Congenital heart defects (CHDs) are the most common birth defect worldwide and are a leading cause of neonatal mortality. Nonsyndromic atrioventricular septal defects (AVSDs) are an important subtype of CHDs for which the genetic architecture is poorly understood. We performed exome sequencing in 13 parent-offspring trios and 112 unrelated individuals with nonsyndromic AVSDs and identified five rare missense variants (two of which arose de novo) in the highly conserved gene NR2F2, a very significant enrichment (p = 7.7 × 10(-7)) compared to 5,194 control subjects. We identified three additional CHD-affected families with other variants in NR2F2 including a de novo balanced chromosomal translocation, a de novo substitution disrupting a splice donor site, and a 3 bp duplication that cosegregated in a multiplex family. NR2F2 encodes a pleiotropic developmental transcription factor, and decreased dosage of NR2F2 in mice has been shown to result in abnormal development of atrioventricular septa. Via luciferase assays, we showed that all six coding sequence variants observed in individuals significantly alter the activity of NR2F2 on target promoters.

Supplementary data are available at Bioinformatics online.

Background For clinical genetic testing of cardiomyopathy (CMP), current guidelines do not address which gene panels to use: targeted panels specific to a CMP phenotype or expanded (panCMP) panels that include genes associated with multiple phenotypic subtypes. Aim Our objective was to assess the clinical utility of targeted versus panCMP panel testing in pediatric CMPs. Methods 151 pediatric patients with primary hypertrophic (n = 66), dilated (n = 64), restrictive (n = 8), or left‐ventricular non‐compaction (n = 13) CMP who underwent clinical genetic panel testing at a single centre were included. PanCMP (n = 47) and targeted panel testing (n = 104) were compared for yield of pathogenic variants and variants of unknown significance (VUS). Results Pathogenic variants were identified in 26% of patients, 42% had indeterminate results (only VUS detected), and 32% had negative results. Yield was lower (15%) in panCMP vs. targeted panel testing (32%) (P = .03) in all CMP subtypes. VUS detection was higher with panCMP (87%) than targeted panel testing (30%) (P <.0001). PanCMP panel testing only identified pathogenic variants in genes that overlapped targeted panels. Conclusion PanCMP testing did not increase diagnostic yield compared to targeted panel testing. Until accuracy of variant interpretation with panCMP panels improves, targeted panels may be suitable for clinical testing in pediatric CMP.

No abstract

Background: hypoxia-inducible factor (HIF1A) regulates the myocardial response to hypoxia and hemodynamic load. We investigated the association of HIF1A variants with right-ventricular (RV) remodeling after tetralogy of Fallot (TOF) repair. Methods: children with TOF were genotyped for three single-nucleotide polymorphisms in HIF1A. Genotypes were analyzed for association with RV myocardial protein expression and fibrosis at complete repair (n = 42) and RV dilation, fractional area change, and freedom from pulmonary valve/conduit replacement on follow-up. results: In 180 TOF patients, mean age at repair was 1.0 ± 0.8 y with follow-up at 9.0 ± 3.5 y; 82% had moderate to severe pulmonary insufficiency. Freedom from RV reinterventions at 5, 10, and 15 y was 92, 84, and 67%, respectively. Patients with more functioning HIF1A alleles had higher transforming growth factor β1 expression and more fibrosis at initial repair as compared with controls (P < 0.05). During follow-up, patients with more functioning HIF1A alleles showed less RV dilation, better preservation of RV function, and greater freedom from RV reinterventions (P < 0.05). This was confirmed in a replication cohort of 69 patients. conclusion: In children who have had TOF repair, a lower number of functioning HIF1A alleles was associated with RV dilation and dysfunction, suggesting that hypoxia adaptation in unrepaired TOF may influence RV phenotype after repair.

PurposeThe genetic etiology of atrioventricular septal defect (AVSD) is unknown in 40% cases. Conventional sequencing and arrays have identified the etiology in only a minority of non-syndromic individuals with AVSD.MethodsWhole exome sequencing was performed in 81 unrelated probands with AVSD to identify potentially causal variants in a comprehensive set of 112 genes with strong biological relevance to AVSD.ResultsA significant enrichment of rare and rare/damaging variants was identified in the gene set, compared with controls (odds ratio 1.52, 95% confidence interval 1.35–1.71, p = 4.8 x 10-11). The enrichment was specific to AVSD probands compared with a non-AVSD cohort with tetralogy of Fallot (odds ratio 2.25, 95% confidence interval 1.84-2.76, p = 2.2 x 10-16). Six genes (NIPBL, CHD7, CEP152, BMPR1a, ZFPM2 and MDM4) were enriched for rare variants in AVSD compared to controls, including three syndrome-associated genes (NIPBL, CHD7, CEP152). The findings were confirmed in a replication cohort of 81 AVSD probands.ConclusionMutations in genes with strong biological relevance to AVSD, including syndrome-associated genes, can contribute to AVSD even in those with isolated heart disease. The identification of a gene set associated with AVSD will facilitate targeted genetic screening in this cohort.

The high pediatric consent rate (90%) was comparable with that of adults. Ethical, social, or legal issues were not the leading reasons for refusal of consent.

No abstract