Contemporary Trends in Cardiac Surgical Care for Trisomy 13 and 18 Patients Admitted to Hospitals in the United States.

OBJECTIVE: To assess rates of cardiac surgery and the clinical and demographic features that influence surgical vs nonsurgical treatment of congenital heart disease (CHD) in patients with trisomy 13 (T13) and trisomy 18 (T18) in the United States. STUDY DESIGN: A retrospective study was performed using the Pediatric Health Information System. All hospital admissions of children (<18 years of age) with T13 and T18 in the United States were identified from 2003 through 2022. International Classifications of Disease (ICD) codes were used to identify presence of CHD, extracardiac comorbidities/malformations, and performance of cardiac surgery. RESULTS: Seven thousand one hundred thirteen patients were identified. CHD was present in 62% (1625/2610) of patients with T13 and 73% (3288/4503) of patients with T18. The most common CHD morphologies were isolated atrial/ventricular septal defects (T13 40%, T18 42%) and aortic hypoplasia/coarctation (T13 21%, T18 23%). Single-ventricle morphologies comprised 6% (100/1625) of the T13 and 5% (167/3288) of the T18 CHD cohorts. Surgery was performed in 12% of patients with T13 plus CHD and 17% of patients with T18 plus CHD. For all cardiac diagnoses, <50% of patients received surgery. Nonsurgical patients were more likely to be born prematurely (P < .05 for T13 and T18). The number of extracardiac comorbidities was similar between surgical/nonsurgical patients with T13 (median 2 vs 2, P = .215) and greater in surgical vs nonsurgical patients with T18 (median 3 vs 2, P < .001). Hospital mortality was <10% for both surgical cohorts. CONCLUSIONS: Patients with T13 or T18 and CHD receive surgical palliation, but at a low prevalence (≤17%) nationally. Given operative mortality <10%, opportunity exists perhaps for quality improvement in the performance of cardiac surgery for these vulnerable patient populations.

Wellbeing in Children and Adolescents with Fontan Physiology.

OBJECTIVE: To assess health-related quality of life (HRQOL) and global quality of life (QOL) in children and adolescents with Fontan physiology and identify key predictors influencing these outcomes. STUDY DESIGN: Cross-sectional analysis of 73 children and adolescents enrolled in the Australia and New Zealand Fontan Registry aged 6-17 years, at least 12 months post-Fontan operation. Assessments included the Pediatric Quality of Life Inventory (PedsQL) for HRQOL and a developmentally-tailored visual analogue scale (0-10) for global QOL, along with validated sociodemographic, clinical, psychological, relational, and parental measures. Clinical data were provided by the Australia and New Zealand Fontan Registry. RESULTS: Participants (mean age: 11.5 ± 2.6 years, 62% male) reported lower overall HRQOL (P < .001), and lower scores across all HRQOL domains (all P < .0001), compared with normative data. Median global QOL score was 7.0 (IQR 5.8-8.0), with most participants (79%) rating their global QOL ≥6. Anxiety and depressive symptoms requiring clinical assessment were reported by 21% and 26% of participants, respectively. Age, sex, and perceived seriousness of congenital heart disease explained 15% of the variation in HRQOL scores, while depressive symptoms and treatment-related anxiety explained an additional 37% (final model: 52% of variance explained). For global QOL, sociodemographic and clinical factors explained 13% of the variance in scores, while depressive symptoms explained a further 25% (final model: 38% of variance explained). Parental factors were not associated with child QOL outcomes. CONCLUSIONS: Children and adolescents with Fontan physiology experience lower HRQOL than community-based norms, despite reporting fair overall QOL. Psychological factors predominantly influenced QOL outcomes, indicating strategies to bolster psychological health could improve QOL in this population.

Persistent acute kidney injury and fluid accumulation with outcomes after the Norwood procedure: report from NEPHRON.

BACKGROUND: Cardiac surgery-associated acute kidney injury (CS-AKI) is common, but its impact on clinical outcomes is variable. Parsing AKI into sub-phenotype(s) and integrating pathologic positive cumulative fluid balance (CFB) may better inform prognosis. We sought to determine whether durational sub-phenotyping of CS-AKI with CFB strengthens association with outcomes among neonates undergoing the Norwood procedure. METHODS: Multicenter, retrospective cohort study from the Neonatal and Pediatric Heart and Renal Outcomes Network. Transient CS-AKI: present only on post-operative day (POD) 1 and/or 2; persistent CS-AKI: continued after POD 2. CFB was evaluated per day and peak CFB during the first 7 postoperative days. Primary and secondary outcomes were mortality, respiratory support-free and hospital-free days (at 28, 60 days, respectively). The primary predictor was persistent CS-AKI, defined by modified neonatal Kidney Disease: Improving Global Outcomes criteria. RESULTS: CS-AKI occurred in 59% (205/347) neonates: 36.6% (127/347) transient and 22.5% (78/347) persistent; CFB > 10% occurred in 18.7% (65/347). Patients with either persistent CS-AKI or peak CFB > 10% had higher mortality. Combined persistent CS-AKI with peak CFB > 10% (n = 21) associated with increased mortality (aOR: 7.8, 95% CI: 1.4, 45.5; p = 0.02), decreased respiratory support-free (predicted mean 12 vs. 19; p < 0.001) and hospital-free days (17 vs. 29; p = 0.048) compared to those with neither. CONCLUSIONS: The combination of persistent CS-AKI and peak CFB > 10% after the Norwood procedure is associated with mortality and hospital resource utilization. Prospective studies targeting intra- and postoperative CS-AKI risk factors and reducing CFB have the potential to improve outcomes.

Mother-Infant Dyadic Synchrony and Interaction Patterns After Infant Cardiac Surgery.

OBJECTIVE: Parents and their infants with complex congenital heart disease (CHD) face relational challenges, including marked distress, early separations, and infant hospitalizations and medical procedures, yet the prevalence of parent-infant interaction difficulties remains unclear. Using a standardized observational paradigm, this study investigated mother-infant dyadic synchrony, interactional patterns, and associated predictors in mother-infant pairs affected by CHD, compared with typically-developing pairs. METHODS: In this prospective, longitudinal cohort study, mothers and their infants requiring cardiac surgery before age 6-months (n=110 pairs) and an age- and sex-matched Australian community sample (n=85 pairs) participated in a filmed, free-play interaction at 6.9±1.0 months. Mother-infant dyadic synchrony, maternal and infant interactional patterns, and relational risk were assessed using the Child-Adult Relationship Experimental (CARE) Index. Maternal and infant predictors were assessed at 32 weeks gestation, 3- and 6-months postpartum. RESULTS: Most mother-infant interactions were classified as "high risk" or "inept" (cardiac: 94%, control: 81%; p=.007). Dyadic synchrony (p<.001), maternal sensitivity (p=.001), and infant cooperativeness (p=.001) were lower for cardiac than control pairs. Higher maternal traumatic stress at 6-months postpartum predicted lower dyadic synchrony for mother-infant pairs affected by CHD (B=-.04, p=.03). Dyadic synchrony was higher among older infants in the total (B=.40, p=.003) but not cardiac sample (B=.24, p=.06). CONCLUSIONS: Relational difficulties were almost universal among mother-infant pairs affected by CHD and were also high in the Australian community sample. Widespread education initiatives are recommended to increase awareness of heightened mother-infant relational risk in congenital heart care and well-child settings, alongside relationally-focused prevention and early intervention programs.

Phenotypes and genotypes in a cohort of children with single-ventricle CHD.

OBJECTIVE: CHD is known to be associated with increased risk for neurodevelopmental disorders. The combination of CHD with neurodevelopmental disorders and/or extra-cardiac anomalies increases the chance for an underlying genetic diagnosis. Over the last 15 years, there has been a dramatic increase in the use of broad-scale genetic testing. We sought to determine if neurodevelopmental disorders in children with single-ventricle CHD born prior to the genetic testing revolution are associated with genetic diagnosis. METHODS: We identified 74 5-12-year-old patients with single-ventricle CHD post-Fontan procedure. We retrospectively evaluated genetic testing performed and neurodevelopmental status of these patients. RESULTS: In this cohort, there was an overall higher rate of neurodevelopmental disorders (80%) compared to the literature (50%). More of the younger (5-7-year-old) patients were seen by genetic counsellors compared to the older (8-12-year-old) cohort (46% versus 19% p value = 0.01). In the younger cohort, the average age of initial consultation was 7.7 days compared to 251 days in the older cohort. The overall rate of achieving a molecular diagnosis was 12% and 8% in the younger and older cohorts, respectively; however, the vast majority of did not have broad genetic testing. CONCLUSION: The minority of patients in our cohort achieved a genetic diagnosis. Given a large increase in the number of genes associated with monogenic CHD and neurodevelopmental disorders in the last decade, comprehensive testing and consultation with clinical genetics should be considered in this age range, since current testing standards did not exist during their infancy.

ConanVarvar: a versatile tool for the detection of large syndromic copy number variation from whole-genome sequencing data.

BACKGROUND: A wide range of tools are available for the detection of copy number variants (CNVs) from whole-genome sequencing (WGS) data. However, none of them focus on clinically-relevant CNVs, such as those that are associated with known genetic syndromes. Such variants are often large in size, typically 1-5 Mb, but currently available CNV callers have been developed and benchmarked for the discovery of smaller variants. Thus, the ability of these programs to detect tens of real syndromic CNVs remains largely unknown. RESULTS: Here we present ConanVarvar, a tool which implements a complete workflow for the targeted analysis of large germline CNVs from WGS data. ConanVarvar comes with an intuitive R Shiny graphical user interface and annotates identified variants with information about 56 associated syndromic conditions. We benchmarked ConanVarvar and four other programs on a dataset containing real and simulated syndromic CNVs larger than 1 Mb. In comparison to other tools, ConanVarvar reports 10-30 times less false-positive variants without compromising sensitivity and is quicker to run, especially on large batches of samples. CONCLUSIONS: ConanVarvar is a useful instrument for primary analysis in disease sequencing studies, where large CNVs could be the cause of disease.

Not all durations of preheart transplant mechanical ventilation portend inferior post-transplant survival in children.

BACKGROUND: Mechanical ventilation prior to pediatric heart transplantation predicts inferior post-transplant survival, but the impact of ventilation duration on survival is unclear. METHODS: Data from the United Network for Organ Sharing and Pediatric Health Information System were used to identify pediatric (<18 years) heart transplant recipients from 2003 to 2020. Patients ventilated pretransplant were first compared to no ventilation, then ventilation durations were compared across quartiles of ventilation (≤1 week, 8 days-5 weeks, >5 weeks). RESULTS: At transplant, 11% (511/4506) of patients required ventilation. Ventilated patients were younger, had more congenital heart disease, more urgent listing-status, and greater rates of nephropathy, TPN-dependence, and inotrope and ECMO requirements (p < .001 for all). Post-transplant, previously ventilated patients experienced longer ventilation durations, ICU and hospital stays, and inferior survival (all p < .001). Hospital outcomes and survival worsened with longer pretransplant ventilation. One-year and overall survival were similar between the no-ventilation and ≤1 week groups (p = .703 & p = .433, respectively) but were significantly worse for ventilation durations >1 week (p < .001). On multivariable analysis, ventilation ≤1 week did not predict mortality (HR 0.98 [95% CI 0.85-1.43]), whereas ventilation >1 week did (HR: 1.18 [1.01-1.39]). CONCLUSIONS: Longer pretransplant ventilation portends worse outcomes, although only ventilation >1 week predicts mortality. These findings can inform pretransplant prognostication.

Neurocognitive Dysfunction and Smaller Brain Volumes in Adolescents and Adults With a Fontan Circulation.

BACKGROUND: Neurocognitive outcomes beyond childhood in people with a Fontan circulation are not well defined. This study aimed to investigate neurocognitive functioning in adolescents and adults with a Fontan circulation and associations with structural brain injury, brain volumetry, and postnatal clinical factors. METHODS: In a binational study, participants with a Fontan circulation without a preexisting major neurological disability were prospectively recruited from the Australia and New Zealand Fontan Registry. Neurocognitive function was assessed by using Cogstate software in 107 participants with a Fontan circulation and compared with control groups with transposition of the great arteries (n=50) and a normal circulation (n=41). Brain MRI with volumetric analysis was performed in the participants with a Fontan circulation and compared with healthy control data from the ABIDE I and II (Autism Brain Imaging Data Exchange) and PING (Pediatric Imaging, Neurocognition, and Genetics) data repositories. Clinical data were retrospectively collected. RESULTS: Of the participants with a Fontan circulation who had a neurocognitive assessment, 55% were male and the mean age was 22.6 years (SD 7.8). Participants with a Fontan circulation performed worse in several areas of neurocognitive function compared with those with transposition of the great arteries and healthy controls (P<0.05). Clinical factors associated with worse neurocognitive outcomes included more inpatient days during childhood, younger age at Fontan surgery, and longer time since Fontan procedure (P<0.05). Adults with a Fontan circulation had more marked neurocognitive dysfunction than adolescents with a Fontan circulation in 2 domains (psychomotor function, P=0.01 and working memory, P=0.02). Structural brain injury was present in the entire Fontan cohort; the presence of white matter injury was associated with worse paired associate learning (P<0.001), but neither the presence nor severity of infarct, subcortical gray matter injury, and microhemorrhage was associated with neurocognitive outcomes. Compared with healthy controls, people with a Fontan circulation had smaller global brain volumes (P<0.001 in all regions) and smaller regional brain volumes in most cerebral cortical regions (P<0.05). Smaller global brain volumes were associated with worse neurocognitive functioning in several domains (P<0.05). A significant positive association was also identified between global brain volumes and resting oxygen saturations (P≤0.04). CONCLUSIONS: Neurocognitive impairment is common in adolescents and adults with a Fontan circulation and is associated with smaller gray and white matter brain volume. Understanding modifiable factors that contribute to brain injury to optimize neurocognitive function is paramount.

Functional genomics and gene-environment interaction highlight the complexity of congenital heart disease caused by Notch pathway variants.

Congenital heart disease (CHD) is the most common birth defect and brings with it significant mortality and morbidity. The application of exome and genome sequencing has greatly improved the rate of genetic diagnosis for CHD but the cause in the majority of cases remains uncertain. It is clear that genetics, as well as environmental influences, play roles in the aetiology of CHD. Here we address both these aspects of causation with respect to the Notch signalling pathway. In our CHD cohort, variants in core Notch pathway genes account for 20% of those that cause disease, a rate that did not increase with the inclusion of genes of the broader Notch pathway and its regulators. This is reinforced by case-control burden analysis where variants in Notch pathway genes are enriched in CHD patients. This enrichment is due to variation in NOTCH1. Functional analysis of some novel missense NOTCH1 and DLL4 variants in cultured cells demonstrate reduced signalling activity, allowing variant reclassification. Although loss-of-function variants in DLL4 are known to cause Adams-Oliver syndrome, this is the first report of a hypomorphic DLL4 allele as a cause of isolated CHD. Finally, we demonstrate a gene-environment interaction in mouse embryos between Notch1 heterozygosity and low oxygen- or anti-arrhythmic drug-induced gestational hypoxia, resulting in an increased incidence of heart defects. This implies that exposure to environmental insults such as hypoxia could explain variable expressivity and penetrance of observed CHD in families carrying Notch pathway variants.

Insights into the genetic architecture underlying complex, critical congenital heart disease.

Congenital heart disease (CHD) has a multifactorial aetiology, raising the possibility of an underlying genetic burden, predisposing to disease but also variable expression, including variation in disease severity, and incomplete penetrance. Using whole genome sequencing (WGS), the findings of this study, indicate that complex, critical CHD is distinct from other types of disease due to increased genetic burden in common variation, specifically among established CHD genes. Additionally, these findings highlight associations with regulatory genes and environmental "stressors" in the final presentation of disease.

Whole genome sequencing in transposition of the great arteries and associations with clinically relevant heart, brain and laterality genes.

BACKGROUND: The most common cyanotic congenital heart disease (CHD) requiring management as a neonate is transposition of great arteries (TGA). Clinically, up to 50% of TGA patients develop some form of neurodevelopmental disability (NDD), thought to have a significant genetic component. A "ciliopathy" and links with laterality disorders have been proposed. This first report of whole genome sequencing in TGA, sought to identify clinically relevant variants contributing to heart, brain and laterality defects. METHODS: Initial whole genome sequencing analyses on 100 TGA patients focussed on established disease genes related to CHD (n = 107), NDD (n = 659) and heterotaxy (n = 74). Single variant as well as copy number variant analyses were conducted. Variant pathogenicity was assessed using the American College of Medical Genetics and Genomics-Association for Molecular Pathology guidelines. RESULTS: Fifty-five putatively damaging variants were identified in established disease genes associated with CHD, NDD and heterotaxy; however, no clinically relevant variants could be attributed to disease. Notably, case-control analyses identified significantly more predicted-damaging, silent and total variants in TGA cases than healthy controls in established CHD genes (P < .001), NDD genes (P < .001) as well as across the three gene panels (P < .001). CONCLUSION: We present compelling evidence that the majority of TGA is not caused by monogenic rare variants and is most likely oligogenic and/or polygenic in nature, highlighting the complex genetic architecture and multifactorial influences on this CHD sub-type and its long-term sequelae. Assessment of variant burden in key heart, brain and/or laterality genes may be required to unravel the genetic contributions to TGA and related disabilities.

Effect of Nitric Oxide via Cardiopulmonary Bypass on Ventilator-Free Days in Young Children Undergoing Congenital Heart Disease Surgery: The NITRIC Randomized Clinical Trial.

Importance: In children undergoing heart surgery, nitric oxide administered into the gas flow of the cardiopulmonary bypass oxygenator may reduce postoperative low cardiac output syndrome, leading to improved recovery and shorter duration of respiratory support. It remains uncertain whether nitric oxide administered into the cardiopulmonary bypass oxygenator improves ventilator-free days (days alive and free from mechanical ventilation). Objective: To determine the effect of nitric oxide applied into the cardiopulmonary bypass oxygenator vs standard care on ventilator-free days in children undergoing surgery for congenital heart disease. Design, Setting, and Participants: Double-blind, multicenter, randomized clinical trial in 6 pediatric cardiac surgical centers in Australia, New Zealand, and the Netherlands. A total of 1371 children younger than 2 years undergoing congenital heart surgery were randomized between July 2017 and April 2021, with 28-day follow-up of the last participant completed on May 24, 2021. Interventions: Patients were assigned to receive nitric oxide at 20 ppm delivered into the cardiopulmonary bypass oxygenator (n = 679) or standard care cardiopulmonary bypass without nitric oxide (n = 685). Main Outcomes and Measures: The primary end point was the number of ventilator-free days from commencement of bypass until day 28. There were 4 secondary end points including a composite of low cardiac output syndrome, extracorporeal life support, or death; length of stay in the intensive care unit; length of stay in the hospital; and postoperative troponin levels. Results: Among 1371 patients who were randomized (mean [SD] age, 21.2 [23.5] weeks; 587 girls [42.8%]), 1364 (99.5%) completed the trial. The number of ventilator-free days did not differ significantly between the nitric oxide and standard care groups, with a median of 26.6 days (IQR, 24.4 to 27.4) vs 26.4 days (IQR, 24.0 to 27.2), respectively, for an absolute difference of -0.01 days (95% CI, -0.25 to 0.22; P = .92). A total of 22.5% of the nitric oxide group and 20.9% of the standard care group developed low cardiac output syndrome within 48 hours, needed extracorporeal support within 48 hours, or died by day 28, for an adjusted odds ratio of 1.12 (95% CI, 0.85 to 1.47). Other secondary outcomes were not significantly different between the groups. Conclusions and Relevance: In children younger than 2 years undergoing cardiopulmonary bypass surgery for congenital heart disease, the use of nitric oxide via cardiopulmonary bypass did not significantly affect the number of ventilator-free days. These findings do not support the use of nitric oxide delivered into the cardiopulmonary bypass oxygenator during heart surgery. Trial Registration: anzctr.org.au Identifier: ACTRN12617000821392.

Whole Exome Sequencing Reveals the Major Genetic Contributors to Nonsyndromic Tetralogy of Fallot.

RATIONALE: Familial recurrence studies provide strong evidence for a genetic component to the predisposition to sporadic, nonsyndromic Tetralogy of Fallot (TOF), the most common cyanotic congenital heart disease phenotype. Rare genetic variants have been identified as important contributors to the risk of congenital heart disease, but relatively small numbers of TOF cases have been studied to date. OBJECTIVE: We used whole exome sequencing to assess the prevalence of unique, deleterious variants in the largest cohort of nonsyndromic TOF patients reported to date. METHODS AND RESULTS: Eight hundred twenty-nine TOF patients underwent whole exome sequencing. The presence of unique, deleterious variants was determined; defined by their absence in the Genome Aggregation Database and a scaled combined annotation-dependent depletion score of ≥20. The clustering of variants in 2 genes, NOTCH1 and FLT4, surpassed thresholds for genome-wide significance (assigned as P<5×10-8) after correction for multiple comparisons. NOTCH1 was most frequently found to harbor unique, deleterious variants. Thirty-one changes were observed in 37 probands (4.5%; 95% CI, 3.2%-6.1%) and included 7 loss-of-function variants 22 missense variants and 2 in-frame indels. Sanger sequencing of the unaffected parents of 7 cases identified 5 de novo variants. Three NOTCH1 variants (p.G200R, p.C607Y, and p.N1875S) were subjected to functional evaluation, and 2 showed a reduction in Jagged1-induced NOTCH signaling. FLT4 variants were found in 2.4% (95% CI, 1.6%-3.8%) of TOF patients, with 21 patients harboring 22 unique, deleterious variants. The variants identified were distinct to those that cause the congenital lymphoedema syndrome Milroy disease. In addition to NOTCH1, FLT4 and the well-established TOF gene, TBX1, we identified potential association with variants in several other candidates, including RYR1, ZFPM1, CAMTA2, DLX6, and PCM1. CONCLUSIONS: The NOTCH1 locus is the most frequent site of genetic variants predisposing to nonsyndromic TOF, followed by FLT4. Together, variants in these genes are found in almost 7% of TOF patients.

Selective serotonin reuptake inhibitor or serotonin-norepinephrine reuptake inhibitors and epidemiological characteristics associated with prenatal diagnosis of congenital heart disease.

OBJECTIVE: Identify early pregnancy associations of congenital heart disease (CHD) in a multiethnic cohort. METHODS: This retrospective observational cohort study compared the general obstetric population to women who gave birth at a referral centre in Australia between 2012 and 2017, after 20 weeks' of gestation, with a pregnancy affected by CHD. We defined mood disorder and anxiety as a history of self-reported or medically diagnosed anxiety, depression, postpartum depression or bipolar disorder. RESULTS: We compared epidemiological factors between 30 842 general obstetric patients and 470 obstetric patients with a foetus affected by CHD. Multivariate analysis showed independent associations between CHD and use of selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs) in the first trimester (relative risk [RR] 4.14, 95% CI 2.58-6.65), history of anxiety or mood disorder with no SSRI/SNRI first trimester (RR 2.20, 95% CI 1.77-2.74), folate and/or pregnancy multivitamin use in the first trimester (RR 0.69, 95% CI 0.55-0.87) and increased risk with maternal age >40 years (RR 2.30, 95% CI 1.57-3.38). CONCLUSIONS: Our data show maternal mood disorders with and without SSRI or SNRI use, maternal age >40 years and lack of multivitamin/folate use to be independently associated with CHD in pregnancy.

Debate - Replacement of the Mitral Valve Under One Year of Age: Mechanical Valves Should Be Used.

This article reviews the literature, focusing on publications from the third millennium and the results of mitral valve replacement in children younger than 1 year of age. Special consideration has been given to neonatal and infant valve replacement to provide insights into valve choice and technique. Mitral valve replacement is an important topic because it carries the highest mortality and poorer long-term prognosis than any other valve replacement in children.

NAD Deficiency, Congenital Malformations, and Niacin Supplementation.

BACKGROUND: Congenital malformations can be manifested as combinations of phenotypes that co-occur more often than expected by chance. In many such cases, it has proved difficult to identify a genetic cause. We sought the genetic cause of cardiac, vertebral, and renal defects, among others, in unrelated patients. METHODS: We used genomic sequencing to identify potentially pathogenic gene variants in families in which a person had multiple congenital malformations. We tested the function of the variant by using assays of in vitro enzyme activity and by quantifying metabolites in patient plasma. We engineered mouse models with similar variants using the CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 system. RESULTS: Variants were identified in two genes that encode enzymes of the kynurenine pathway, 3-hydroxyanthranilic acid 3,4-dioxygenase (HAAO) and kynureninase (KYNU). Three patients carried homozygous variants predicting loss-of-function changes in the HAAO or KYNU proteins (HAAO p.D162*, HAAO p.W186*, or KYNU p.V57Efs*21). Another patient carried heterozygous KYNU variants (p.Y156* and p.F349Kfs*4). The mutant enzymes had greatly reduced activity in vitro. Nicotinamide adenine dinucleotide (NAD) is synthesized de novo from tryptophan through the kynurenine pathway. The patients had reduced levels of circulating NAD. Defects similar to those in the patients developed in the embryos of Haao-null or Kynu-null mice owing to NAD deficiency. In null mice, the prevention of NAD deficiency during gestation averted defects. CONCLUSIONS: Disruption of NAD synthesis caused a deficiency of NAD and congenital malformations in humans and mice. Niacin supplementation during gestation prevented the malformations in mice. (Funded by the National Health and Medical Research Council of Australia and others.).

"Why and how did this happen?": development and evaluation of an information resource for parents of children with CHD.

BACKGROUND: The causes of CHD are complex and often unknown, leading parents to ask how and why this has happened. Genetic counselling has been shown to benefit these parents by providing information and support; however, most parents currently do not receive this service. This study aimed to develop a brochure to determine whether an information resource could improve parents' knowledge about CHD causation and inheritance and increase psychosocial functioning. METHODS: In development, the resource was assessed against several readability scales and piloted. Parents of children attending preadmission clinic for surgery were included. Assessments occurred pre- and post-receiving the information resource using a purpose-designed knowledge measure and validated psychological measures. RESULTS: Participant's (n = 52) knowledge scores increased significantly from the pre-questionnaire ( ${\overline x}\, = \,5/10$ , sd = 2.086) to post-questionnaire ( $\overline x\, = \,7.88/10$ , sd = 2.094, p < 0.001), with all aware that CHD can be caused by genetic factors after reading the brochure. Perceived personal control also increased from pre- ( $\overline x\, = \,11.856/18$ , sd = 4.339) to post-brochure ( $\overline x\, = \,14.644/18$ , sd = 3.733, p < 0.001), and many reported reduced feelings of guilt. No negative emotional response to the brochure was reported. The information provided was considered relevant (88%), reassuring (86%), and 88% would recommend the brochure to other parents. However, some wanted more emotional support and assistance in what to tell their child. CONCLUSIONS: Use of the information resource significantly enhanced parents' knowledge of CHD causation and increased their psychosocial functioning. It is a valuable resource in the absence of genetic counselling; however, it should not replace formal genetic counselling when required.

De novo, deleterious sequence variants that alter the transcriptional activity of the homeoprotein PBX1 are associated with intellectual disability and pleiotropic developmental defects.

We present eight patients with de novo, deleterious sequence variants in the PBX1 gene. PBX1 encodes a three amino acid loop extension (TALE) homeodomain transcription factor that forms multimeric complexes with TALE and HOX proteins to regulate target gene transcription during development. As previously reported, Pbx1 homozygous mutant mice (Pbx1-/-) develop malformations and hypoplasia or aplasia of multiple organs, including the craniofacial skeleton, ear, branchial arches, heart, lungs, diaphragm, gut, kidneys, and gonads. Clinical findings similar to those in Pbx mutant mice were observed in all patients with varying expressivity and severity, including external ear anomalies, abnormal branchial arch derivatives, heart malformations, diaphragmatic hernia, renal hypoplasia and ambiguous genitalia. All patients but one had developmental delays. Previously reported patients with congenital anomalies affecting the kidney and urinary tract exhibited deletions and loss of function variants in PBX1. The sequence variants in our cases included missense substitutions adjacent to the PBX1 homeodomain (p.Arg184Pro, p.Met224Lys, and p.Arg227Pro) or within the homeodomain (p.Arg234Pro, and p.Arg235Gln), whereas p.Ser262Glnfs*2, and p.Arg288* yielded truncated PBX1 proteins. Functional studies on five PBX1 sequence variants revealed perturbation of intrinsic, PBX-dependent transactivation ability and altered nuclear translocation, suggesting abnormal interactions between mutant PBX1 proteins and wild-type TALE or HOX cofactors. It is likely that the mutations directly affect the transcription of PBX1 target genes to impact embryonic development. We conclude that deleterious sequence variants in PBX1 cause intellectual disability and pleiotropic malformations resembling those in Pbx1 mutant mice, arguing for strong conservation of gene function between these two species.

Identification of clinically actionable variants from genome sequencing of families with congenital heart disease.

PURPOSE: Congenital heart disease (CHD) affects up to 1% of live births. However, a genetic diagnosis is not made in most cases. The purpose of this study was to assess the outcomes of genome sequencing (GS) of a heterogeneous cohort of CHD patients. METHODS: Ninety-seven families with probands born with CHD requiring surgical correction were recruited for genome sequencing. At minimum, a proband-parents trio was sequenced per family. GS data were analyzed via a two-tiered method: application of a high-confidence gene screen (hcCHD), and comprehensive analysis. Identified variants were assessed for pathogenicity using the American College of Medical Genetics and Genomics-Association for Molecular Pathology (ACMG-AMP) guidelines. RESULTS: Clinically relevant genetic variants in known and emerging CHD genes were identified. The hcCHD screen identified a clinically actionable variant in 22% of families. Subsequent comprehensive analysis identified a clinically actionable variant in an additional 9% of families in genes with recent disease associations. Overall, this two-tiered approach provided a clinically relevant variant for 31% of families. CONCLUSIONS: Interrogating GS data using our two-tiered method allowed identification of variants with high clinical utility in a third of our heterogeneous cohort. However, association of emerging genes with CHD etiology, and development of novel technologies for variant assessment and interpretation, will increase diagnostic yield during future reassessment of our GS data.

Need for Routine Screening of Health-Related Quality of Life in Families of Young Children with Complex Congenital Heart Disease.

OBJECTIVES: To assess health-related quality of life (HRQOL) in families of young children with complex congenital heart disease (CHD), and identify the demographic, clinical, and psychosocial factors that place these children and their mothers at greater risk of vulnerability. STUDY DESIGN: This cross-sectional study took place from June 2015 to October 2016 at The Sydney Children's Hospitals Network Cardiac Service, Australia. Mothers of a child aged 1-5 years with either single ventricle CHD or CHD requiring neonatal biventricular repair were invited to participate. Eighty-seven mothers completed a suite of validated measures, including the Pediatric Quality of Life Inventory, which assessed the outcomes of child and maternal HRQOL. RESULTS: Sixty percent of children with single ventricle CHD and 25% of children with biventricular repair had total Pediatric Quality of Life Inventory scores within the at-risk range. Lower child HRQOL was strongly associated with single ventricle CHD (ß = -0.38; P < .001), physical comorbidity (ß = -0.32; P = .001), feeding difficulties (ß = -0.26; P = .008), and greater maternal psychological stress (ß = -0.18; P = .045), accounting for 52% of the variance in child HRQOL. Lower maternal HRQOL was strongly associated with poorer family functioning (ß = 0.61; P < .001), greater maternal psychological stress (ß = -0.23; P = .004), child physical comorbidity (ß = -0.17; P = .01), and a 'difficult' child temperament (ß = -0.14; P = .01), accounting for 73% of the variance in maternal HRQOL. CONCLUSIONS: Lower HRQOL is common in young children with complex CHD, particularly single ventricle CHD. Several predictors of HRQOL are potentially modifiable, offering possible pathways for prevention and early intervention. Routine screening is a necessary first step toward developing models of care to improve HRQOL in this population.