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Rationale: Dextro-transposition of the great arteries (D-TGA) is a severe congenital heart defect which affects approximately 1 in 4,000 live births. While there are several reports of D-TGA patients with rare variants in individual genes, the majority of D-TGA cases remain genetically elusive. Familial recurrence patterns and the observation that most cases with D-TGA are sporadic suggest a polygenic inheritance for the disorder, yet this remains unexplored. Objective: We sought to study the role of common single nucleotide polymorphisms (SNPs) in risk for D-TGA. Methods and Results: We conducted a genome-wide association study in an international set of 1,237 patients with D-TGA and identified a genome-wide significant susceptibility locus on chromosome 3p14.3, which was subsequently replicated in an independent case-control set (rs56219800, meta-analysis P=8.6x10 -10 , OR=0.69 per C allele). SNP-based heritability analysis showed that 25% of variance in susceptibility to D-TGA may be explained by common variants. A genome-wide polygenic risk score derived from the discovery set was significantly associated to D-TGA in the replication set (P=4x10 -5 ). The genome-wide significant locus (3p14.3) co-localizes with a putative regulatory element that interacts with the promoter of WNT5A , which encodes the Wnt Family Member 5A protein known for its role in cardiac development in mice. We show that this element drives reporter gene activity in the developing heart of mice and zebrafish and is bound by the developmental transcription factor TBX20. We further demonstrate that TBX20 attenuates Wnt5a expression levels in the developing mouse heart. Conclusions: This work provides support for a polygenic architecture in D-TGA and identifies a susceptibility locus on chromosome 3p14.3 near WNT5A . Genomic and functional data support a causal role of WNT5A at the locus.

Objective To compare the risks of pregnancy complications in women with repaired and unrepaired isolated ventricular septal defect (VSD). Design A retrospective multicentre study. Setting Tertiary centres in the Netherlands and Belgium. Methods Women were identified using two congenital heart disease registries. Eighty-eight women were identified who had experienced 202 pregnancies, including 46 miscarriages and nine terminations of pregnancy. Information on each completed pregnancy (n = 147; unrepaired VSD, n = 104; repaired VSD, n = 43) was obtained using medical records and telephone interviews. Data from the Generation R database (prospective cohort study; n = 9667) were used to determine the background risk (controls). Odds ratios and 95% CI were estimated using general estimation equation analysis adjusted for multiple pregnancies per woman, maternal age and parity status. Main outcome measures Adjusted odds ratios (AORs) for developing pregnancy complications in relation to corrective status. Results Pregnancies in women with an unrepaired VSD were associated with a higher risk of pre-eclampsia (AOR 4.59, 95% CI 2.01-10.5, P < 0.001) compared with controls. No differences were observed when comparing women with repaired VSD and controls. Pregnancies in women with repaired VSD were associated with a higher risk of premature labour (AOR 4.02, 95% CI 1.12-14.4, P = 0.03) and small-for-gestational-age (SGA) births (AOR 4.09, 95% CI 1.27-13.2, P = 0.02) compared with women with unrepaired VSD. Conclusions Women with unrepaired VSD are at increased risk of pre-eclampsia, which suggests that it is not a benign condition. In addition, women with repaired VSD are at increased risk of premature labour and SGA births compared with women with unrepaired VSD.

Objective To compare the risks of complications during pregnancy in women with repaired and unrepaired atrial septal defects (ASDs) without associated complex cardiac lesions. Design A retrospective multicentre study. Setting Tertiary centres in the Netherlands and Belgium. Population Women with ASD without associated complex cardiac lesions. Methods Women were identified using two congenital heart disease registries. One hundred women were identified who had 243 pregnancies, including 49 miscarriages and six terminations of pregnancy. Detailed information on each completed pregnancy (n = 188; unrepaired ASD, n = 133; repaired ASD, n = 55) was obtained using medical records and telephone interviews. In addition, data from the Generation R database (a prospective cohort study; n = 9667) were used to determine the background risk (control group). Main outcome measures Adjusted odds ratios (AORs) for cardiac, obstetric and neonatal events controlled for multiple pregnancies per woman using general estimating equation analysis. Results Women with an unrepaired ASD had a higher risk of neonatal events (AOR = 2.99, 95% confidence interval [CI] 1.14-7.89, P = 0.027) than women with a repaired ASD. The risk of cardiac and obstetric complications was comparable between women with unrepaired and repaired ASDs. Compared with the general population, women with an unrepaired ASD had higher risks of pre-eclampsia (AOR = 3.54, 95% CI 1.26-9.98, P = 0.017), small-for-gestational-age births (AOR = 1.95, 95% CI 1.15-3.30, P = 0.013) and fetal mortality (AOR = 5.55, 95% CI 1.77-17.4, P = 0.003). By contrast, no differences were observed when comparing women with a repaired ASD versus controls. Conclusions Women with an unrepaired ASD are at increased risk of neonatal events in comparison with women with a repaired ASD. Compared with the general population, women with an unrepaired ASD are at increased risk of pre-eclampsia, small-for-gestational-age births and fetal mortality.