Congenital Heart Defects (CHD) have a neonatal incidence of 0.8-1%1,2. Despite abundant examples of monogenic CHD in humans and mice, CHD has a low absolute sibling recurrence risk (~2.7%)3, suggesting a considerable role for de novo mutations (DNM), and/or incomplete penetrance4,5. De novo protein-truncating variants (PTVs) have been shown to be enriched among the 10% of ‘syndromic’ patients with extra-cardiac manifestations6,7. We exome sequenced 1,891 probands, including both syndromic (S-CHD, n=610) and non-syndromic cases (NS-CHD, n=1,281). In S-CHD, we confirmed a significant enrichment of de novo PTVs, but not inherited PTVs, in known CHD-associated genes, consistent with recent findings8. Conversely, in NS-CHD we observed significant enrichment of PTVs inherited from unaffected parents in CHD-associated genes. We identified three novel genome-wide significant S-CHD disorders caused by DNMs in CHD4, CDK13 and PRKD1. Our study reveals distinct genetic architectures underlying the low sibling recurrence risk in S-CHD and NS-CHD.

Previous studies have shown that copy-number variants (CNVs) contribute to the risk of complex developmental phenotypes. However, the contribution of global CNV burden to the risk of sporadic congenital heart disease (CHD) remains incompletely defined. We generated genome-wide CNV data by using Illumina 660W-Quad SNP arrays in 2,256 individuals with CHD, 283 trio CHD-affected families, and 1,538 controls. We found association of rare genic deletions with CHD risk (odds ratio [OR] = 1.8, p = 0.0008). Rare deletions in study participants with CHD had higher gene content (p = 0.001) with higher haploinsufficiency scores (p = 0.03) than they did in controls, and they were enriched with Wnt-signaling genes (p = 1 × 10(-5)). Recurrent 15q11.2 deletions were associated with CHD risk (OR = 8.2, p = 0.02). Rare de novo CNVs were observed in ~5% of CHD trios; 10 out of 11 occurred on the paternally transmitted chromosome (p = 0.01). Some of the rare de novo CNVs spanned genes known to be involved in heart development (e.g., HAND2 and GJA5). Rare genic deletions contribute ~4% of the population-attributable risk of sporadic CHD. Second to previously described CNVs at 1q21.1, deletions at 15q11.2 and those implicating Wnt signaling are the most significant contributors to the risk of sporadic CHD. Rare de novo CNVs identified in CHD trios exhibit paternal origin bias.

Rationale: Familial recurrence studies provide strong evidence for a genetic component to the predisposition to sporadic, non-syndromic Tetralogy of Fallot (TOF), the most common cyanotic congenital heart disease (CHD) phenotype. Rare genetic variants have been identified as important contributors to the risk of CHD, but relatively small numbers of TOF cases have been studied to date. Objective: We used whole exome sequencing (WES) to assess the prevalence of unique, deleterious variants in the largest cohort of non-syndromic TOF patients reported to date. Methods and Results: 829 TOF patients underwent WES. The presence of unique, deleterious variants was determined; defined by their absence in the Genome Aggregation Database (gnomAD) and a scaled combined annotation-dependent depletion (CADD) score of ≥20. The clustering of variants in two genes, NOTCH1 and FLT4, surpassed thresholds for genome-wide significance (assigned as P<5x10-8) after correction for multiple comparisons. NOTCH1 was most frequently found to harbour unique, deleterious variants. 31 changes were observed in 37 probands (4.5%; 95% confidence interval [CI]:3.2-6.1%) and included seven loss-of-function variants 22 missense variants and two in-frame indels. Sanger-sequencing of the unaffected parents of seven cases identified five de novo variants. Three NOTCH1 variants (p.G200R, p.C607Y and p.N1875S) were subjected to functional evaluation and two showed a reduction in Jagged1-induced NOTCH signalling. FLT4 variants were found in 2.4% (95% CI:1.6-3.8%) of TOF patients, with 21 patients harbouring 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.

We carried out a genome-wide association study (GWAS) of congenital heart disease (CHD). Our discovery cohort comprised 1,995 CHD cases and 5,159 controls, and included patients from each of the three major clinical CHD categories (septal, obstructive and cyanotic defects). When all CHD phenotypes were considered together, no regions achieved genome-wide significant association. However, a region on chromosome 4p16, adjacent to the MSX1 and STX18 genes, was associated (P=9.5×10−7) with the risk of ostium secundum atrial septal defect (ASD) in the discovery cohort (N=340 cases), and this was replicated in a further 417 ASD cases and 2520 controls (replication P=5.0×10−5; OR in replication cohort 1.40 [95% CI 1.19-1.65]; combined P=2.6×10−10). Genotype accounted for ~9% of the population attributable risk of ASD.

SUMMARY Fourteen newborn babies of different gestational ages (33 to 40 weeks) but similar postnatal age (four to 19 days) were studied during bottle‐feeding using real‐time ultrasonography, combined with respiratory monitoring. Previously undescribed tongue movements and graded changes in the temporal relationships between tongue movements, swallowing and breathing were observed among infants of differing maturity. These were most marked in the least mature infants, but were occasionally seen in term infants. The results suggest that adequate neuromuscular co‐ordination is more a function of gestational maturity than of postnatal sucking experience. The pattern of intraoral events for infants of differing maturity described in this study provides a framework for the study of feeding problems of term and preterm infants. RÉSUMÉ Développement de la coordination, de la succion, de la déglutition et de la respiration chez les nourrissons nés à terme et chez les prématurés Quatorze nouveaux‐nés d'âges differents de gestation (33 à 40 semaines) mais d'âges post‐nataux semblables (quatre à 19 jours) on*** été étudiés durant l'alimentation au biberon en utilisant une échographie en temps reel combinée avec un contrôle respiratoire. Des mouvements de langue non décrits antérieurement et des modifications graduées dans les relations temporelles entre les mouvements de langue, la déglutition et la respiration ont été observés chez les nourrissons de differentes maturités. Ils étaient au plus élevé chez les moins matures des enfants étudiés mais observés occasionnellement chez les nourrissons à terme. Les résultats suggèrent que la coordination neuro‐musculaire adéquate est plus une fonction de la maturité de gestation que de l'expérience post‐natale de succion. La distribution des évènements intra‐oraux pour les nourrissons de differentes maturités décrites dans cette étude fournit une base de travail pour l'étude des problèmes d'alimentation chez les nourrissons à terme et prématurés. ZUSAMMENFASSUNG Koordinationsentwicklung von Saugen, Schlucken und Atmen bei reif‐ und frühgeborenen Kindern Bei 14 Neugeborenen mit verschiedenem Gestationsalter (33 bis 40 Wochen), aber etwa gleichem Lebensalter (vier bis 19 Tage) wurden während der Flaschenfütterung Real‐Zeit Ultraschalluntersuchungen mit gleichzeitigen Aufzeichnungen der Atmung durchgeführt. Es wurden bisher nicht beschriebene Zungenbewegungen und abgestufte Veränderungen in der zeitlichen Relation zwischen Zungenbewegungen, Schlucken und Atmen bei Kindern mit unterschiedlichem Reifegrad festgestellt. Diese waren bei den unreifsten Kindern am ausgeprägtesten, wurden aber auch bei einigen reifen Kindern beobachtet. Die Ergebnisse zeigen, daβ eine richtige neuromuskuläre Koordination eher eine Funktion der Gestationsreife als der postnatalen Saugerfahrung ist. Die Muster intra‐oraler Abläufe bei Kindern unterschiedlicher Reife, die in dieser Studie beschrieben werden, bilden die Basis für Untersuchungen von Fütterungsproblemen bei reif‐ und frühgeborenen Kindern. RESUMEN D...

Recurrent rearrangements of chromosome 1q21.1 that occur via non-allelic homologous recombination have been associated with variable phenotypes exhibiting incomplete penetrance, including congenital heart disease (CHD). However, the gene or genes within the ∼1 Mb critical region responsible for each of the associated phenotypes remains unknown. We examined the 1q21.1 locus in 948 patients with tetralogy of Fallot (TOF), 1488 patients with other forms of CHD and 6760 ethnically matched controls using single nucleotide polymorphism genotyping arrays (Illumina 660W and Affymetrix 6.0) and multiplex ligation-dependent probe amplification. We found that duplication of 1q21.1 was more common in cases of TOF than in controls [odds ratio (OR) 30.9, 95% confidence interval (CI) 8.9–107.6); P = 2.2 × 10−7], but deletion was not. In contrast, deletion of 1q21.1 was more common in cases of non-TOF CHD than in controls [OR 5.5 (95% CI 1.4–22.0); P = 0.04] while duplication was not. We also detected rare (n = 3) 100–200 kb duplications within the critical region of 1q21.1 in cases of TOF. These small duplications encompassed a single gene in common, GJA5, and were enriched in cases of TOF in comparison to controls [OR = 10.7 (95% CI 1.8–64.3), P = 0.01]. These findings show that duplication and deletion at chromosome 1q21.1 exhibit a degree of phenotypic specificity in CHD, and implicate GJA5 as the gene responsible for the CHD phenotypes observed with copy number imbalances at this locus.

Atrial septal defect (ASD) is one of the most frequent congenital heart defects (CHDs) with a variable phenotypic effect depending on the size of the septal shunt. We identified two pedigrees comprising 20 members segregating isolated autosomal dominant secundum ASD. By genetic mapping, we identified the gene-encoding alpha-cardiac actin (ACTC1), which is essential for cardiac contraction, as the likely candidate. A mutation screen of the coding regions of ACTC1 revealed a founder mutation predicting an M123V substitution in affected individuals of both pedigrees. Functional analysis of ACTC1 with an M123V substitution shows a reduced affinity for myosin, but with retained actomyosin motor properties. We also screened 408 sporadic patients with CHDs and identified a case with ASD and a 17-bp deletion in ACTC1 predicting a non-functional protein. Morpholino (MO) knockdown of ACTC1 in chick embryos produces delayed looping and reduced atrial septa, supporting a developmental role for this protein. The combined results indicate, for the first time, that ACTC1 mutations or reduced ACTC1 levels may lead to ASD without signs of cardiomyopathy.

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