Human Genetics of Defects of Situs.

Defects of situs are associated with complex sets of congenital heart defects in which the normal concordance of asymmetric thoracic and abdominal organs is disturbed. The cellular and molecular mechanisms underlying the formation of the embryonic left-right axis have been investigated extensively in the past decade. This has led to the identification of mutations in at least 33 different genes in humans with heterotaxy and situs defects. Those mutations affect a broad range of molecular components, from transcription factors, signaling molecules, and chromatin modifiers to ciliary proteins. A substantial overlap of these genes is observed with genes associated with other congenital heart diseases such as tetralogy of Fallot and double-outlet right ventricle, d-transposition of the great arteries, and atrioventricular septal defects. In this chapter, we present the broad genetic heterogeneity of situs defects including recent human genomics efforts.

Biallelic CRELD1 variants cause a multisystem syndrome, including neurodevelopmental phenotypes, cardiac dysrhythmias, and frequent infections.

PURPOSE: We sought to delineate a multisystem disorder caused by recessive cysteine-rich with epidermal growth factor-like domains 1 (CRELD1) gene variants. METHODS: The impact of CRELD1 variants was characterized through an international collaboration utilizing next-generation DNA sequencing, gene knockdown, and protein overexpression in Xenopus tropicalis, and in vitro analysis of patient immune cells. RESULTS: Biallelic variants in CRELD1 were found in 18 participants from 14 families. Affected individuals displayed an array of phenotypes involving developmental delay, early-onset epilepsy, and hypotonia, with about half demonstrating cardiac arrhythmias and some experiencing recurrent infections. Most harbored a frameshift in trans with a missense allele, with 1 recurrent variant, p.(Cys192Tyr), identified in 10 families. X tropicalis tadpoles with creld1 knockdown displayed developmental defects along with increased susceptibility to induced seizures compared with controls. Additionally, human CRELD1 harboring missense variants from affected individuals had reduced protein function, indicated by a diminished ability to induce craniofacial defects when overexpressed in X tropicalis. Finally, baseline analyses of peripheral blood mononuclear cells showed similar proportions of immune cell subtypes in patients compared with healthy donors. CONCLUSION: This patient cohort, combined with experimental data, provide evidence of a multisystem clinical syndrome mediated by recessive variants in CRELD1.

Genetic Alterations of Transcription Factors and Signaling Molecules Involved in the Development of Congenital Heart Defects-A Narrative Review.

Congenital heart defects (CHD) are the most common congenital abnormality, with an overall global birth prevalence of 9.41 per 1000 live births. The etiology of CHDs is complex and still poorly understood. Environmental factors account for about 10% of all cases, while the rest are likely explained by a genetic component that is still under intense research. Transcription factors and signaling molecules are promising candidates for studies regarding the genetic burden of CHDs. The present narrative review provides an overview of the current knowledge regarding some of the genetic mechanisms involved in the embryological development of the cardiovascular system. In addition, we reviewed the association between the genetic variation in transcription factors and signaling molecules involved in heart development, including TBX5, GATA4, NKX2-5 and CRELD1, and congenital heart defects, providing insight into the complex pathogenesis of this heterogeneous group of diseases. Further research is needed in order to uncover their downstream targets and the complex network of interactions with non-genetic risk factors for a better molecular-phenotype correlation.

Polymorphisms of CRELD1 and DNAJC30 and their relationship with chicken carcass traits.

Carcass traits play important roles in the broiler industry and single nucleotide polymorphism (SNP) can be efficient molecular markers for marker-assisted breeding of chicken carcass traits. Based on our previous RNA-seq data (accession number GSE58755), cysteine rich with epidermal growth factor like domains 1 (CRELD1) and DnaJ heat shock protein family member C30 (DNAJC30) are differentially expressed in breast muscle between white recessive rock chicken (WRR) and Xinghua chicken (XH). In this study, we further characterize the potential function and SNP mutation of CRELD1 and DNAJC30 in chicken for the first time. According to protein interaction network and enrichment analysis, CRELD1 and DNAJC30 may play some roles in chicken muscle development and fat deposition. In WRR and XH, the results of the relative tissue expression pattern demonstrated that CRELD1 and DNAJC30 are not only differentially expressed in breast muscle but also leg muscle and abdominal fat. Therefore, we identified 5 SNP sites of CRELD1 and 7 SNP sites of DNAJC30 and genotyped them in an F2 chicken population. There are 4 sites of CRELD1 and 3 sites of DNAJC30 are associated with chicken carcass traits like breast muscle weight, body weight, dressed weight, leg weight percentage, eviscerated weight with giblet percentage, intermuscular adipose width, shank length, and girth. These results suggest that the SNP sites of CRELD1 and DNAJC30 can be potential molecular markers to improve the chicken carcass traits and lay the foundation for marker-assisted selection.

Creld1 regulates myocardial development and function.

CRELD1 (Cysteine-Rich with EGF-Like Domains 1) is a risk gene for non-syndromic atrioventricular septal defects in human patients. In a mouse model, Creld1 has been shown to be essential for heart development, particularly in septum and valve formation. However, due to the embryonic lethality of global Creld1 knockout (KO) mice, its cell type-specific function during peri- and postnatal stages remains unknown. Here, we generated conditional Creld1 KO mice lacking Creld1 either in the endocardium (KOTie2) or the myocardium (KOMyHC). Using a combination of cardiac phenotyping, histology, immunohistochemistry, RNA-sequencing, and flow cytometry, we demonstrate that Creld1 function in the endocardium is dispensable for heart development. Lack of myocardial Creld1 causes extracellular matrix remodeling and trabeculation defects by modulation of the Notch1 signaling pathway. Hence, KOMyHC mice die early postnatally due to myocardial hypoplasia. Our results reveal that Creld1 not only controls the formation of septa and valves at an early stage during heart development, but also cardiac maturation and function at a later stage. These findings underline the central role of Creld1 in mammalian heart development and function.

The effect of CRELD1 gene on the related genes in endocardial cushion development / 中华实用儿科临床杂志

Objective To investigate the effect of alteration of CRELD1 gene expression on the related genes in the endocardial cushion development.Methods Over-expression and silence of CRELD1 gene were realized by the construction of lentiviral vector.Afterwards,the lentiviral vectors were used to infect the human fetal lung fibroblasts (HFL)-I.All of the cells were divided into the following 5 groups:the blank control group,the negative control group of interference,the interference group,the negative control group of over-expression,and the over-expression group.Western blot and real-time fluorescent quantitative polymerase chain reaction were applied to examine the mRNA and protein expression of CRELD1,Sox9,Aggrecan,Scleraxis and Tenascin-C.Results The DNA sequences of 2 recombinant plasmids pLV3-shRNA-CRELD1 and pLV4-CRELD1 matched very well with those which were designed according to the DNA sequence analysis.HFL-I was successfully infected with lentiviral vectors and displayed fluorescent green light under inverted fluorescence microscope.The results of real-time PCR detection and Western blot test were consistent:expressions of Sox9 and Aggrecan in the interference group were significantly higher than those in the negative control group of interference,while the expressions of the 2 genes in the over-expression group were significantly lower than those in the negative control group of over-expression.Expressions of Scleraxis increased in both the interference group and the over-expression group when compared with the negative control groups respectively.Compared to the corresponding negative control groups,Tenascin-C expression decreased markedly in the interference group,whereas it increased significantly in over-expression group.Conclusions CRELD1 gene has negative effect on the expression of the related genes Sox9 and Aggrecan in the endocardial cushion development,whereas it has positive effect on the Tenascin-C expression.It serves as a theoretical framework to illustrate the effect of CRELD1 gene on the atrioventricular septal defect.

Genetics progress on atrioventricular septal defect / 国际儿科学杂志

Atrioventricular septal defect (AVSD) is a common cardiovascular malformation because of atrioventricular septal (lower atrial septum, ventricular septal upper) and the endocardial cushion defect,resulting in abnormal chambers of the heart. At the present, although the embryology, pathophysiology,diagnosis and treatment of the AVSD are clarified, but its precise pathogenesis has still no breakthrough progress.With the wide application of molecular biology and the depth research of molecular genetics, a series of new progress about AVSD has been made in the genetic study, and some genes are confirmed to be related to the occurrence and development of AVSD. The aim of this article is to review and discuss genetic mechanisms and related genes of AVSD, and to further identify the major genes causing AVSD.