Risk Of Tetralogy Of Fallot Research Articles

Human Genetics of Tetralogy of Fallot and Double-Outlet Right Ventricle.

Tetralogy of Fallot (TOF) and double-outlet right ventricle (DORV) are conotruncal defects resulting from disturbances of the second heart field and the neural crest, which can occur as isolated malformations or as part of multiorgan syndromes. Their etiology is multifactorial and characterized by overlapping genetic causes. In this chapter, we present the different genetic alterations underlying the two diseases, which range from chromosomal abnormalities like aneuploidies and structural mutations to rare singlenucleotide variations affecting distinct genes. For example, mutations in the cardiac transcription factors NKX2-5, GATA4, and HAND2 have been identified in isolated TOF cases, while mutations of TBX5 and 22q11 deletion, leading to haploinsufficiency of TBX1, cause Holt-Oram and DiGeorge syndrome, respectively. Moreover, genes involved in signaling pathways, laterality determination, and epigenetic mechanisms have also been found mutated in TOF and/or DORV patients. Finally, genome-wide association studies identified common singlenucleotide polymorphisms associated with the risk for TOF.

Evaluation of Fetal Cardiac Size and Shape: A New Screening Tool to Identify Fetuses at Risk for Tetralogy of Fallot.

Prenatal detection rates for tetralogy of Fallot (TOF) vary between 23 and 85.7%, in part because of the absence of significant structural abnormalities of the 4-chamber view (4CV), as well as the relative difficulty in detection of abnormalities during the screening examination of the outflow tracts. The purpose of this study was to evaluate whether the 4CV and ventricles in fetuses with TOF may be characterized by abnormalities of size and shape of these structures. This study retrospectively evaluated 44 fetuses with the postnatal diagnosis of TOF. Measurements were made from the 4CV (end-diastolic length, width, area, global sphericity index, and cardiac axis) and the right (RV) and left (LV) ventricles (area, length, 24-segment transverse widths, sphericity index, and RV/LV ratios). Logistic regression analysis was performed to identify variables that might separate fetuses with TOF from normal controls. The mean gestational age at the time of the last examination prior to delivery was 28 weeks 5 days (SD 4 weeks, 4 days). The mean z-scores were significantly lower in fetuses with TOF for the 4CV and RV and LV measurements of size and shape. Logistic regression analysis identified simple linear measurements of the 4CV, RV, and LV that had a sensitivity of 90.9 and specificity of 98.5% that outperformed the 4CV cardiac axis (sensitivity of 22.7%) as a screening tool for TOF. Measurements of the 4CV, RV, and LV can be used as an adjunct to the outflow tract screening examination to identify fetuses with TOF.

The Functional Polymorphism R129W in the BVES Gene Is Associated with Sporadic Tetralogy of Fallot in the Han Chinese Population.

Background: Tetralogy of Fallot (TOF) accounts for ∼10% of congenital heart disease cases. The blood vessel epicardial substance (BVES) gene has been reported to play a role in the function of adult hearts. However, whether allelic variants in BVES contribute to the risk of TOF and its possible mechanism remains unknown. Methods: The open reading frame of the BVES gene was sequenced using samples from 146 TOF patients and 100 unrelated healthy controls. qRT-PCR and western blot assays were used to confirm the expression of mutated BVES variants in the TOF samples. The online software Polyphen2 and SIFT were used to predict the deleterious effects of the observed allelic variants. The effects of these allelic variants on the transcriptional activities of genes were examined using dual-fluorescence reporter assays. Results: We genotyped four single nucleotide polymorphisms (SNPs) in the BVES gene from each of the 146 TOF patients. Among them, the minor allelic frequencies of c.385C>T (p.R129W) were 0.035% in TOF, but ∼0.025% in 100 controls and the Chinese Millionome Database. This allelic variant was predicted to be a potentially harmful alteration by the Polyphen2 and SIFT softwares. qRT-PCR and western blot analyses indicated that the expression of BVES in the six right ventricular outflow tract samples with the c.385C>T allelic variant was significantly downregulated. A dual-fluorescence reporter system showed that the c.385C>T allelic variant significantly decreased the transcriptional activity of the BVES gene and also decreased transcription from the GATA4 and NKX2.5 promoters. Conclusions: c.385C>T (p.R129W) is a functional SNP of the BVES gene that reduces the transcriptional activity of BVES in vitro and in vivo in TOF tissues. This subsequently affects the transcriptional activities of GATA4 and NKX2.5 related to TOF. These findings suggest that c.385C>T may be associated with the risk of TOF in the Han Chinese population.

Functional polymorphisms of the neuropilin 1 gene are associated with the risk of tetralogy of Fallot in a Chinese Han population

Tetralogy of Fallot (TOF) is one of the most severe forms of cyanotic congenital heart disease (CHD) and is also the most common. Previous genome-wide association study (GWAS) and replication studies have suggested that a polymorphism in the neuropilin 1 (NRP1) gene is significantly associated with the risk of TOF. To further confirm the association between the NRP1 polymorphism and the risk of TOF and to identify additional positive functional single-nucleotide polymorphisms (SNPs) for TOF risk, we systematically screened for functional polymorphisms throughout the regulatory and coding regions of the NRP1 gene. A total of 11 functional SNPs in 747 Chinese Han individuals, including 314 TOF patients and 433 healthy controls, were genotyped using the MassARRAY system and GeneScan. The results revealed that the allelic and genotypic frequencies of the NRP1 polymorphism rs2228638 were strongly associated with the risk of TOF (p = 0.002 and 0.001, respectively). To increase the robustness of rs2228638 as a TOF risk SNP, we conducted a meta-analysis that combined published studies and our current case-control study. The meta-analysis showed that the T allele of the NRP1 polymorphism rs2228638 was significantly associated with an increased risk of TOF in the combined population, which included European and Chinese Han individuals [combined p < 0.00001, odds ratio (OR) = 1.53, 95% confidence interval (95% CI) = 1.35–1.73]. In addition, the association analysis suggested for the first time that there is a strong association between the allele distribution of rs10080 and susceptibility to TOF (p = 0.001). Our data provide further evidence of the association between NRP1 polymorphisms and TOF risk, and suggest that rs2228638 may be an excellent marker for TOF risk in European and Chinese Han populations.

Proportion of selected congenital heart defects attributable to recognized risk factors

PurposeTo assess the contribution of multiple risk factors for two congenital heart defects—hypoplastic left heart syndrome (HLHS) and tetralogy of Fallot (TOF). MethodsWe used data from the National Birth Defects Prevention Study (1997–2011) to estimate average adjusted population attributable fractions for several recognized risk factors, including maternal prepregnancy overweight–obesity, pregestational diabetes, age, and infant sex. ResultsThere were 594 cases of isolated simple HLHS, 971 cases of isolated simple TOF, and 11,829 controls in the analysis. Overall, 57.0% of HLHS cases and 37.0% of TOF cases were estimated to be attributable to risk factors included in our model. Among modifiable HLHS risk factors, maternal prepregnancy overweight–obesity accounted for the largest proportion of cases (6.5%). Among modifiable TOF risk factors, maternal prepregnancy overweight–obesity and maternal age of 35 years or older accounted for the largest proportions of cases (8.3% and 4.3%, respectively). ConclusionsApproximately half of HLHS cases and one-third of TOF cases were estimated to be attributable to risk factors included in our models. Interventions targeting factors that can be modified may help reduce the risk of HLHS and TOF development. Additional research into the etiology of HLHS and TOF may reveal other modifiable risk factors that might contribute to primary prevention efforts.

VEGF Gene Polymorphisms are Associated with Risk of Tetralogy of Fallot.

BackgroundThe aim of this study was to investigate associations of 3 common polymorphisms in the VEGF gene, −2578C>A, −634C>G, and 936C>T, with risk of tetralogy of Fallot (TOF) in Chinese Han children.Material/MethodsFrom January 2010 to June 2013, a total of 400 pediatric subjects were recruited, including 160 cases with TOF (TOF group) and 240 healthy controls (control group). The genotypes of 3 common VEGF polymorphisms, −2578C>A, −634C>G, and 936C>T, were analyzed by polymerase chain reaction restriction fragment length polymorphism. All data were analyzed with SPSS 18.0 software.ResultsNo significant differences were observed in body mass index or sex between TOF patients and controls (both P>0.05), but significant differences in age and family history of TOF were observed between the 2 groups (both P<0.05). The AA genotype in -2578C>A of VEGF was correlated with a significantly increased risk of TOF, and TOF risk in A allele carrier was 1.54-fold higher than that of C allele carrier (OR=1.54, 95%CI=1.14–2.09, P=0.005); the statistical significance was still present after Bonferroni correction (Pc=0.045). GG genotype in −634C>G of VEGF gene was also associated with an increased risk of TOF, and TOF risk in patients with G allele was 1.62-fold higher compared to patients with C allele (OR=1.62, 95%CI=1.19–2.21, P=0.002); the statistical significance was still present after Bonferroni correction (Pc=0.018). Interestingly, T allele in VEGF 936C>T polymorphism is associated with a decreased TOF risk (OR=0.65, 95%CI=0.49–0.87, P=0.003, the statistical significance was still present after Bonferroni correction (Pc=0.027). The result of logistic regression analysis revealed that −2578C>A, −634C>G, and 936C>T genotypes are independently related to the prevalence of TOF (all P<0.05).ConclusionsOur results confirmed that VEGF genetic polymorphisms, −2578C>A and −634C>G, may be associated with an increased TOF risk, while 936C>T polymorphism may be associated with decreased TOF risk.

Abstract 16184: Elevated Maternal Glucose Levels During Gestation may Confer Specific Risk for Tetralogy of Fallot

Introduction: Clinicians have long observed an association between maternal diabetes and risk of congenital heart disease (CHD) in offspring. Though the clinical diagnoses of Type 2 diabetes or gestational diabetes are strong maternal risk factors, this diagnostic classification captures only a subset of patients with overt hyperglycemia not more subtle abnormalities of glucose or insulin metabolism. We explored the potential risk for two different CHD phenotypes in offspring with with midpregnancy measures of glucose, insulin, and insulin resistance. Hypothesis: We hypothesize that continuous measures of blood analytes related to maternal diabetes will be associated with the risk for two CHD phenotypes tetralogy of Fallot (ToF) and d-Transposition of the Great Arteries (dTGA) which have been recently associated with overt diabetes. Methods: We assembled a prospective cohort of 277 women carrying infants with ToF (n=55), dTGA (n=42), or nonmalformed control infants without CHD (n=180), and measured serum insulin by a validated radioimmunoassay and glucose levels in second trimester blood samples. We performed univariable as well as multivariable analyses to investigate statistical associations. Results: Maternal glucose levels were associated with elevated risk for both CHD phenotypes in offspring with an adjusted odds ratio (OR) of 6.61 (95%CI 1.67-26.13), which in subgroup analysis was driven by a strong association with ToF (OR 18.45, 95%CI 3.34-102.08) compared to the much lower OR for dTGA (OR 1.24, 95%CI 0.16-9.59). Conclusions: We observed that maternal blood glucose levels are strongly associated with risk for ToF, which is consistent with recent epidemiological data. These results represent the first direct correlation of glucose as a continuous variable to risk for specific cardiac malformations. In conclusion the association between serum glucose and risk for ToF suggest the need for additional epidemiological and mechanistic investigations into the risk for conferred by insulin signaling and glucose metabolism during early pregnancy.

Genetic variations of VEGF gene were associated with tetralogy of fallot risk in a Chinese Han population.

Tetralogy of Fallot (TOF) is one of the most common forms of congenital heart disease. In this study, we aimed at investigating the associations between genetic variations of vascular endothelial growth factor (VEGF) gene and the risk of TOF in a Chinese Han population. Our findings may contribute to a deeper understanding of TOF pathogenesis and better diagnostic and therapeutic suggestions. A total of 165 TOF patients and 240 controls from a Chinese Han population in Shenyang and Harbin were recruited in the current study. Nine single-nucleotide polymorphisms (SNPs) (-2578C/A, -460T/C, -1154G/A, -634G/C, 534C/T, +398G/A, +963C/T, 752C/T, 913G/A) were genotyped by the MALDI-TOF MassARRAY system. Individual SNPs as well as their haplotypes were analyzed for their associations with TOF risk, using odds ratios and the 95% confidence interval under codominant and dominant models. In the single SNP analyses, the mutant homozygous genotypes of -2578C/A (rs699947) and +963C/T (rs3025039) were related with an increased risk of TOF. In addition, carriers with the mutant A allele of -1154G/A (rs1570360) were supposed to have a significantly elevated TOF risk. Similarly, compared with the wild homozygote GG carriers, the GC carrier of -634G/C (rs2010963) revealed a significant relationship with susceptibility of TOF, but not for the mutant homozygote CC carriers. However, no significant association was found for the other five SNPs. Meanwhile, haplotype analysis revealed that CCA and ATA in block 1 (-2578C/A, -460T/C, and -1154G/A) and TTG and TCA in block 3 (+963C/T, 752C/T, and 913G/A) were significantly related with an increased TOF risk compared with the most common haplotypes. In summary, our results suggested that VEGF variants (-2578C/A, -1154G/A, -634G/C, +963G/A) were involved in the susceptibility of TOF. However, validation of our study needs further study in various ethnics to reveal the functional relationship between VEGF polymorphisms and TOF risk, which may contribute to diagnosis and therapy of TOF.

MiR-196a2 rs11614913 T>C Polymorphism is Associated with an Increased Risk of Tetralogy of Fallot in a Chinese Population.

MicroRNAs (miRNAs) are a family of endogenous, small, noncoding single-stranded RNAs that act as post-transcriptional gene regulatory elements. MiRNA polymorphisms may be associated with susceptibility to congenital heart disease (CHD). The aim of this study was to evaluate the impact of miRNA single nucleotide polymorphisms (SNPs) on CHD susceptibility. We genotyped two functional SNPs, miR-196a2 rs11614913 and miR-146a rs2910164, in a case-control cohort of 173 Chinese patients with tetralogy of Fallot (TOF) and 207 non-CHD controls. When the miR-196a2 rs11614913 TT homozygote genotype was used as the reference group, the TC genotype was not associated with an increased risk of TOF. The CC genotype was associated with a borderline significantly increased risk for TOF. In the recessive model, when the miR-196a2 rs11614913 TT/TC genotypes were used as the reference group, the CC homozygote genotype was associated with a significantly increased risk of TOF (OR = 1.96, 95% CI = 1.18-3.25, p = 0.01). The miR-146a rs2910164 C>G polymorphism was not associated with developing TOF. Our findings suggested that the miR-196a2 rs11614913 T>C polymorphism may play a role in the development of TOF. Future larger studies that include populations of other ethnicities are required to confirm these findings. Congenital heart disease; MiRNA; Molecular epidemiology; Polymorphisms; Tetralogy of Fallot.

Genetic Variants at 10p11 Confer Risk of Tetralogy of Fallot in Chinese of Nanjing

A recent genome-wide association study (GWAS) has identified a new subset of susceptibility loci of Tetralogy of Fallot (TOF), one form of cyanotic congenital heart disease (CHD), on chromosomes 10p11, 10p14, 12q24, 13q31, 15q13 and 16q12 in Europeans. In the current study, we conducted a case-control study in a Chinese population including 1,010 CHD cases [atrial septal defect (ASD), ventricular septal defect (VSD) and TOF] and 1,962 controls to evaluate the associations of these loci with risk of CHD. We found that rs2228638 in NRP1 on 10p11 was significantly increased the risk of TOF (OR = 1.52, 95% CI = 1.13–2.04, P = 0.006), but not in other subgroups including ASD and VSD. In addition, no significant associations were observed between the other loci and the risk of ASD, VSD or TOF. Our results suggested that the genetic variants on 10p11 may serve as candidate markers for TOF susceptibility in Chinese population.

Polymorphisms of VEGF, TGFβ1, TGFβR2 and conotruncal heart defects in a Chinese population

Genetic variants may determine susceptibility of congenital heart disease (CHD). To evaluate the impact of transforming growth factor-β1 (TGFβ1), TGFβ receptor II (TGFβR2) and vascular endothelial growth factor (VEGF) polymorphisms on conotruncal heart defects susceptibility, we genotyped six functional polymorphisms TGFβ1 rs1800469 C>T, TGFβR2 rs3087465 G>A, VEGF -2578C>A, -1498T>C, -634G>C and +936C>T in a hospital based case-control study of 244 conotruncal heart defects cases and 136 non-CHD controls in a Chinese population. Logistic regression analyses revealed that if the TGFβ1 rs1800469 CC homozygote genotype was used as the reference group, subjects carrying the CT variant heterozygote had a significant 0.48-fold decreased risk of conotruncal heart defects [odds ratio (OR) = 0.52; 95% confidence interval (CI) = 0.30-0.88], subjects carrying the TT variant homozygote had a significant 0.47-fold decreased risk of conotruncal heart defects (OR 0.53; 95% CI 0.28-1.00). In stratification analyses, the TGFβ1 rs1800469 C>T genotype was associated with a decreased risk for tetralogy of fallot in homozygote comparisons (OR 0.47; 95% CI 0.22-0.99), a decreased risk for transposition of great artery in the dominant genetic model (OR 0.49; 95 % CI 0.28-0.87) and heterozygote comparisons (OR 0.45; 95% CI 0.24-0.83). Our findings suggest that TGFβ1 rs1800469 C>T polymorphism was significantly associated with decreased risk of conotruncal heart defects. TGFβR2 rs3087465 G>A, VEGF -2578C>A, -1498T>C, -634G>C and +936C>T polymorphisms may not play a role in the susceptibility of conotruncal heart defects.

MTHFR rs1801133 C&gt;T polymorphism is associated with an increased risk of tetralogy of Fallot

Abnormal folate metabolism and common variants of folate-metabolizing enzymes have been described as possible risk factors for congenital heart disease (CHD). Two important folate-metabolizing enzymes involved in the folate/homocysteine metabolic pathway are 5,10-methylenetetrahydrofolate reductase (MTHFR) and methylenetetrahydrofolate dehydrogenase 1 (MTHFD1). MTHFR and MTHFD1 polymorphisms may be associated with CHD susceptibility. To evaluate the impact of MTHFR and MTHFD1 single-nucleotide polymorphisms (SNPs) on CHD susceptibility, we genotyped functional MTHFR SNPs rs1801133 C>T, rs1801131 A>C and rs2274976 G>A, and MTHFD SNPs rs2236225 C>T, rs1950902 G>A and rs1076991 A>G in a hospital-based case-control study of 173 tetralogy of Fallot (TOF) cases and 207 non-CHD controls. When MTHFR rs1801133 CC homozygote genotype was used as the reference group, the TT genotype was associated with a significantly increased risk for TOF [TT vs. CC: odds ratio (OR)=1.67; 95% confidence interval (CI): 1.01-2.75; P=0.046]. In the recessive model, when MTHFR rs1801133 CC/CT genotype was used as the reference group, the TT homozygote genotype was associated with a significantly increased risk for TOF (OR=1.81, 95% CI: 1.15-2.84; P=0.010). In conclusion, our findings suggest that MTHFR rs1801133 C>T polymorphism may play a role in susceptibility for TOF. Large-scale studies with a more rigorous study design including diverse ethnic populations are required to confirm these findings.

Assessing the role of multiple pregnancies in the association between tetralogy of Fallot and assisted reproductive techniques: a path-analysis approach

BackgroundAssisted reproductive techniques (ART) are associated with a higher risk of tetralogy of Fallot (TOF) and multiple pregnancies may be associated with a higher risk of congenital anomalies. We assessed the extent to which the association between ART and risk of TOF may be mediated by the higher risk of multiple pregnancies associated with ART.MethodsWe conducted a case–control study using population-based data from the Paris Registry of Congenital Malformations for the period 1987–2009 and a cohort study of congenital heart defects (EPICARD). The study population included 395 cases of TOF and 4104 malformed controls with no known associations with ART. The analysis was based on a path-analysis model using a counterfactual approach, which allows decomposition of the total effect of ART into an indirect effect (that mediated by the association between ART and multiple pregnancies) and a direct effect.ResultsART (all methods combined) were associated with a 2.6-fold higher odds of TOF after adjustment for maternal and paternal characteristics and year of birth (adjusted OR 2.6, 95% CI, 1.5-4.5). Most (79%) of the effect associated with ART was a direct effect (i.e., not mediated by multiple pregnancies), whereas 21% of the effect of ART was due to its association with multiple pregnancies (i.e., the indirect effect). In vitro fertilization with intracytoplasmic sperm injection was associated with a 3.5-fold higher odds of TOF (adjusted OR 3.5, 95% CI, 1.1-11.2); 11% of this effect was mediated through the association of ICSI with multiple pregnancies.ConclusionsBy far, most of the higher risk of TOF associated with ART is a direct effect and only a small proportion of the effect may be mediated by multiple pregnancies.

Use of Oral Fluconazole During Pregnancy and the Risk of Birth Defects

Whether common doses of oral fluconazole used in treating fungal infections of the skin or mucous membranes increase the risk of specific birth defects remains a concern. The teratogenic potential of oral azole antifungal agents is important because pregnant women are at increased risk for vaginal candidiasis, the most common clinical indication for these drugs. This registry-based, nationwide cohort study evaluated the association between first-trimester oral fluconazole exposure and the risk of major birth defects. Using a nationwide cohort of all live-born infants born between 1996 and 2011, data were obtained on prescriptions for oral fluconazole, itraconazole, and ketoconazole that were filled by the cohort women during their pregnancies. Unexposed women were those who did not fill prescriptions for oral azole antifungal agents during the first trimester. The 15 specific birth defects previously associated with azole antifungal agents were craniosynostosis, cleft palate, cleft lip with or without cleft palate, other craniofacial defects, middle ear defects, limb defects, limb reduction defects, polydactyly, syndactyly, diaphragmatic hernia, heart defects, tetralogy of Fallot (TOF), pulmonary artery hypoplasia, ventricular septal defects, and hypoplastic left heart. Chromosomal aberrations, genetic syndromes, birth defect syndromes with known causes, congenital viral infections associated with malformations, and minor defects were excluded. Prevalence odds ratios (ORs) with 95% confidence intervals (CIs) were estimated by logistic regression for each exposure category and each birth defect outcome. Primary analyses included any exposure to fluconazole or exposure to different fluconazole doses and the outcome of either birth defects overall or birth defects linked with azole antifungal agents. Categories of cumulative doses during the first trimester were 150, 300, and 350 to 6000 mg, based on the standard treatment of vaginal candidiasis. Secondary analyses included exposure to itraconazole and ketoconazole and the outcome of birth defects overall. A total of 976,300 live-born infants were included in the study. No significantly increased risk of birth defects overall was observed among 7352 pregnancies exposed to any fluconazole, as compared with 968,236 unexposed pregnancies (adjusted prevalence OR, 1.06; 95% CI, 0.92–1.21); evaluation of exposure using the cumulative doses did not change this result. No significantly increased risk was found for 14 of the defects, with the only exception being TOF. Based on 7 exposed pregnancies, the risk of TOF was 3 times higher (prevalence 0.10%) than that among 287 unexposed pregnancies (prevalence, 0.03%; adjusted prevalence OR, 3.16; 95% CI, 1.49–6.71). Similar results were observed when the 15 birth defects were evaluated according to cumulative fluconazole dose. No significantly increased risk of birth defects overall was observed among the 687 and 72 pregnancies exposed to itraconazole and ketoconazole, respectively, and no clustering of malformations was observed. Exposure to any oral fluconazole or to the described cumulative doses during the first trimester of pregnancy was not associated with significantly increased risks of birth defects overall, nor was exposure to oral itraconazole or ketoconazole. The only birth defect at higher risk was TOF, but the absolute risk was small. However, this association should be confirmed in future studies.

Racial/ethnic disparities in timing of death during childhood among children with congenital heart defects

Infants with congenital heart defects (CHD) have increased risk of morbidity and mortality. Little is known about racial/ethnic differences in timing of death during childhood. Our intent was to investigate racial/ethnic differences in mortality for CHDs during specific time periods in childhood. Texas Birth Defect Registry data were used for a retrospective cohort study with 30,015 singleton infants with a CHD, born January 1, 1999, to December 31, 2007, to non-Hispanic (NH) white, NH-black, or Hispanic women. Texas Birth Defect Registry data were linked to Texas death records to ascertain death. Kaplan-Meier survival probabilities and multivariable Cox-proportional hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated. NH-blacks and Hispanics with specific CHDs had increased mortality during the postneonatal period and early childhood. NH-blacks had increased postneonatal mortality compared with NH-whites for transposition of the great arteries (HR = 2.4; 95% CI, 1.5-4.0), pulmonary valve atresia without ventricular septal defect (HR = 4.1; 95% CI, 1.7-9.7), Ebstein's anomaly (HR = 8.6; 95 CI, 1.2-61.1), hypoplastic left heart syndrome (HR = 2.1; 95% CI, 1.2-3.7), coarctation of the aorta (HR = 2.1; 95% CI, 1.2-3.5), ventricular septal defect (HR = 2.1; 95% CI, 1.6-2.8), and atrial septal defect (HR = 1.4; 95% CI, 1.1-1.8). Hispanics had increased postneonatal mortality risk for tetralogy of Fallot (HR = 2.0; 95% CI, 1.1-3.5). Racial/ethnic increases in mortality risk were also observed during infancy and childhood. Racial/ethnic differences in mortality were most notably observed during the postneonatal period and early childhood. Future studies should assess factors associated with this disparity in mortality risk for infants with CHDs.

Low-frequency intermediate penetrance variants in the ROCK1 gene predispose to Tetralogy of Fallot

BackgroundEpidemiological studies indicate a substantial excess familial recurrence of non-syndromic Tetralogy of Fallot (TOF), implicating genetic factors that remain largely unknown. The Rho induced kinase 1 gene (ROCK1) is a key component of the planar cell polarity signalling pathway, which plays an important role in normal cardiac development. The aim of this study was to investigate the role of genetic variation in ROCK1 on the risk of TOF.ResultsROCK1 was sequenced in a discovery cohort of 93 non-syndromic TOF probands to identify rare variants. TagSNPs were selected to capture commoner variation in ROCK1. Novel variants and TagSNPs were genotyped in a discovery cohort of 458 TOF cases and 1331 healthy controls, and positive findings were replicated in a further 209 TOF cases and 1290 healthy controls. Association between genotypes and TOF was assessed using LAMP.A rare SNP (c.807C > T; rs56085230) discovered by sequencing was associated with TOF risk (p = 0.006) in the discovery cohort. The variant was also significantly associated with the risk of TOF in the replication cohort (p = 0.018). In the combined cohorts the odds ratio for TOF was 2.61 (95% CI 1.58-4.30); p < 0.0001. The minor allele frequency of rs56085230 in the cases was 0.02, and in the controls it was 0.007. The variant accounted for 1% of the population attributable risk (PAR) of TOF. We also found significant association with TOF for an uncommon TagSNP in ROCK1, rs288979 (OR 1.64 [95% CI 1.15-2.30]; p = 1.5x10-5). The minor allele frequency of rs288979 in the controls was 0.043, and the variant accounted for 11% of the PAR of TOF. These association signals were independent of each other, providing additional internal validation of our result.ConclusionsLow frequency intermediate penetrance (LFIP) variants in the ROCK1 gene predispose to the risk of TOF.

Genome-wide association study identifies loci on 12q24 and 13q32 associated with tetralogy of Fallot.

We conducted a genome-wide association study to search for risk alleles associated with Tetralogy of Fallot (TOF), using a northern European discovery set of 835 cases and 5159 controls. A region on chromosome 12q24 was associated (P = 1.4 × 10−7) and replicated convincingly (P = 3.9 × 10−5) in 798 cases and 2931 controls [per allele odds ratio (OR) = 1.27 in replication cohort, P = 7.7 × 10−11 in combined populations]. Single nucleotide polymorphisms in the glypican 5 gene on chromosome 13q32 were also associated (P = 1.7 × 10−7) and replicated convincingly (P = 1.2 × 10−5) in 789 cases and 2927 controls (per allele OR = 1.31 in replication cohort, P = 3.03 × 10−11 in combined populations). Four additional regions on chromosomes 10, 15 and 16 showed suggestive association accompanied by nominal replication. This study, the first genome-wide association study of a congenital heart malformation phenotype, provides evidence that common genetic variation influences the risk of TOF.

The risk for four specific congenital heart defects associated with assisted reproductive techniques: a population-based evaluation

Are the risks of hypoplastic left heart syndrome, transposition of great arteries, tetralogy of Fallot (TOF) and coarctation of the aorta increased in infants conceived by different assisted reproductive techniques (ARTs)? ARTs, and particularly intracytoplasmic sperm injection (ICSI), are specifically associated with a higher risk of TOF. ARTs are associated with an increase in the overall risk of birth defects. The risk for congenital heart defects (CHDs) associated with ARTs has been evaluated as a whole but there is limited information on the risks for specific CHDs. STUDY DESIGN, MATERIAL AND METHODS: We conducted a case-control study using population-based data from the Paris registry of congenital malformations for the period 1987-2009 and a cohort study of CHD (EPICARD) on 1583 cases of CHDs and 4104 malformed controls with no known associations with ARTs. ARTs included ovulation induction only, IVF and ICSI. Exposure to ARTs was significantly higher for TOF than controls (6.6 versus 3.5%, P = 0.002); this was not the case for the other three CHDs. ARTs (all methods combined) were associated with a 2.4-fold higher odds of TOF after adjustment for maternal characteristics, paternal age and year of birth [adjusted odds ratios (OR): 2.4, 95% confidence interval (CI): 1.5-3.7] with the highest risk associated with ICSI (adjusted OR: 3.0, 95% CI: 1.0-8.9). No statistically significant associations were found for the other CHDs. Our study cannot disentangle to what extent the observed associations between the risk of TOF and ARTs are due to causal effects of ARTs and/or the underlying infertility problems of couples who conceive following ART. The developmental basis of the specific association between the risk of TOF and ARTs need to be further investigated.

Tetralogy of Fallot is an Uncommon Manifestation of Warts, Hypogammaglobulinemia, Infections, and Myelokathexis Syndrome

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is a rare immunodeficiency disorder. We report three patients with WHIM syndrome who are affected by Tetralogy of Fallot (TOF). This observation suggests a possible increased risk of TOF in WHIM syndrome and that birth presentation of TOF and neutropenia should lead to suspect WHIM syndrome.

A variant in the carboxyl-terminus of connexin 40 alters GAP junctions and increases risk for tetralogy of Fallot

GJA5 gene (MIM no. 121013), localized at 1q21.1, encodes for the cardiac gap junction protein connexin 40. In humans, copy number variants of chromosome 1q21.1 have been associated with variable phenotypes comprising congenital heart disease (CHD), including isolated TOF. In mice, the deletion of Gja5 can cause a variety of complex CHDs, in particular of the cardiac outflow tract, corresponding to TOF in many cases. In the present study, we screened for mutations in the GJA5 gene 178 unrelated probands with isolated TOF. A heterozygous nucleotide change (c.793C>T) in exon 2 of the gene leading to the p.Pro265Ser variant at the carboxyl-terminus of the protein was found in two unrelated sporadic patients, one with classic anatomy and one with pulmonary atresia. This GJA5 missense substitution was not observed in 1568 ethnically-matched control chromosomes. Immunofluorescent staining and confocal microscopy revealed that cells expressing the mutant protein form sparse or no visible gap-junction plaques in the region of cell-cell contact. Moreover, analysis of the transfer of the gap junction permanent tracer lucifer yellow showed that cells expressing the mutant protein have a reduced rate of dye transfer compared with wild-type cells. Finally, use of a zebrafish model revealed that microinjection of the GJA5-p.Pro265Ser mutant disrupts overall morphology of the heart tube in the 37% (22/60) of embryos, compared with the 6% (4/66) of the GJA5 wild-type-injected embryos. These findings implicate GJA5 gene as a novel susceptibility gene for TOF.