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.

Right atrial isomerism continues to have an associated high mortality despite surgical innovations. Management of pulmonary vein obstruction remains a serious problem and is associated with high mortality.

Our objective was to study neonates born to insulin-dependent diabetes mellitus (IDDM) mothers to detect the spectrum of congenital heart disease (CHD). Between July 2000 and June 2001, a prospective study of 100 consecutive infants of diabetic mothers (IDMs) at King Khalid University Hospital in Riyadh was undertaken. Family and maternal history, physical examination with special attention to the cardiovascular system, and echocardiography were performed. A total of 100 consecutive IDMs examined. The most common echocardiographic findings were patent ductus arteriosus (PDA; 70%), patent foramen ovale (68%), atrial septal defect (5%), small muscular ventricular septal defect (4%), mitral valve prolapse (2%), and pulmonary stenosis (1%). Hypertrophic cardiomyopathy (HCMP) was observed in 38% of cases, mainly hypertrophy of the interventricular septum. Severe forms of CHD encountered were D-transposition of great arteries, tetralogy of Fallot, and hypoplastic left heart syndrome (1% each). Isolated aortic stenosis and coarctation of aorta were not encountered in this series. Overall incidence of congenital heart disease was 15% after excluding PDA and HCMP. Maternal IDDM is a significant risk factor for CHD. Careful evaluation and early diagnosis of CHD in this high-risk group are highly indicated. There is a need for development of prenatal screening programs for CHD in our population.

While early diagnosis and repair of anomalous origin of one pulmonary artery from the ascending aorta is necessary, restenosis of the site of repair is common.