Analysis of the CHD7 gene mutations in patients of congenital heart disease with extracardiac malformations.

Background: Congenital heart disease (CHD) is a common birth defect, and is frequently accompanied with extracardiac malformations (ECM). Uncovering the genetic etiology of CHD may have a meaningful impact on disease management. De novo variants have been proven to be associated with CHD. Methods: Whole exome sequencing was performed for 4 unrelated CHD families with extracardiac malformations, candidate genes were screened by using stringent bioinformatics analysis, and the obtained variants were confirmed by Sanger sequencing. RT-PCR and Sanger sequencing were used to investigate the influence of a splice variant on pre-mRNA splicing. Further targeted sequencing was conducted to investigate the association of CHD7 variants with sporadic CHD. Results: Four novel heterozygous loss-of-function CHD7 mutations were found by using stringent bioinformatics analysis: the frameshift mutation c.1951_1952delAAinsT (p.L651X) in family #1, the nonsense mutations c.2913C>G (p.Y971X) in family #2 and c.3106C>T (pA1036X) in family #3, and the splicing mutation c.4353+4_4353+12delinsGCCCA in family #4. Sanger sequencing confirmed that these were all de novo mutations and were absent in the healthy parents and siblings of the probands. Further studies revealed that the splice mutation c.4353+4_4353+12delinsGCCCA influenced CHD7 mRNA splicing in vivo. Targeted sequencing found 23 rare mutations in 1,155 sporadic CHD patients. Conclusions: The findings here confirm that de novo loss-of-function variants of the CHD7 gene are the genetic cause of familial CHD with extracardiac malformations and the spectrum of pathogenic CHD7 variants in sporadic CHD is expanded.

Clinical characteristics and mortality risk prediction model in children with acute myocarditis.

BACKGROUND: Acute myocarditis (AMC) can cause poor outcomes or even death in children. We aimed to identify AMC risk factors and create a mortality prediction model for AMC in children at hospital admission. METHODS: This was a single-center retrospective cohort study of AMC children hospitalized between January 2016 and January 2020. The demographics, clinical examinations, types of AMC, and laboratory results were collected at hospital admission. In-hospital survival or death was documented. Clinical characteristics associated with death were evaluated. RESULTS: Among 67 children, 51 survived, and 16 died. The most common symptom was digestive disorder (67.2%). Based on the Bayesian model averaging and Hosmer-Lemeshow test, we created a final best mortality prediction model (acute myocarditis death risk score, AMCDRS) that included ten variables (male sex, fever, congestive heart failure, left-ventricular ejection fraction < 50%, pulmonary edema, ventricular tachycardia, lactic acid value > 4, fulminant myocarditis, abnormal creatine kinase-MB, and hypotension). Despite differences in the characteristics of the validation cohort, the model discrimination was only marginally lower, with an AUC of 0.781 (95% confidence interval = 0.675-0.852) compared with the derivation cohort. Model calibration likewise indicated acceptable fit (Hosmer‒Lemeshow goodness-of-fit, P» = 0.10). CONCLUSIONS: Multiple factors were associated with increased mortality in children with AMC. The prediction model AMCDRS might be used at hospital admission to accurately identify AMC in children who are at an increased risk of death.

An X-linked PLXNB3 mutation identified in patients with congenital heart disease with neurodevelopmental disabilities.

Background: Congenital heart disease (CHD) is the most common birth defect and is often accompanied by neurodevelopmental disabilities (NDD) which increase the associated mortality. Plexin families are known to play a key role in the development of heart and the occurrence of neurodevelopmental anomalies. However, there has been no report of PLXNB3 mutation in isolated CHD or CHD with concomitant NDD. Methods: We performed whole-exome sequencing (WES) on a proband with CHD with neurodevelopmental anomalies and his family members. Targeted sequencing, conservation analysis, AlphaFold, and PyRosetta were performed to identify more pathogenic mutations of PLXNB3. Scratch wound assay, Ki-67 assessment by flow cytometry, and gene expression analysis of heart development related pathway by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were conducted after 24 h transfection in AC16 and HEK293T to investigate the effect of the target mutation. Results: We identified a pathogenic mutation in the X-linked PLXNB3 gene (c.A4319T p.E1440V). In addition, we found 4 other pathogenic mutations in a cohort of 75 patients with sporadic CHD with NDD. AlphaFold and PyRosetta predicted that these 4 mutations could cause dramatic changes of the PLXNB3 protein structure (root-mean-square deviation score >10 Å). Further functional analysis revealed that this p.E1440V variant inhibits cell migration and proliferation, and affects the activity of key factors in the Notch signaling pathway, myocardial contraction pathway, and neurodevelopmental pathways. Conclusions: These findings suggest that PLXNB3 and the p.E1440V variant may be related to the pathogenesis of CHD associated with NDD.