Congenital Heart Diseases: Genetic Risk Variants and Their Methylation Status.

(1) Background: The interaction between single nucleotide variants (SNVs) associated with congenital heart diseases (CHDs) and their gene methylation status has not been well researched. The aim of the present study was to determine if there is a relationship between the methy lation status (MS) of genes and the allelic variants associated with CHDs. (2) Methods: Seven SNVs of the genes AXIN1, TBX1, TBX20, and MTHFR were selected from the literature. DNA extraction, genotyping, and a methylation analysis were performed on healthy subjects and subjects with CHDs. (3) Results: Twenty-two subjects with CHDs were selected as the case group (15 with ventricular septal defects (VSDs) and 7 with atrial septal defects (ASDs)), and 44 healthy subjects comprised the control group. The MTHFR and AXIN1 genes were hypermethylated in the control group when compared to the case group. When analyzed separately, those with atrial septum defects exhibited greater methylation, except for the gene MTHFR where there were no differences. Only the alternate alleles of MTHFR showed a significantly different methylation status in those without cardiopathy. (4) Conclusions: The MTHFR and AXIN genes were hypermethylated in the control group; however, only the alternate alleles of MTHFR (rs1801133 and rs1801131) showed a significantly different methylation status.

Maternal Folic Acid Intake and Methylation Status of Genes Associated with Ventricular Septal Defects in Children: Case-Control Study.

BACKGROUND: DNA methylation is the best epigenetic mechanism for explaining the interactions between nutrients and genes involved in intrauterine growth and development programming. A possible contributor of methylation abnormalities to congenital heart disease is the folate methylation regulatory pathway; however, the mechanisms and methylation patterns of VSD-associated genes are not fully understood. OBJECTIVE: To determine if maternal dietary intake of folic acid (FA) is related to the methylation status (MS) of VSD-associated genes (AXIN1, MTHFR, TBX1, and TBX20). METHODS: Prospective case-control study; 48 mothers and their children were evaluated. The mothers' dietary variables were collected through a food frequency questionnaire focusing on FA and the consumption of supplements with FA. The MS of promoters of genes was determined in the children. RESULTS: The intake of FA supplements was significantly higher in the control mothers. In terms of maternal folic acid consumption, significant differences were found in the first trimester of pregnancy. Significant differences were observed in the MS of MTHFR and AXIN1 genes in VSD and control children. A correlation between maternal FA supplementation and MS of AXIN1 and TBX20 genes was found in control and VSD children, respectively. CONCLUSIONS: A lower MS of AXIN1 genes and a higher MS of TBX20 genes is associated with FA maternal supplementation.

Left Ventricular Noncompaction Is More Prevalent in Ventricular Septal Defect Than Other Congenital Heart Defects: A Morphological Study.

Left ventricular noncompaction (LVNC) is a condition characterized by prominent ventricular trabeculae and deep intertrabecular recesses and has been described as a possible substrate for arrhythmias, thromboembolism, and heart failure. Herein, we explored the prevalence of LVNC morphology among hearts with congenital heart defects (CHD). We examined 259 postnatal hearts with one of the following CHD: isolated ventricular septal defect (VSD); isolated atrial septal defect (ASD); atrioventricular septal defect (AVSD); transposition of the great arteries (TGA); isomerism of the atrial appendages (ISOM); Ebstein's malformation (EB); Tetralogy of Fallot (TF). Eleven hearts from children who died of non-cardiovascular causes were used as controls. The thickness of the compacted and non-compacted left ventricular myocardial wall was determined and the specimens classified as presenting or not LVNC morphology according to three criteria, as proposed by Chin, Jenni, and Petersen. Normal hearts did not present LVNC, but the CHD group presented different percentages of LVNC in at least one diagnostic criterium. The prevalence of LVNC was respectively, according to Chin's, Jenni´s and Petersen´s methods: for VSD-54.2%, 35.4%, and 12.5%; ASD-8.3%, 8.3%, and 8.3%; AVSD-2.9%, 2.9%, and 0.0%; TGA-22.6%, 17%, and 5.7%; ISOM-7.1%, 7.1%, and 7.1%; EB-28.6%, 9.5%, and 0.0%; TF-5.9%. 2.9%, and 2.9%. VSD hearts showed a significantly greater risk of presenting LVNC when compared to controls (Chin and Jenni criteria). No other CHD presented similar risk. Current results show some agreement with previous studies, such as LVNC morphology being more prevalent in VSDs. Nonetheless, this is a morphological study and cannot be correlated with symptoms or severity of the CHD.

Prenatal exposure to zidovudine and risk for ventricular septal defects and congenital heart defects: data from the Antiretroviral Pregnancy Registry.

OBJECTIVE: To assess the risk for ventricular septal defects and congenital heart defects following zidovudine exposure during pregnancy using data from the Antiretroviral Pregnancy Registry. STUDY DESIGN: Data on 16,304 prospectively reported pregnancies were analyzed to estimate the frequency and risk of ventricular septal defects and congenital heart defects, comparing exposure between zidovudine-containing regimens and non-zidovudine antiretroviral regimens. The numerator includes defect cases in outcomes at ≥ 20 weeks of gestational age. The denominator includes live birth outcomes. Infants with chromosomal anomalies were excluded. RESULTS: There were 15,451 live birth outcomes; 13,073 were prenatally exposed to zidovudine-containing regimens and 2378 to non-zidovudine containing regimens. There were 36 ventricular septal defect cases: 31 exposed to prenatal zidovudine and 5 unexposed. Nine of the zidovudine-exposed cases had earliest exposure in the first trimester; 22 had second/third trimester exposure. Of the 5 ventricular septal defect cases not exposed to zidovudine, 2 had earliest exposure to non-zidovudine antiretroviral regimens in the first trimester, and 3 had exposure in the second/third trimester. The prevalence of ventricular septal defect was 0.24% (95% confidence interval: 0.16, 0.34) for infants exposed to zidovudine-containing regimens and 0.21% (95% confidence interval: 0.07, 0.49) for non-zidovudine regimens. The relative risk comparing the 2 was 1.13 (95% confidence interval: 0.44, 2.90). There were a total of 90 congenital heart defect cases; 78 were exposed prenatally to zidovudine-containing regimens, and 12 were unexposed. Twenty-six of the zidovudine-exposed cases had earliest exposure in the first trimester and 52 had second/third trimester exposure. Six congenital heart defect cases with non-zidovudine antiretroviral regimens had earliest exposure in the first trimester and 6 had exposure in the second/third trimester. The prevalence of congenital heart defects was 0.60% (95% confidence interval: 0.47, 0.74) for infants exposed to zidovudine-containing regimens and 0.50% (95% confidence interval: 0.26, 0.88) for non-zidovudine regimens. The relative risk comparing the 2 was 1.18 (95% confidence interval: 0.64, 2.17). CONCLUSIONS: The prevalence and risk of ventricular septal defects and congenital heart defects among infants exposed to zidovudine-containing regimens is not significantly different from the prevalence and risk in infants exposed to non-zidovudine containing regimens. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01137981.