De novo 9q gain in an infant with tetralogy of Fallot with absent pulmonary valve: Patient report and review of congenital heart disease in 9q duplication syndrome

Next Generation Sequencing Identify Rare Copy Number Variants in Non-syndromic Patent Ductus Arteriosus

Patent ductus arteriosus (PDA) is a common congenital cardiovascular malformation with both inherited and acquired causes. Several genes have been reported to be related to PDA, but the molecular pathogenesis is still unclear. Here, we screened a population matched cohort of 39 patients with PDA and 100 healthy children using whole exome sequencing (WES). And identified 10 copy number variants (CNVs) and 20 candidate genes using Gene ontology (GO) functional enrichment analysis. In gene network analysis, we screened 7 pathogenic CNVs of 10 candidate genes (MAP3K1, MYC, VAV2, WDR5, RXRA, APLNR, TJP1, ERCC2, FOSB, CHRNA4). Further analysis of transcriptome array showed that 7 candidate genes (MAP3K1, MYC, VAV2, APLNR, TJP1, FOSB, CHRNA4) were indeed significantly expressed in human embryonic heart. Moreover, CHRNA4 was observed the most important genes. Our data provided rare CNVs as potential genetic cause of PDA in humans and also advance understanding of the genetic components of PDA.

9q34 & 16p13 chromosome duplications in autism

Epigenetic mechanisms, genetic factors, and environment influence the diversity of phenotypes developed in various diseases. Duplications in several chromosomes are well characterized in the scientific literature, but partial duplications, in some cases, present with milder forms of a disease and are yet to be understood. Fortunately, the identification of genetic diseases has now become more feasible due to several cytogenetic techniques such as microarray analysis and karyotyping. With these tools, together with other laboratory results and clinical examination, we are able to report the first case in the medical literature of double partial trisomy of chromosome 9q34 and 16p13.

Congenital heart diseases: genetics, non-inherited risk factors, and signaling pathways

Background

Congenital heart diseases (CHDs) are the most common congenital anomalies with an estimated prevalence of 8 in 1000 live births. CHDs occur as a result of abnormal embryogenesis of the heart. Congenital heart diseases are associated with significant mortality and morbidity. The damage of the heart is irreversible due to a lack of regeneration potential, and usually, the patients may require surgical intervention. Studying the developmental biology of the heart is essential not only in understanding the mechanisms and pathogenesis of congenital heart diseases but also in providing us with insight towards developing new preventive and treatment methods.

Main body

The etiology of congenital heart diseases is still elusive. Both genetic and environmental factors have been implicated to play a role in the pathogenesis of the diseases. Recently, cardiac transcription factors, cardiac-specific genes, and signaling pathways, which are responsible for early cardiac morphogenesis have been extensively studied in both human and animal experiments but leave much to be desired. The discovery of novel genetic methods such as next generation sequencing and chromosomal microarrays have led to further study the genes, non-coding RNAs and subtle chromosomal changes, elucidating their implications to the etiology of congenital heart diseases. Studies have also implicated non-hereditary risk factors such as rubella infection, teratogens, maternal age, diabetes mellitus, and abnormal hemodynamics in causing CHDs.

These etiological factors raise questions on multifactorial etiology of CHDs. It is therefore important to endeavor in research based on finding the causes of CHDs. Finding causative factors will enable us to plan intervention strategies and mitigate the consequences associated with CHDs. This review, therefore, puts forward the genetic and non-genetic causes of congenital heart diseases. Besides, it discusses crucial signaling pathways which are involved in early cardiac morphogenesis. Consequently, we aim to consolidate our knowledge on multifactorial causes of CHDs so as to pave a way for further research regarding CHDs.

Conclusion

The multifactorial etiology of congenital heart diseases gives us a challenge to explicitly establishing specific causative factors and therefore plan intervention strategies. More well-designed studies and the use of novel genetic technologies could be the way through the discovery of etiological factors implicated in the pathogenesis of congenital heart diseases.

Utility of chromosomal microarray for diagnosis in cases of nonimmune hydrops fetalis

PURPOSE

Chromosomal microarray (CMA) is recommended in the diagnostic evaluation of cases with fetal structural anomalies when invasive testing is pursued. However, the utility of CMA for nonimmune hydrops fetalis (NIHF) specifically is not well known. Our objective was to describe the overall yield of CMA in the diagnostic evaluation of NIHF, comparing isolated cases to those with concurrent structural anomalies.

METHODS

This was a retrospective cohort study of all prenatally diagnosed NIHF cases evaluated at the University of California, San Francisco from 2008 to 2018. NIHF due to twin-twin transfusion syndrome was excluded.

RESULTS

There were 131 cases of prenatally diagnosed NIHF. In 43/44 cases with a CMA performed, results were categorized as normal or likely benign. One case was found on CMA to have a large pathogenic duplication of 21p11.2q22.3, which could have been detected by karyotype and was consistent with a diagnosis of Down syndrome. There was no incremental yield demonstrated for CMA over karyotype.

CONCLUSIONS

Among a cohort of prenatally diagnosed NIHF cases, CMA did not identify any copy number variants beyond those detectable by karyotype, and the vast majority of CMAs were normal. These results suggest that CMA has low diagnostic utility for NIHF.

A system-based approach to the genetic etiologies of non-immune hydrops fetalis

A wide spectrum of genetic causes may lead to nonimmune hydrops fetalis (NIHF), and a thorough phenotypic and genetic evaluation are essential to determine the underlying etiology, optimally manage these pregnancies, and inform discussions about anticipated prognosis. In this review, we outline the known genetic etiologies of NIHF by fetal organ system affected, and provide a systematic approach to the evaluation of NIHF. Some of the underlying genetic disorders are associated with characteristic phenotypic features that may be seen on prenatal ultrasound, such as hepatomegaly with lysosomal storage disorders, hyperechoic kidneys with congenital nephrosis, or pulmonary valve stenosis with RASopathies. However, this is not always the case, and the approach to evaluation must include prenatal ultrasound findings as well as genetic testing and many other factors. Genetic testing that has been utilized for NIHF ranges from standard chromosomal microarray or karyotype to gene panels and broad approaches such as whole exome sequencing. Family and obstetric history, as well as pathology examination, can yield additional clues that are helpful in establishing a diagnosis. A systematic approach to evaluation can guide a more targeted approach to genetic evaluation, diagnosis, and management of NIHF.

A patient with Phelan-McDermid syndrome and dilation of the great vessels

We present a patient with Phelan-McDermid syndrome, a rare neurodevelopmental disorder caused by a 22q13 deletion, with the previously undescribed finding of progressive dilation of the great arteries. While congenital heart defects have been identified in patients previously, dilation of the great arteries has not been described to our knowledge.

Results of next-generation sequencing gene panel diagnostics including copy-number variation analysis in 810 patients suspected of heritable thoracic aortic disorders

Simultaneous analysis of multiple genes using next-generation sequencing (NGS) technology has become widely available. Copy-number variations (CNVs) in disease-associated genes have emerged as a cause for several hereditary disorders. CNVs are, however, not routinely detected using NGS analysis. The aim of this study was to assess the diagnostic yield and the prevalence of CNVs using our panel of Hereditary Thoracic Aortic Disease (H-TAD)-associated genes. Eight hundred ten patients suspected of H-TAD were analyzed by targeted NGS analysis of 21 H-TAD associated genes. In addition, the eXome hidden Markov model (XHMM; an algorithm to identify CNVs in targeted NGS data) was used to detect CNVs in these genes. A pathogenic or likely pathogenic variant was found in 66 of 810 patients (8.1%). Of these 66 pathogenic or likely pathogenic variants, six (9.1%) were CNVs not detectable by routine NGS analysis. These CNVs were four intragenic (multi-)exon deletions in MYLK, TGFB2, SMAD3, and PRKG1, respectively. In addition, a large duplication including NOTCH1 and a large deletion encompassing SCARF2 were detected. As confirmed by additional analyses, both CNVs indicated larger chromosomal abnormalities, which could explain the phenotype in both patients. Given the clinical relevance of the identification of a genetic cause, CNV analysis using a method such as XHMM should be incorporated into the clinical diagnostic care for H-TAD patients.

Whole exome sequencing identifies novel mutation in eight Chinese children with isolated tetralogy of Fallot

Background

Tetralogy of Fallot is the most common cyanotic congenital heart disease. However, its pathogenesis remains to be clarified. The purpose of this study was to identify the genetic variants in Tetralogy of Fallot by whole exome sequencing.

Methods

Whole exome sequencing was performed among eight small families with Tetralogy of Fallot. Differential single nucleotide polymorphisms and small InDels were found by alignment within families and between families and then were verified by Sanger sequencing. Tetralogy of Fallot-related genes were determined by analysis using Gene Ontology /pathway, Online Mendelian Inheritance in Man, PubMed and other databases.

Results

A total of sixteen differential single nucleotide polymorphisms loci and eight differential small InDels were discovered. The sixteen differential single nucleotide polymorphisms loci were located on Chr 1, 2, 4, 5, 11, 12, 15, 22 and X. Among the sixteen single nucleotide polymorphisms loci, six has not been reported. The eight differential small InDels were located on Chr 2, 4, 9, 12, 17, 19 and X, whereas of the eight differential small InDels, two has not been reported. Analysis using Gene Ontology /pathway, Online Mendelian Inheritance in Man, PubMed and other databases revealed that PEX5, NACA, ATXN2, CELA1, PCDHB4 and CTBP1 were associated with Tetralogy of Fallot.

Conclusions

Our findings identify PEX5, NACA, ATXN2, CELA1, PCDHB4 and CTBP1 mutations as underlying genetic causes of isolated tetralogy of Fallot.

Familial 9q33q34 microduplication in siblings with developmental disorders and macrocephaly

Because several genes responsible for epileptic encephalopathy are located on the 9q33q34 region, patients with chromosomal deletions of this region often show intractable epilepsy and neurodevelopmental disability. Contrary to these findings, chromosomal duplications of this region have never been reported previously. We identified a first case of 9q33q34 microduplications in siblings associated with developmental disorders and macrocephaly. Their mother was a mosaic carrier of this duplication. Duplicated regions involved STXBP1; the gene related to epileptic encephalopathy. Neurological features including developmental delay and macrocephaly observed in the present siblings may be derived from the extra-copy of STXBP1.

Clinical and genomic evaluation of a Chinese patient with a novel deletion associated with Phelan-McDermid syndrome

Phelan–McDermid syndrome is a neurodevelopmental disorder caused by the terminal deletion of chromosome 22 (22q13) followed by the loss of function of the SHANK3 gene. Various terminal deletions of chromosome 22q13 are associated with Phelan–McDermid with a spectrum of phenotypic severity. Here, we have done a clinical molecular study of a Chinese proband with Phelan–McDermid syndrome. Both the proband and her younger brother are associated with this syndrome while their parents are phenotypically normal. We used a karyotype in order to detect the genotype of the proband and her younger brother. We have also used whole genome low-coverage paired-end next generation sequencing to determine whether the parent is the carrier of translocation with terminal 22q13 deletions. We found that both proband and her younger brother are comprises of a novel deletion of 22q13.31q13.33, harboring genes were associated with several clinical phenotype such as severity of speech delay, neonatal hypotonia, delayed in age of walking, male genital anomalies, dysplastic toenails, large and fleshy hands, macrocephaly, short stature, facial asymmetry, and atypical reflexes. Probands and her younger brother inherited this translocation from their mother whereas their father is genotypically normal. In conclusion, our present study expands the deletion spectrum and report a novel deletion associated with Phelan–McDermid syndrome.

Prediction and validation of protein-protein interactors from genome-wide DNA-binding data using a knowledge-based machine-learning approach

The ability to accurately predict the DNA targets and interacting cofactors of transcriptional regulators from genome-wide data can significantly advance our understanding of gene regulatory networks. NKX2-5 is a homeodomain transcription factor that sits high in the cardiac gene regulatory network and is essential for normal heart development. We previously identified genomic targets for NKX2-5 in mouse HL-1 atrial cardiomyocytes using DNA-adenine methyltransferase identification (DamID). Here, we apply machine learning algorithms and propose a knowledge-based feature selection method for predicting NKX2-5 protein : protein interactions based on motif grammar in genome-wide DNA-binding data. We assessed model performance using leave-one-out cross-validation and a completely independent DamID experiment performed with replicates. In addition to identifying previously described NKX2-5-interacting proteins, including GATA, HAND and TBX family members, a number of novel interactors were identified, with direct protein : protein interactions between NKX2-5 and retinoid X receptor (RXR), paired-related homeobox (PRRX) and Ikaros zinc fingers (IKZF) validated using the yeast two-hybrid assay. We also found that the interaction of RXRα with NKX2-5 mutations found in congenital heart disease (Q187H, R189G and R190H) was altered. These findings highlight an intuitive approach to accessing protein-protein interaction information of transcription factors in DNA-binding experiments.

A de novo duplication of chromosome 9q34.13-qter in a fetus with Tetralogy of Fallot Syndrome

Background

Partial duplications of the distal 9q have been rarely reported in literatures. The key features included characteristic facial appearance, long fingers and toes, slight psychomotor retardation, heart murmur et al. But rare severe congenital heart defects (CHD) such as TOF were reported to be associated with 9qter duplications.

Case presentation

A 23-year-old woman was referred for genetic counseling and prenatal diagnosis at 25^3/7 weeks of gestation due to her male fetus, diagnosed as Tetralogy of Fallot Syndrome (TOF) by prenatal ultrasound. SNP (Single nucleotide polymorphism) array revealed that the male fetus had a de novo 5.47 Mb duplication at 9q34.13-qter. Meanwhile, non-invasive prenatal testing (NIPT) using low coverage whole genome massively parallel sequencing of circulating cell-free fetal DNA (cffDNA) showed consistent results. Multiplex ligation-dependent probe amplification (MLPA) also confirmed the duplication at 9qter.

Conclusion

In this paper, we present an Asian fetus with TOF caused by a de novo 5.47 Mb duplication at 9q34.13-qter. Duplication of 9q34.13-qter should be considered as an etiological diagnosis in the case of TOF. Our prenatal diagnostic findings provide important information for genetic counseling on the male fetus and future pregnancies in this family. Chromosomal microarray analysis (CMA) remains the first-tier clinical diagnostic test for prenatal fetus with suspicious syndromes. We also highlight the high potential application of NIPT in the screening of sub-chromosomal rearrangement.