochondrial dysfunction are evident in several individuals with biallelic TOP3A mutations, consistent with the recently reported additional function of TopIIIα in mitochondrial DNA decatenation. In summary, our findings establish TOP3A mutations as an additional cause of prenatal-onset short stature with increased cytogenetic SCEs and implicate the decatenation activity of the BTRR complex in their pathogenesis.

The use of family history questionnaires: an examination of genetic risk estimates and genetic testing eligibility in the non-responder population

The use of mailed family history questionnaires (FHQs) has previously been established to be an effective method for obtaining family history information for the triage of patients for genetic counseling and genetic testing of hereditary breast and ovarian cancer syndrome; yet only 53% of patients complete their FHQ within 6 months from the date of mailing (Armel et al. Journal of Genetic Counseling, 18(4):366-378, 2009). Although literature exists evaluating why women may not attend genetic counseling, no data are currently available examining genetic risk or genetic testing eligibility in the population of patients not returning their FHQ (non-responders). Concern exists that if non-responders are not followed-up for the purpose of triage for genetic counseling, individuals at high-risk for a hereditary cancer syndrome may be missed. This article explores the demographics of the non-responder population to assess genetic risk estimates for mutations in the BRCA1 and BRCA2 genes and genetic testing eligibility as compared to a responder population of patients who completed a mailed FHQ. A total of 430 pedigrees were obtained, 215 from non-responders and 215 from responders. Results of this study indicate that 69% of non-responders were either unreachable by telephone (42%), declined an appointment (19%), or were previously seen in another center for a genetic counseling visit (8%). Additionally, results indicate that non-responders are less likely to be eligible for genetic testing (40%) as compared to responders (57%) (p = 0.0004). Together these data shed light on a population of patients for which limited information exists and suggest that we question how and to what extent clinics should pursue non-responders, particularly in light of global reductions in health care funding.