Genome-wide enhancer-associated tandem repeats are expanded in cardiomyopathy.

BACKGROUND: Cardiomyopathy is a clinically and genetically heterogeneous heart condition that can lead to heart failure and sudden cardiac death in childhood. While it has a strong genetic basis, the genetic aetiology for over 50% of cardiomyopathy cases remains unknown. METHODS: In this study, we analyse the characteristics of tandem repeats from genome sequence data of unrelated individuals diagnosed with cardiomyopathy from Canada and the United Kingdom (n = 1216) and compare them to those found in the general population. We perform burden analysis to identify genomic and epigenomic features that are impacted by rare tandem repeat expansions (TREs), and enrichment analysis to identify functional pathways that are involved in the TRE-associated genes in cardiomyopathy. We use Oxford Nanopore targeted long-read sequencing to validate repeat size and methylation status of one of the most recurrent TREs. We also compare the TRE-associated genes to those that are dysregulated in the heart tissues of individuals with cardiomyopathy. FINDINGS: We demonstrate that tandem repeats that are rarely expanded in the general population are predominantly expanded in cardiomyopathy. We find that rare TREs are disproportionately present in constrained genes near transcriptional start sites, have high GC content, and frequently overlap active enhancer H3K27ac marks, where expansion-related DNA methylation may reduce gene expression. We demonstrate the gene silencing effect of expanded CGG tandem repeats in DIP2B through promoter hypermethylation. We show that the enhancer-associated loci are found in genes that are highly expressed in human cardiomyocytes and are differentially expressed in the left ventricle of the heart in individuals with cardiomyopathy. INTERPRETATION: Our findings highlight the underrecognized contribution of rare tandem repeat expansions to the risk of cardiomyopathy and suggest that rare TREs contribute to ∼4% of cardiomyopathy risk. FUNDING: Government of Ontario (RKCY), The Canadian Institutes of Health Research PJT 175329 (RKCY), The Azrieli Foundation (RKCY), SickKids Catalyst Scholar in Genetics (RKCY), The University of Toronto McLaughlin Centre (RKCY, SM), Ted Rogers Centre for Heart Research (SM), Data Sciences Institute at the University of Toronto (SM), The Canadian Institutes of Health Research PJT 175034 (SM), The Canadian Institutes of Health Research ENP 161429 under the frame of ERA PerMed (SM, RL), Heart and Stroke Foundation of Ontario & Robert M Freedom Chair in Cardiovascular Science (SM), Bitove Family Professorship of Adult Congenital Heart Disease (EO), Canada Foundation for Innovation (SWS, JR), Canada Research Chair (PS), Genome Canada (PS, JR), The Canadian Institutes of Health Research (PS).

Quick, Effective Screening Tasks Identify Children With Medical Conditions or Disabilities Needing Physical Literacy Support.

PURPOSE: This study evaluated screening tasks able to identify children with medical conditions or disabilities who may benefit from physical literacy. METHOD: Children completed ≤20 screening tasks during their clinic visit and then the Canadian Assessment of Physical Literacy (2nd edition) at a separate visit. Total Canadian Assessment of Physical Literacy scores <30th percentile were categorized as potentially needing physical literacy support. Receiver operator characteristic curves identified assessment cut points with 80% sensitivity and 40% specificity relative to total physical literacy scores. RESULTS: 223 children (97 girls; 10.1 [2.6] y) participated. Physical activity adequacy, predilection, and physical competence achieved ≥80% sensitivity and ≥40% specificity in both data sets. Adequacy ≤ 6.5 had 86% to 100% sensitivity and 48% to 49% specificity. Daily screen time >4.9 hours combined with Adequacy ≤6.15 had 88% to 10% sensitivity and 53% to 56% specificity. CONCLUSIONS: Activity adequacy, alone or with screen time, most effectively identified children likely to benefit from physical literacy support. Adequacy and screen time questionnaires are suitable for clinical use. Similar results regardless of diagnosis suggest physical competence deficits are not primary determinants of active lifestyles. Research to enhance screening specificity is required.

Age and Sex Differences in the Genetics of Cardiomyopathy.

Cardiomyopathy has variable penetrance. We analyzed age and sex-related genetic differences in 1,397 cardiomyopathy patients (Ontario, UK) with whole genome sequencing. Pediatric cases (n = 471) harbored more deleterious protein-coding variants in Tier 1 cardiomyopathy genes compared to adults (n = 926) (34.6% vs 25.9% respectively, p = 0.0015), with variant enrichment in constrained coding regions. Pediatric patients had a higher burden of sarcomere and lower burden of channelopathy gene variants compared to adults. Specifically, pediatric patients had more MYH7 and MYL3 variants in hypertrophic cardiomyopathy, and fewer TTN truncating variants in dilated cardiomyopathy. MYH7 variants clustered in the myosin head and neck domains in children. OBSCN was a top mutated gene in adults, enriched for protein-truncating variants. In dilated cardiomyopathy, female patients had a higher burden of z-disc gene variants compared to males. Genetic differences may explain age and sex-related variability in cardiomyopathy penetrance. Genotype-guided predictions of age of onset can inform pre-test genetic counseling. Pediatric cardiomyopathy patients were more likely to be genotype-positive than adults with a higher burden of variants in MYH7, MYL3, TNNT2, VCL. Adults had a higher burden of OBSCN and TTN variants. Females with dilated cardiomyopathy (DCM) had a higher burden of z-disc gene variants compared to males.

Association between maternal marginalization and infants born with congenital heart disease in Ontario Canada.

BACKGROUND: This study aims to evaluate the impact of socioeconomic status (SES) on the risk of congenital heart disease (CHD) since previous studies have yielded inconsistent results. METHODS: We conducted a population-based retrospective cohort study, including all singleton live and still births in Ontario hospitals from April 1, 2012, to March 31, 2018. We used linked records from the Better Outcomes Registry & Network Information System, the Canadian Institute for Health Information databases, and the Ontario Marginalization Index (ON_Marg). ON_Marg was estimated at a dissemination area level using Canadian Census 2016 data and categorized into quintiles. Multivariable logistic regression models were performed to examine the relationships between four ON_Marg indices (material deprivation, dependency, ethnic concentration, residential instability), as proxies for maternal SES and the risk of infant CHD. We adjusted for maternal age at birth, assisted reproductive technology, obesity, pre-existing health conditions, substance use during pregnancy, mental health conditions before and during pregnancy, rural residence, and infant's sex in the analysis. RESULTS: Among the cohort of 776,799 singletons, 9,359 infants had a diagnosis of CHD. Of those, 3,069 were severe CHD and 493 cases were single ventricle CHD. The prevalence of all infant CHD types was higher for males relative to females. Compared to mothers living in neighbourhoods with the lowest material deprivation, mothers with highest material deprivation had a 27% (adjusted OR = 1.27; 95% CI: 1.18-1.37) higher odds of having an infant diagnosed with CHD. Mothers living in neighbourhoods with the highest minority ethnic and immigrant concentration tend to have infants with 11% lower odds of CHD (adjusted OR = 0.89; 95% CI: 0.82-0.97) as compared to those living in the least ethnically diverse communities. Maternal dependency and residential stability quintiles were not significantly associated with the risk of CHD. CONCLUSION: Higher maternal material deprivation was associated with increasing odds of infant CHD, whereas neighbourhood minority ethnic concentration was inversely associated with the odds of infant CHD. Our study further confirms that poverty is associated with CHD development. Future investigations might focus on the causal pathways between social deprivation, immigrant status, ethnicity, and the risk of infant CHD.

Pedometer Efficacy for Clinical Care in Pediatric Cardiology.

BACKGROUND: Physical activity is essential to the long-term health of children living with cardiac disease. The simplicity and cost of pedometers make them an attractive alternative to accelerometers for monitoring the physical activity behaviors of these children. This study compared measures obtained from commercial-grade pedometers and accelerometers. METHODS: Pediatric cardiology outpatients (n = 41, mean age = 8.4 [3.7] y, 61% female) wore a pedometer and accelerometer daily for 1 week. Step counts and minutes of moderate to vigorous physical activity were compared between devices, accounting for age group, sex, and diagnostic severity, using univariate analysis of variance. RESULTS: While pedometer data were significantly correlated with accelerometers (r > .74, P < .001), measurements obtained were significantly different between devices. Overall, pedometers overestimated physical activity data. The overestimation of moderate to vigorous physical activity was significantly less among adolescents than younger age groups (P < .01, ηp2=.38). For step counts, there was a significant age by sex interaction observed where preschool and adolescent males tended to have greater differences between accelerometer and step count data than females (P < .01, ηp2=.33). Differences between devices were not associated with severity of diagnosis. CONCLUSIONS: The distribution of pedometers in a pediatric outpatient clinic was feasible, yet the data collected significantly overestimated physical activity, especially among younger children. Practitioners who want to introduce objective measurements as part of their physical activity counseling practice should use pedometers to monitor individual changes in physical activity and consider patient age before administering these devices for clinical care.

In Utero Enzyme-Replacement Therapy for Infantile-Onset Pompe's Disease.

Patients with early-onset lysosomal storage diseases are ideal candidates for prenatal therapy because organ damage starts in utero. We report the safety and efficacy results of in utero enzyme-replacement therapy (ERT) in a fetus with CRIM (cross-reactive immunologic material)-negative infantile-onset Pompe's disease. The family history was positive for infantile-onset Pompe's disease with cardiomyopathy in two previously affected deceased siblings. After receiving in utero ERT and standard postnatal therapy, the current patient had normal cardiac and age-appropriate motor function postnatally, was meeting developmental milestones, had normal biomarker levels, and was feeding and growing well at 13 months of age.

Associations of congenital heart disease with deprivation index by rural-urban maternal residence: a population-based retrospective cohort study in Ontario, Canada.

BACKGROUND: The risk of congenital heart disease (CHD) has been found to vary by maternal socioeconomic status (SES) and rural-urban residence. In this study, we examined associations of CHD with two maternal SES indicators and stratified the analysis by maternal rural-urban residence. METHODS: This was a population-based retrospective cohort study. We included all singleton stillbirths and live hospital births from April 1, 2012 to March 31, 2018 in Ontario, Canada. We linked the BORN Information System and Canadian Institute for Health Information databases. Multivariable logistic regression models were used to examine associations of CHD with material deprivation index (MDI), social deprivation index (SDI), and maternal residence while adjusting for maternal age at birth, assisted reproductive technology, obesity, pre-pregnancy maternal health conditions, mental health illness before and during pregnancy, substance use during pregnancy, and infant's sex. MDI and SDI were estimated at a dissemination area level in Ontario and were categorized into quintiles (Q1-Q5). RESULTS: This cohort study included 798,173 singletons. In maternal urban residence, the p trend (Cochran-Armitage test) was less than 0.0001 for both MDI and SDI; while for rural residence, it was 0.002 and 0.98, respectively. Infants living in the most materially deprived neighbourhoods (MDI Q5) had higher odds of CHD (aOR: 1.21, 95% CI: 1.12-1.29) compared to Q1. Similarly, infants living in the most socially deprived neighbourhoods (SDI Q5) had an 18% increase in the odds of CHD (aOR: 1.18, 95% CI: 1.1-1.26) compared to Q1. Rural infants had a 13% increase in the odds of CHD compared to their urban counterparts. After stratifying by maternal rural-urban residence, we still detected higher odds of CHD with two indices in urban residence but only MDI in rural residence. CONCLUSION: Higher material and social deprivation and rural residence were associated with higher odds of CHD. Health interventions and policies should reinforce the need for optimal care for all families, particularly underprivileged families in both rural and urban regions. Future studies should further investigate the effect of social deprivation on the risk of CHD development.

Whole genome sequencing delineates regulatory, copy number, and cryptic splice variants in early onset cardiomyopathy.

Cardiomyopathy (CMP) is a heritable disorder. Over 50% of cases are gene-elusive on clinical gene panel testing. The contribution of variants in non-coding DNA elements that result in cryptic splicing and regulate gene expression has not been explored. We analyzed whole-genome sequencing (WGS) data in a discovery cohort of 209 pediatric CMP patients and 1953 independent replication genomes and exomes. We searched for protein-coding variants, and non-coding variants predicted to affect the function or expression of genes. Thirty-nine percent of cases harbored pathogenic coding variants in known CMP genes, and 5% harbored high-risk loss-of-function (LoF) variants in additional candidate CMP genes. Fifteen percent harbored high-risk regulatory variants in promoters and enhancers of CMP genes (odds ratio 2.25, p = 6.70 × 10-7 versus controls). Genes involved in α-dystroglycan glycosylation (FKTN, DTNA) and desmosomal signaling (DSC2, DSG2) were most highly enriched for regulatory variants (odds ratio 6.7-58.1). Functional effects were confirmed in patient myocardium and reporter assays in human cardiomyocytes, and in zebrafish CRISPR knockouts. We provide strong evidence for the genomic contribution of functionally active variants in new genes and in regulatory elements of known CMP genes to early onset CMP.

Association of maternal socioeconomic status and race with risk of congenital heart disease: a population-based retrospective cohort study in Ontario, Canada.

OBJECTIVE: To investigate the interrelationships between maternal socioeconomic status (SES), race and congenital heart diseases (CHD) among infants. DESIGN: Retrospective cohort study. STUDY SETTING: Ontario, Canada. STUDY POPULATION: All singleton stillbirths and live births born in hospitals between 1 April 2012 and 31 March 2018 in Ontario, Canada (n=804 292). OUTCOME: CHD. ANALYSIS: Multivariable logistic regression models were performed to assess associations between maternal neighbourhood household income, education level, race and CHD while adjusting for maternal age at birth, assisted reproductive technology, obesity, pre-existing health conditions, substance use during pregnancy, maternal rural residence and infant's sex. RESULTS: Compared with infants whose mothers lived in the highest median household income neighbourhoods, infants whose mothers lived in the lowest median income neighbourhoods had a higher likelihood of having CHD (adjusted OR 1.15, 95% CI 1.06 to 1.24). Compared with infants whose mothers lived in neighbourhoods with more people with a university or higher degree, those infants whose mothers lived in neighbourhoods with less people with a university or higher degree had a higher chance of developing CHD (adjusted OR 1.26, 95% CI 1.16 to 1.36). Compared with white mothers, black mothers had a higher odds of giving birth to a child with CHD (adjusted OR 1.40, 95% CI 1.27 to 1.54). No association was detected between White and Asian mothers and CHD among infants. CONCLUSIONS: Our study indicates that there are inequities in CHD burden by maternal SES and race in Ontario, Canada. Further investigation is needed to examine racial variation in CHD using more detailed ethnic data.

Outcome of Antibody-Mediated Fetal Heart Disease With Standardized Anti-Inflammatory Transplacental Treatment.

Background Transplacental fetal treatment of immune-mediated fetal heart disease, including third-degree atrioventricular block (AVB III) and endocardial fibroelastosis, is controversial. Methods and Results To study the impact of routine transplacental fetal treatment, we reviewed 130 consecutive cases, including 108 with AVB III and 22 with other diagnoses (first-degree/second-degree atrioventricular block [n=10]; isolated endocardial fibroelastosis [n=9]; atrial bradycardia [n=3]). Dexamethasone was started at a median of 22.4 gestational weeks. Additional treatment for AVB III included the use of a ß-agonist (n=47) and intravenous immune globulin (n=34). Fetal, neonatal, and 1-year survival rates with AVB III were 95%, 93%, and 89%, respectively. Variables present at diagnosis that were associated with perinatal death included an atrial rate <90 beats per minute (odds ratio [OR], 258.4; 95% CI, 11.5-5798.9; P<0.001), endocardial fibroelastosis (OR, 28.9; 95% CI, 1.6-521.7; P<0.001), fetal hydrops (OR, 25.5; 95% CI, 4.4-145.3; P<0.001), ventricular dysfunction (OR, 7.6; 95% CI, 1.5-39.4; P=0.03), and a ventricular rate <45 beats per minute (OR, 12.9; 95% CI, 1.75-95.8; P=0.034). At a median follow-up of 5.9 years, 85 of 100 neonatal survivors were paced, and 1 required a heart transplant for dilated cardiomyopathy. Cotreatment with intravenous immune globulin was used in 16 of 22 fetuses with diagnoses other than AVB III. Neonatal and 1-year survival rates of this cohort were 100% and 95%, respectively. At a median age of 3.1 years, 5 of 21 children were paced, and all had normal ventricular function. Conclusions Our findings reveal a low risk of perinatal mortality and postnatal cardiomyopathy in fetuses that received transplacental dexamethasone±other treatment from the time of a new diagnosis of immune-mediated heart disease.

Characterization of physical literacy in children with chronic medical conditions compared with healthy controls: a cross-sectional study.

To determine the physical literacy, defined as the capability for a physically active lifestyle, of children with medical conditions compared with healthy peers, this multicenter cross-sectional study recruited children with medical conditions from cardiology, neurology (including concussion), rheumatology, mental health, respirology, oncology, hematology, and rehabilitation (including cerebral palsy) clinics. Participants aged 8-12 years (N = 130; mean age: 10.0 ± 1.44 years; 44% female) were randomly matched to 3 healthy peers from a normative database, based on age, gender, and month of testing. Total physical literacy was assessed by the Canadian Assessment of Physical Literacy, a validated assessment of physical literacy measuring physical competence, daily behaviour, knowledge/understanding, and motivation/confidence. Total physical literacy mean scores (/100) did not differ (t(498) = -0.67; p = 0.44) between participants (61.0 ± 14.2) and matched healthy peers (62.0 ± 10.7). Children with medical conditions had lower mean physical competence scores (/30; -6.5 [-7.44 to -5.51]; p < 0.001) but higher mean motivation/confidence scores (/30; 2.6 [1.67 to 3.63]; p < 0.001). Mean daily behaviour and knowledge/understanding scores did not differ from matches (/30; 1.8 [0.26 to 3.33]; p = 0.02;/10; -0.04 [-0.38 to 0.30]; p = 0.81; respectively). Children with medical conditions are motivated to be physically active but demonstrate impaired movement skills and fitness, suggesting the need for targeted interventions to improve their physical competence. Novelty: Physical literacy in children with diverse chronic medical conditions is similar to healthy peers. Children with medical conditions have lower physical competence than healthy peers, but higher motivation and confidence. Physical competence (motor skill, fitness) interventions, rather than motivation or education, are needed for these youth.

Neighbourhood maternal socioeconomic status indicators and risk of congenital heart disease.

BACKGROUND: This study aimed to examine the relationships between various maternal socioeconomic status (SES) indicators and the risk of congenital heart disease (CHD). METHODS: This was a population-based retrospective cohort study, including all singleton stillbirths and live births in Ontario hospitals from April 1, 2012 to March 31, 2018. Multivariable logistic regression models were performed to examine the relationships between maternal neighbourhood household income, poverty, education level, employment and unemployment status, immigration and minority status, and population density and the risk of CHD. All SES variables were estimated at a dissemination area level and categorized into quintiles. Adjustments were made for maternal age at birth, assisted reproductive technology, obesity, pre-existing maternal health conditions, substance use during pregnancy, rural or urban residence, and infant's sex. RESULTS: Of 804,292 singletons, 9731 (1.21%) infants with CHD were identified. Compared to infants whose mothers lived in the highest income neighbourhoods, infants whose mothers lived in the lowest income neighbourhoods had higher likelihood of developing CHD (adjusted OR: 1.29, 95% CI: 1.20-1.38). Compared to infants whose mothers lived in the neighbourhoods with the highest percentage of people with a university or higher degree, infants whose mothers lived in the neighbourhoods with the lowest percentage of people with university or higher degree had higher chance of CHD (adjusted OR: 1.34, 95% CI: 1.24-1.44). Compared to infants whose mothers lived in the neighbourhoods with the highest employment rate, the odds of infants whose mothers resided in areas with the lowest employment having CHD was 18% higher (adjusted OR: 1.18, 95% CI: 1.10-1.26). Compared to infants whose mothers lived in the neighbourhoods with the lowest proportion of immigrants or minorities, infants whose mothers resided in areas with the highest proportions of immigrants or minorities had 18% lower odds (adjusted OR: 0.82, 95% CI: 0.77-0.88) and 16% lower odds (adjusted OR: 0.84, 95% CI: 0.78-0.91) of CHD, respectively. CONCLUSION: Lower maternal neighbourhood household income, poverty, lower educational level and unemployment status had positive associations with CHD, highlighting a significant social inequity in Ontario. The findings of lower CHD risk in immigrant and minority neighbourhoods require further investigation.

Prevention of post-cardiac surgery vitamin D deficiency in children with congenital heart disease: a pilot feasibility dose evaluation randomized controlled trial.

BACKGROUND: The vast majority of children undergoing cardiac surgery have low vitamin D levels post-operative, which may contribute to greater illness severity and worse clinical outcomes. Prior to the initiation of a large phase III clinical trial focused on clinical outcomes, studies are required to evaluate the feasibility of the study protocol, including whether the proposed dosing regimen can safely prevent post-operative vitamin D deficiency in this high-risk population. METHODS: We conducted a two-arm, double-blind dose evaluation randomized controlled trial in children requiring cardiopulmonary bypass for congenital heart disease. Pre-operatively, participants were randomized to receive cholecalciferol representing usual care (< 1 year = 400 IU/day, > 1 year = 600 IU/day) or a higher dose approximating the Institute of Medicine tolerable upper intake level (< 1 year = 1600 IU/day, > 1 year = 2400 IU/day). The feasibility outcomes were post-operative vitamin D status (primary), vitamin D-related adverse events, accrual rate, study withdrawal rate, blinding, and protocol non-adherence. RESULTS: Forty-six children were randomized, and five withdrew prior to surgery, leaving 41 children (21 high dose, 20 usual care) in the final analysis. The high dose group had higher 25-hydroxyvitamin D concentrations both intraoperatively (mean difference + 25.9 nmol/L; 95% CI 8.3-43.5) and post-operatively (mean difference + 17.2 nmol/L; 95% CI 5.5-29.0). Fewer participants receiving high-dose supplementation had post-operative serum 25-hydroxyvitamin D concentrations under 50 nmol/L, compared with usual care (RR 0.31, 95% CI 0.11-0.87). Post-operative vitamin D status was associated with the treatment arm and the number of doses received. There were no cases of hypercalcemia, and no significant adverse events related to vitamin D. While only 75% of the target sample size was recruited (limited funding), the consent rate (83%), accrual rate (1.5 per site month), number of withdrawals (11%), and ability to maintain blinding support feasibility of a larger trial. CONCLUSIONS: Pre-operative daily high-dose supplementation improved vitamin D status pre-operatively and at time of pediatric ICU admission. The protocol for a more definitive trial should limit enrollment of children with at least 30 days between randomization and surgery to allow adequate duration of supplementation or consider a loading dose. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01838447. Registered on April 24, 2013.

Prenatal Diagnosis of Transposition of the Great Arteries Reduces Postnatal Mortality: A Population-Based Study.

BACKGROUND: Transposition of the great arteries (TGA) may present as a life-threatening neonatal malformation. Although prenatal detection facilitates the perinatal management, the impact on outcome is controversial. METHODS: This study reviewed the differences in prenatal diagnosis of TGA from 2009 to 2014 among the 5 geographic areas in Ontario and compared the management, morbidity, and mortality among neonates with a prenatal (prenatal cohort; n = 70) vs a postnatal (postnatal cohort; n = 76) anomaly diagnosis. Cases were identified from prospective databases of the provincial cardiac tertiary centres and the coroner's office. RESULTS: Prenatal TGA detection rates varied significantly among areas (median: 50%; range: 14% to 72%; P = 0.03). Compared with the postnatal cohort, time from birth to tertiary care admission (1.4 vs 10.4 hours, P < 0.001), prostaglandin therapy (0.1 vs 5.3 hours; P < 0.001), balloon atrial septostomy (5.3 vs 14.9 hours; P <0.001), and arterial switch operation (6 vs 9 days, P = 0.002) was significantly shorter in the prenatal cohort. Although other preoperative variables-including the need of ventilation and mechanical support, morbidity score, and lowest pH and preductal oxygen saturations-were comparable, a prenatal diagnosis was associated with improved 1-year survival (odds ratio: 0.108; 95% confidence interval, 0.013-0.88; P = 0.0184). CONCLUSIONS: Prenatal diagnosis of TGA significantly shortened time intervals from birth to neonatal care and surgery and was associated with improved survival. The prenatal detection rate of TGA in Ontario was low (50% or less) outside of Metropolitan Toronto, suggesting the need for new strategies to further improve intraprovincial detection rates.

Impacting child health outcomes in congenital heart disease: Cluster randomized controlled trial protocol of in-clinic physical activity counselling.

BACKGROUND: Most (>90%) children with congenital health defects are not active enough for optimal health. Proactively promoting physical activity during every clinic visit is recommended, but rarely implemented due to a lack of appropriate resources. METHODS: This cluster randomized controlled trial will implement an evidence-based, multi-faceted physical activity intervention. All eligible patients at small (London, ON), medium (Ottawa, ON) and large (Edmonton, AB) pediatric cardiac clinics will be approached, with randomization to intervention/control by clinic and week. Intervention patients will be counselled with 5 key physical activity messages, have questions about physical activity answered, and have access to a custom web site with personalized activity suggestions and support from a Registered Kinesiologist. The primary outcome is daily physical activity (number of steps, minutes of moderate-to-vigorous activity) assessed via pedometer one week per month for 6-months. Standardized questionnaires assess activity motivation and quality of life at baseline and end of study. Healthcare outcomes will be clinic visit time and contacts for physical activity concerns. Repeated measures ANCOVA will compare control/intervention pedometer outcomes, adjusting for covariates (alpha=0.05). CONCLUSIONS: This trial aims to determine whether providing resources and protocols enables clinicians to counsel about physical activity as part of every pediatric cardiology appointment. Evaluations of healthcare system impact and intervention delivery in small, medium and large clinics will assess applicability for implementation in all pediatric cardiac clinics. The impact on physical activity motivation and participation will evaluate the effectiveness of this standardized approach for increasing physical activity in children with congenital heart defects.

Associations of Assisted Reproductive Technology and Twin Pregnancy With Risk of Congenital Heart Defects.

Importance: The extent to which assisted reproductive technology is associated with increased risk of congenital heart defects independent of its known association with twinning remains uncertain. Objective: To assess the extent to which assisted pregnancy is associated with increased risk of congenital heart defects independent of its known association with twinning. Design, Setting, and Participants: This retrospective cohort study linked records of congenital heart defect diagnoses with assisted reproductive technology cycles in 507 390 singleton or twin pregnancies (10 149 assisted pregnancies and 497 241 nonassisted pregnancies), including singleton and twin early pregnancy losses, stillbirths, and live births (follow-up to 1 year of age) in Ontario, Canada, between April 1, 2012, and October 31, 2015. Statistical analysis was performed from January 1, 2017, to September 9, 2019. Exposures: Assisted reproductive technology and its 2 subtypes: intracytoplasmic sperm injection and in vitro fertilization without intracytoplasmic sperm injection. Main Outcomes and Measures: The main outcome was congenital heart defects (prevalence and relative risk measured as odds ratios [ORs]). Mediation analysis was performed to assess the extent to which the association between assisted reproductive technology and congenital heart defects was mediated by twinning. Results: Of 507 390 mother-infant pairs with singleton or twin pregnancies evaluated, the prevalence of congenital heart defects in assisted pregnancies (223 [2.2%]) was higher than that in nonassisted pregnancies (6057 [1.2%]; crude OR, 1.82; 95% CI, 1.59-2.09). The strength of the association between assisted pregnancy and congenital heart defects decreased after adjusting for several risk factors simultaneously (adjusted OR, 1.70; 95% CI, 1.48-1.95). Further mediation analysis indicated that most of the association between assisted pregnancy and congenital heart defects was mediated by twinning (adjusted OR, 1.68; 95% CI, 1.44-1.92), and the natural direct association of assisted pregnancy with congenital heart defects among singleton pregnancies was 1.09 (95% CI, 0.93-1.25). Mediation of twinning accounted for 87.3% of the association. Conclusions and Relevance: Our study results suggest that the association between assisted reproductive technology and congenital heart defects may be mediated by twinning.

"I really like playing games together": Understanding what influences children with congenital heart disease to participate in physical activity.

BACKGROUND: Participation in physical activity is essential to the long-term health and development of all children. However, children living with cardiac conditions are typically not active enough to sustain positive health outcomes. Understanding the experiences of children living with congenital heart disease in community-based settings could help inform the physical activity counselling practices of clinicians. The current study explored the perceptions of 7- to 10-year-old children with moderate or complex congenital heart disease as they participated in a 10-week multisport programme. METHODS: Detailed field notes recorded the discussions and behaviours of 11 participants (45% female participants) each week during the programme sessions. Among those, four participants (50% female participants) were purposively selected to participate in preprogramme and postprogramme focus groups to gather more detailed accounts of their experiences. RESULTS: Four main themes surrounding physical activity were identified: (a) motivation, (b) self-efficacy, (c) peer influences, and (d) family influences. Although feelings of excitement and enjoyment towards physical activity were prevalent throughout the data ("I'm really excited … because I really like those sports"), participants also often felt frustrated, nervous, and fatigued ("I'm not very good at the skills"). Social inclusion with peers and family influences were meaningful reasons to engage in physical activity ("I really like playing games together"). Following the completion of the programme, participants emphasized their enjoyment of physical activity as a primary source of motivation, demonstrating an important shift from recognizing positive health outcomes ( "… it's good for you") towards more intrinsic sources of motivation ("… because it's fun"). CONCLUSION: Opportunities for physical activity that enhance positive experiences and build intrinsic motivation should be identified and promoted to children with congenital heart disease. Community-based programmes may also be an appropriate context for children with cardiac conditions to engage and maintain participation in physical activity through adolescence.

Machine Learning Identifies Clinical and Genetic Factors Associated With Anthracycline Cardiotoxicity in Pediatric Cancer Survivors.

BACKGROUND: Despite known clinical risk factors, predicting anthracycline cardiotoxicity remains challenging. OBJECTIVES: This study sought to develop a clinical and genetic risk prediction model for anthracycline cardiotoxicity in childhood cancer survivors. METHODS: We performed exome sequencing in 289 childhood cancer survivors at least 3 years from anthracycline exposure. In a nested case-control design, 183 case patients with reduced left ventricular ejection fraction despite low-dose doxorubicin (≤250 mg/m2), and 106 control patients with preserved left ventricular ejection fraction despite doxorubicin >250 mg/m2 were selected as extreme phenotypes. Rare/low-frequency variants were collapsed to identify genes differentially enriched for variants between case patients and control patients. The expression levels of 5 top-ranked genes were evaluated in human induced pluripotent stem cell-derived cardiomyocytes, and variant enrichment was confirmed in a replication cohort. Using random forest, a risk prediction model that included genetic and clinical predictors was developed. RESULTS: Thirty-one genes were differentially enriched for variants between case patients and control patients (p < 0.001). Only 42.6% case patients harbored a variant in these genes compared to 89.6% control patients (odds ratio: 0.09; 95% confidence interval: 0.04 to 0.17; p = 3.98 × 10-15). A risk prediction model for cardiotoxicity that included clinical and genetic factors had a higher prediction accuracy and lower misclassification rate compared to the clinical-only model. In vitro inhibition of gene-associated pathways (PI3KR2, ZNF827) provided protection from cardiotoxicity in cardiomyocytes. CONCLUSIONS: Our study identified variants in cardiac injury pathway genes that protect against cardiotoxicity and informed the development of a prediction model for delayed anthracycline cardiotoxicity, and it also provided new targets in autophagy genes for the development of cardio-protective drugs. (Preventing Cardiac Sequelae in Pediatric Cancer Survivors [PCS2]; NCT01805778).

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.