Personalized Genetic Diagnosis of Congenital Heart Defects in Newborns

Congenital heart diseases (CHDs) and forensic investigations: Searching for the cause of death

Congenital Heart Diseases (CHDs) are a group of structural abnormalities or defects of the heart that are present at birth. CHDs could be connected to sudden death (SD), defined by the WHO (World Health Organization) as "death occurring within 24 h after the onset of the symptoms" in an apparently "healthy" subject. These conditions can range from relatively mild defects to severe, life-threatening anomalies. The prevalence of CHDs varies across populations, but they affect millions of individuals worldwide. This article aims to discuss the post-mortem investigation of death related to CHDs, exploring the forensic approach, current methodologies, challenges, and potential advancements in this challenging field. A further goal of this article is to provide a guide for understanding these complex diseases, highlighting the pivotal role of autopsy, histopathology, and genetic investigations in defining the cause of death, and providing evidence about the translational use of autopsy reports. Forensic investigations play a crucial role in understanding the complexities of CHDs and determining the cause of death accurately. Through collaboration between medical professionals and forensic experts, meticulous examinations, and analysis of evidence, valuable insights can be gained. These insights not only provide closure to the families affected but also contribute to the prevention of future tragedies.

Variants of the promoter of MYH6 gene in congenital isolated and sporadic patent ductus arteriosus: case-control study and cellular functional analyses

Patent ductus arteriosus (PDA) is a common form of congenital heart disease. The MYH6 gene has important effects on cardiovascular growth and development, but the effect of variants in the MYH6 gene promoter on ductus arteriosus is unknown. DNA was extracted from blood samples of 721 subjects (428 patients with isolated and sporadic PDA and 293 healthy controls) and analyzed by sequencing for MYH6 gene promoter region variants. Cellular function experiments with three cell lines (HEK-293, HL-1, and H9C2 cells) and bioinformatics analyses were performed to verify their effects on gene expression. In the MYH6 gene promoter, 11 variants were identified. Four variants were found only in patients with PDA and 2 of them (g.3434G>C and g.4524C>T) were novel. Electrophoretic mobility shift assay showed that the transcription factors bound by the promoter variants were significantly altered in comparison to the wild-type in all three cell lines. Dual luciferase reporter showed that all the 4 variants reduced the transcriptional activity of the MYH6 gene promoter (P < 0.05). Prediction of transcription factors bound by the variants indicated that these variants alter the transcription factor binding sites. These pathological alterations most likely affect the contraction of the smooth muscle of ductus arteriosus, leading to PDA. This study is the first to focus on variants at the promoter region of the MYH6 gene in PDA patients with cellular function tests. Therefore, this study provides new insights to understand the genetic basis and facilitates further studies on the mechanism of PDA formation.

Identification of miR-20b-5p as an inhibitory regulator in cardiac differentiation via TET2 and DNA hydroxymethylation

BACKGROUND

Congenital heart disease (CHD) is a prevalent congenital cardiac malformation, which lacks effective early biological diagnosis and intervention. MicroRNAs, as epigenetic regulators of cardiac development, provide potential biomarkers for the diagnosis and treatment of CHD. However, the mechanisms underlying miRNAs-mediated regulation of cardiac development and CHD malformation remain to be further elucidated. This study aimed to explore the function of microRNA-20b-5p (miR-20b-5p) in cardiac development and CHD pathogenesis.

METHODS AND RESULTS

miRNA expression profiling identified that miR-20b-5p was significantly downregulated during a 12-day cardiac differentiation of human embryonic stem cells (hESCs), whereas it was markedly upregulated in plasma samples of atrial septal defect (ASD) patients. Our results further revealed that miR-20b-5p suppressed hESCs-derived cardiac differentiation by targeting tet methylcytosine dioxygenase 2 (TET2) and 5-hydroxymethylcytosine, leading to a reduction in key cardiac transcription factors including GATA4, NKX2.5, TBX5, MYH6 and cTnT. Additionally, knockdown of TET2 significantly inhibited cardiac differentiation, which could be partially restored by miR-20b-5p inhibition.

CONCLUSIONS

Collectively, this study provides compelling evidence that miR-20b-5p functions as an inhibitory regulator in hESCs-derived cardiac differentiation by targeting TET2, highlighting its potential as a biomarker for ASD.

Associations between NKX2-5 gene polymorphisms and congenital heart disease in the Chinese Tibetan population

BACKGROUND

The pathogenesis of congenital heart disease (CHD) has not been fully elucidated, and this study considers the interaction between inheritance and the environment as the main cause of CHD. Previous studies have found that the incidence of CHD in the Tibetan plateau population is significantly higher than in low-altitude populations. Numerous reports have confirmed that NKX2-5 gene mutations can lead to coronary heart disease, but the relationship between NKX2-5 and Tibetan nationality has not yet been reported.

OBJECTIVE

To explore the relationship between NKX2-5 gene polymorphisms and CHD in Tibetan people.

METHODS

Blood samples were collected retrospectively from Tibetan patients diagnosed with CHD as well as healthy Tibetans, and the exons of NKX2-5 were sequenced. The MassARRAY technique was used to detect and genotype candidate tag single nucleotide polymorphisms (SNPs) in the non-coding regions of NKX2-5.

RESULTS

Exon sequencing revealed no difference in the coding regions of the NKX2-5 gene between the CHD and control groups. In the non-coding regions of NKX2-5, rs6882776 and rs2546741 differed significantly between the two groups. Strong linkage disequilibrium was found between the selected sites of NKX2-5.

CONCLUSIONS

The NKX2-5 exons do not associate with CHD in Tibetans. Rs6882776 and rs2546741 in the non-coding regions of NKX2-5 may protect against CHD in Tibetans. The NKX2-5 haplotype associated with CHD occurrence in the Tibetan population.