Computed Fluid Dynamics Analysis for SVC-to-RPA Anastomosis With Antegrade Pulmonary Flow.

We report an infant case after superior vena cava -to-right pulmonary artery anastomosis with antegrade pulmonary flow in which computational fluid dynamics analysis showed that restriction of antegrade blood flow by the remaining right pulmonary stenosis resulted in reduced shear stress and energy loss in the superior vena cava.

The c.1617del variant of TMEM260 is identified as the most frequent single gene determinant for Japanese patients with a specific type of congenital heart disease.

Although the molecular mechanisms underlying congenital heart disease (CHD) remain poorly understood, recent advances in genetic analysis have facilitated the exploration of causative genes for CHD. We reported that the pathogenic variant c.1617del of TMEM260, which encodes a transmembrane protein, is highly associated with CHD, specifically persistent truncus arteriosus (PTA), the most severe cardiac outflow tract (OFT) defect. Using whole-exome sequencing, the c.1617del variant was identified in two siblings with PTA in a Japanese family and in three of the 26 DNAs obtained from Japanese individuals with PTA. The c.1617del of TMEM260 has been found only in East Asians, especially Japanese and Korean populations, and the frequency of this variant in PTA is estimated to be next to that of the 22q11.2 deletion, the most well-known genetic cause of PTA. Phenotype of patients with c.1617del appears to be predominantly in the heart, although TMEM260 is responsible for structural heart defects and renal anomalies syndrome (SHDRA). The mouse TMEM260 variant (p.W535Cfs*56), synonymous with the human variant (p.W539Cfs*9), exhibited truncation and downregulation by western blotting, and aggregation by immunocytochemistry. In situ hybridization demonstrated that Tmem260 is expressed ubiquitously during embryogenesis, including in the development of cardiac OFT implicated in PTA. This expression may be regulated by a ~ 0.8 kb genomic region in intron 3 of Tmem260 that includes multiple highly conserved binding sites for essential cardiac transcription factors, thus revealing that the c.1617del variant of TMEM260 is the major single-gene variant responsible for PTA in the Japanese population.

A genetic and developmental biological approach for a family with complex congenital heart diseases-evidence of digenic inheritance.

Objective: Congenital heart disease (CHD) is caused by cardiovascular developmental defects and has a global prevalence of ∼1%. The etiology of CHD is multifactorial and remains generally unknown, despite advances in analytical techniques based on next-generation sequencing (NGS). The aim of our study was to elucidate the multi-genetic origin and pathogenesis of an intriguing familial case with complex CHD. Methods: We performed an original trio-based gene panel analysis using NGS of the family, including two siblings with CHD of single ventricular phenotype, and their unaffected parents. The pathogenicity of the detected rare variants was investigated in silico, and the functional effects of the variants were confirmed in vitro using luciferase assays. The combinatorial effect of gene alterations of the putative responsible genes was tested in vivo using genetically engineered mutant mice. Results: NGS-based gene panel analyses revealed two heterozygous rare variants in NODAL and in TBX20 common to the siblings and to just one of parents. Both variants were suspected pathogenic in silico, and decreased transcriptional activities of downstream signaling pathways were observed in vitro. The analyses of Nodal and Tbx20 double mutant mice demonstrated that Nodal+/-Tbx20-/- embryos showed more severe defects than Nodal+/+Tbx20-/- embryos during early heart development. The expression of Pitx2, a known downstream target of Nodal, was downregulated in Tbx20-/- mutants. Conclusions: Two rare variants on NODAL and TBX20 genes detected in this family were considered to be loss-of-function mutations. Our results suggest that NODAL and TBX20 may be complementary for the cardiac development, and a combinatorial loss-of-function of NODAL and TBX20 could be implicated in digenic inherence as the etiology of complex CHD associated with single ventricle defects in this family.

Clinical Characteristics of Coronary-to-Pulmonary Artery Fistula in Patients with Pulmonary Atresia and Ventricular Septal Defect.

The existence of a coronary-to-pulmonary artery fistula (CPF) in pulmonary atresia with ventricular septal defect (PAVSD) potentially affects treatment; however, its clinical features have not been comprehensively described due to the disease's rarity. We reviewed 69 cases from 42 studies to reveal the clinical overview of patients with CPF and PAVSD. Among the included patients, the male-to-female ratio was exactly 1:1, and only two patients (3%) exhibited the 22q11.2 microdeletion syndrome. Regarding anatomical features, CPFs originated from the left coronary artery in 65% of patients, and 62% had other major aortopulmonary collateral arteries. Thirty-nine percent of patients had a definitive CPF diagnosis at 0 years of age, whereas 10% were diagnosed in adulthood. Seventy percent underwent catheter angiography to obtain a definitive CPF diagnosis. Ninety-five percent of patients underwent cardiac surgery, and among them, 43% underwent palliative surgery, whereas 52% underwent one-stage repair. Four patients including three adult patients developed cardiac dysfunction due to myocardial ischemia, and three of them exhibited improved cardiac function after the intervention for CPF. Of all the patients, 88% survived and 12% died. The surgical strategy and prognosis were similar to those in PAVSD patients without CPF. This review provides detailed clinical phenotypes that are potentially useful in enhancing the management of patients with this rare disease.

Association of Type 2 Deiodinase Thr92Ala Polymorphism with Pediatric Obesity in Japanese Children: A Case-Control Study.

Genetic factors play critical roles in the onset and progression of obesity. Brown adipose tissue (BAT) activity is also critical for adiposity. The objective of this study was to evaluate the prevalence and effects of BAT gene polymorphisms in pediatric obesity. This case-control study included 270 non-obese and 86 obese children. All participants underwent genotyping for type 2 deiodinase (DIO2) Thr92Ala (rs225014). The prevalence of the homozygous Ala/Ala allele of the DIO2 gene in the obese group was 15.1% versus 6.3% in the non-obese group, resulting in an odds ratio (OR) of 3.393 (p = 0.003). The results of this study indicate that the homozygous Ala/Ala allele of the DIO2 gene is associated with an increased risk of pediatric obesity and suggest that pediatric obesity might be suitable for assessing the association with gene polymorphisms related to BAT, especially DIO2 Thr92Ala.

Successful Preoperative Partial Splenic Artery and Aneurysm Embolization for Thrombocytopenia Associated with Failed Fontan Circulation.

Long-term complications after the Fontan procedure are important concerns for patients with pediatric and adult congenital heart disease. Although thrombocytopenia due to portal hypertension and hypersplenism is a well-known complication of the Fontan circulation, few studies have reported on its management. Herein we describe a young adult Fontan patient with thrombocytopenia and a splenic artery aneurysm caused by conduit stenosis. The patient required conduit replacement due to high venous pressure. We performed partial splenic artery embolization (PSE) and embolization of the aneurysm preoperatively to reduce the risk of bleeding, resulting in successful subsequent cardiac surgery. Preoperative evaluation of the splenic artery aneurysm was informative, and PSE was a safe and effective treatment option for thrombocytopenia to avoid bleeding during open-heart surgery in this patient.

Genetic and functional analyses of TBX4 reveal novel mechanisms underlying pulmonary arterial hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a fatal disease, with approximately 10% of cases associated with genetic variants. Recent genetic studies have reported pathogenic variants in the TBX4 gene in patients with PAH, especially in patients with childhood-onset of the disease, but the pathogenesis of PAH caused by TBX4 variant has not been fully uncovered. METHODS: We analysed the TBX4 gene in 75 Japanese patients with sporadic or familial PAH using a PCR-based bidirectional sequencing method. Detected variants were evaluated using in silico analyses as well as in vitro analyses including luciferase assay, immunocytochemistry and chromatin immunoprecipitation (ChIP) whether they have altered function. We also analysed the function of TBX4 using mouse embryonic lung explants with inhibition of Tbx4 expression. RESULTS: Putative pathogenic variants were detected in three cases (4.0%). Our in vitro functional analyses revealed that TBX4 directly regulates the transcriptional activity of fibroblast growth factor 10 (FGF10), whereas the identified TBX4 variant proteins failed to activate the FGF10 gene because of disruption of nuclear localisation signal or poor DNA-binding affinity. Furthermore, ex vivo inhibition of Tbx4 resulted in insufficiency of lung morphogenesis along with specific downregulation of Tie2 and Kruppel-like factor 4 expression. CONCLUSION: Our results implicate variants in TBX4 as a genetic cause of PAH in a subset of the Japanese population. Variants in TBX4 may lead to PAH through insufficient lung morphogenesis by disrupting the TBX4-mediated direct regulation of FGF10 signalling and pulmonary vascular endothelial dysfunction involving PAH-related molecules.

Case Report: COVID-19 Pandemic Exacerbates Eating Disorder by Social and Intrafamilial Isolation.

The coronavirus disease-2019 (COVID-19) pandemic has increased the stress levels of children and their parents and diagnoses of eating disorders (EDs), irritable bowel syndrome, migraines, tension headaches, orthostatic dysregulation, and/or school refusal has increased among children. We present a case of a nine-year old girl, which rapidly worsened due to stress and isolation related to the COVID-19 pandemic. The patient's father noted her rapid weight loss due to poor oral intake. While she had already stopped gaining weight before the pandemic, her weight rapidly decreased to 22 kg during the pandemic. We diagnosed her with an ED and administrated nasogastric tube feeding. We postulated that not only social isolation, but also the disruption in her relationship with her parents, due to the pandemic, contributed to her ED. During a family meeting, she revealed that she felt more anxious during the pandemic. After the meeting, her parents rescheduled their jobs so that the family can have dinner together every night. The patient started eating sufficiently and weighed 31.8 kg at the one-year follow-up. The proportion of children with ED increased during the pandemic; their symptoms worsened because they felt lonely due to social and intrafamilial isolation. While parents have themselves experienced more stress during the pandemic, children, including those with ED, have experienced increased stress related directly to the pandemic, as well as indirectly from their parents. Pediatricians should consider the impact of stress on children, especially from social and intrafamilial isolation, both during and after the pandemic.

A Case of Type 2 Diabetes Mellitus With t(6;7)(q24;q31.2) Balanced Translocation.

Most balanced translocations do not involve any gain or loss of genetic material, and individuals harboring these translocations remain clinically asymptomatic. Nevertheless, balanced translocations have reportedly been associated with several diseases. Here, we present the case of a 12-year-old boy with type 2 diabetes mellitus that could not be explained only by obesity; the patient harbored a balanced translocation (46,XY t(6;7)(q24;q31.2)). Interestingly, genetic analysis showed that his 10-year-old sister also carried the same translocation and shared the same symptoms. Further analyses are required to confirm whether this balanced translocation is associated with the symptoms presented in our patient and his sibling. The outcomes of our case study are expected to reveal novel loci causing diabetes and have implications for improved diagnosis and treatment.

A Case of Infantile Alagille Syndrome With Severe Dyslipidemia: New Insight into Lipid Metabolism and Therapeutics.

Alagille syndrome (AGS) is an autosomal dominant genetic disorder characterized by congenital heart disease, hepatic cholestasis, dyslipidemia, and characteristic facies since infancy. Cholestatic hypercholesterolemia in patients diagnosed with AGS is occasionally refractory and resistant to conventional treatments. We report the case of a 4-month-old boy diagnosed with AGS and refractory dyslipidemia due to cholestatic liver disease. He had repeated episodes of cyanosis due to pulmonary artery atresia since birth and underwent a Blalock-Taussig shunt procedure at age 3 months. At age 4 months, cholestatic hyperbilirubinemia deteriorated to a serum total bilirubin level of 19.9 mg/dL. At age 12 months, a laboratory test revealed severe dyslipidemia (serum total cholesterol, 1796 mg/dL; serum triglycerides [TGs], 635 mg/dL), and the presence of xanthomas. A pathogenic variant of the JAG1 gene (c.1326G > A, p.Trp442X) was detected through genetic testing. Oral ursodeoxycholate normalized hyperbilirubinemia with a subtle improvement in dyslipidemia. Combination therapy with pravastatin and fenofibrate did not successfully improve dyslipidemia. At age 20 months, altering pravastatin to atorvastatin was effective in normalizing serum cholesterol and TGs with no adverse events. Combination therapy with atorvastatin and fenofibrate was successful in improving refractory dyslipidemia in a child with AGS. Atorvastatin is a well-known strong statin that can lower serum cholesterol, and fenofibrate can lower serum TG levels. We propose that atorvastatin be taken into consideration for the treatment of persistent hyperlipidemia in patients diagnosed with AGS, because atorvastatin upregulates bile acid synthesis and lipoprotein scavenging, and inhibits intrinsic cholesterol production.

Echocardiographic Left Ventricular Z-Score Utility in Predicting Pulmonary-Systemic Flow Ratio in Children With Ventricular Septal Defect or Patent Ductus Arteriosus.

BACKGROUND: The correlation between the Z-score of the left ventricular (LV) diameter and the LV volume-overload due to pulmonary over-circulation in children with ventricular septal defect (VSD) or patent ductus arteriosus (PDA) remains unclear.Methods and Results:The present, retrospective study enrolled 70 children (aged 0.3-16.8 years; 33 males, 37 females) with a diagnosis of isolated VSD and/or PDA who underwent cardiac catheterization (CC) between 2015 and 2019. Patients with chromosomal/genetic anomalies, growth disorder, right-ventricular enlargement or other conditions causing LV enlargement were excluded. Echocardiographic parameters were retrospectively evaluated from the medical records, converted to a Z-score, then compared with CC data. The pulmonary-systemic flow ratio on CC (cQp/Qs) correlated significantly with the Z-score of both the LV end-diastolic diameter (Zd) (r=0.698, P<0.0001) and LV end-systolic diameter (r=0.593, P<0.0001). Regression analysis and curve-fitting were used to predict the cQp/Qs based on the Zd, and a significant regression equation was found on cubic regression (R2of 0.524, P<0.0001) showing a strong correlation with the cQp/Qs (r=0.724, P<0.0001). CONCLUSIONS: The Z-score of the LV diameter can be a useful, non-invasive marker for evaluating LV volume overload and determining the surgical indications in children with VSD or PDA because of its strong correlation with the cQp/Qs.

Genetic and Cellular Interaction During Cardiovascular Development Implicated in Congenital Heart Diseases.

Congenital heart disease (CHD) is the most common life-threatening congenital anomaly. CHD occurs due to defects in cardiovascular development, and the majority of CHDs are caused by a multifactorial inheritance mechanism, which refers to the interaction between genetic and environmental factors. During embryogenesis, the cardiovascular system is derived from at least four distinct cell lineages: the first heart field, second heart field, cardiac neural crest, and proepicardial organ. Understanding the genes involved in each lineage is essential to uncover the genomic architecture of CHD. Therefore, we provide an overview of recent research progress using animal models and mutation analyses to better understand the molecular mechanisms and pathways linking cardiovascular development and CHD. For example, we highlight our recent work on genes encoding three isoforms of inositol 1,4,5-trisphosphate receptors (IP3R1, 2, and 3) that regulate various vital and developmental processes, which have genetic redundancy during cardiovascular development. Specifically, IP3R1 and 2 have redundant roles in the atrioventricular cushion derived from the first heart field lineage, whereas IP3R1 and 3 exhibit redundancy in the right ventricle and the outflow tract derived from the second heart field lineage, respectively. Moreover, 22q11.2 deletion syndrome (22q11DS) is highly associated with CHD involving the outflow tract, characterized by defects of the cardiac neural crest lineage. However, our studies have shown that TBX1, a major genetic determinant of 22q11DS, was not expressed in the cardiac neural crest but rather in the second heart field, suggesting the importance of the cellular interaction between the cardiac neural crest and the second heart field. Comprehensive genetic analysis using the Japanese genome bank of CHD and mouse models revealed that a molecular regulatory network involving GATA6, FOXC1/2, TBX1, SEMA3C, and FGF8 was essential for reciprocal signaling between the cardiac neural crest and the second heart field during cardiovascular development. Elucidation of the genomic architecture of CHD using induced pluripotent stem cells and next-generation sequencing technology, in addition to genetically modified animal models and human mutation analyses, would facilitate the development of regenerative medicine and/or preventive medicine for CHD in the near future.

Secondary Pseudohypoaldosteronism Associated With Mild Hydronephrosis in a Newborn.

Neonatal hyponatremia with hyperkalemia is a rare but potentially life-threatening occurrence. Aldosterone deficiency secondary to congenital adrenal hyperplasia (CAH) is often suspected in these cases, although it is not easy to accurately diagnose it initially. We report the case of a 12-day-old female infant presenting with poor sucking, hyperkalemia, and hyponatremia. Plasma renin activity (PRA) and aldosterone levels were markedly elevated, and mild hydronephrosis [Society for Fetal Urology (SFU) grade 1] was noted. We then suspected secondary pseudohypoaldosteronism (S-PHA); however, her serum potassium level remained elevated despite sodium infusion. Because we could not rule out a diagnosis of adrenal insufficiency caused by CAH, we cautiously initiated hydrocortisone. After reviewing the results of a mass screening test and a urine steroid profile analysis, adrenal diseases were ruled out and we diagnosed the patient with S-PHA. This report aims to illustrate that mild hydronephrosis can cause S-PHA by inducing renal tubular resistance to aldosterone. Because the symptoms of S-PHA are similar to those of CAH, we recognize that further studies are needed to clarify their differences.

Progressive cerebral and coronary aneurysms in the original two patients with Kosaki overgrowth syndrome.

Skeletal overgrowth accompanied by de novo heterozygous activating mutations in PDGFRB (platelet-derived growth factor receptor beta), that is, p.Pro584Arg and p.Trp566Arg, defines Kosaki overgrowth syndrome (OMIM #616592). Emerging evidence suggests a role of PDGFRB in the genesis of cerebral aneurysms. The delineation of the range and progression of the vascular phenotype of Kosaki overgrowth syndrome is urgently needed. Herein, we conducted subsequent analyses of serial neurovascular imaging studies of two original patients with a de novo heterozygous mutation in PDGFRB, that is, p.Pro584Arg. The analysis showed the progressive dilation of basilar and vertebral arteries and coronary arteries commencing during the teenage years and early 20s. The radiographic appearance of the basilar vertebral aneurysms showed signs of arterial wall dilation, compatible with the known vascular pathology of vascular-type Ehlers-Danlos syndrome and Loeys-Dietz syndrome. The dolichoectasia in cerebrovascular arteries can lead to fatal complications, even with neurosurgical interventions. To prevent the progression of artery dilation, preventative and therapeutic medical measures using tyrosine kinase inhibitors may be necessary in addition to optimal control of the systemic blood pressure. Kosaki overgrowth syndrome is a clinically recognizable syndrome that can exhibit progressive dilatory and tortuous vascular changes in basilar/vertebral and coronary arteries as early as in the teenage years. We recommend careful counseling regarding the risk of future vascular complications, optimal blood pressure control, and regular systemic vascular screening during follow-up examinations.

Inositol 1,4,5-trisphosphate receptor 2 as a novel marker of vasculature to delineate processes of cardiopulmonary development.

Congenital heart diseases (CHDs) involving the outflow tract (OFT), such as persistent truncus arteriosus (PTA), lead to mortality and morbidity with implications not only in the heart, but also in the pulmonary vasculature. The mechanisms of pulmonary artery (PA) development and the etiologies underlying PA disorders associated with CHD remain poorly understood partly because of a specific marker for PA development is nonexistent. The three subtypes of inositol 1,4,5-trisphosphate receptors (IP3R1, 2, and 3) are intracellular Ca2+ channels that are essential for many tissues and organs. We discovered that IP3R2 was expressed in the vasculature and heart during development using transgenic mice, in which a LacZ marker gene was knocked into the IP3R2 locus. Whole-mount and section LacZ staining showed that IP3R2-LacZ-positive cells were detectable exclusively in the smooth muscle cells, or tunica media, of PA, merging into αSMA-positive cells during development. Furthermore, our analyses suggested that IP3R2-LacZ positive PA smooth muscle layers gradually elongate from the central PA to the peripheral PAs from E13.5 to E18.5, supporting the distal angiogenesis theory for the development of PA, whereas IP3R2-LacZ was rarely expressed in smooth muscle cells in the pulmonary trunk. Crossing IP3R-LacZ mice with mice hypomorphic for Tbx1 alleles revealed that PTA of Tbx1 mutants may result from agenesis or hypoplasia of the pulmonary trunk; thus, the left and right central to peripheral PAs connect directly to the dorsal side of the truncus arteriosus in these mutants. Additionally, we found hypercellular interstitial mesenchyme and delayed maturation of the lung endoderm in the Tbx1 mutant lungs. Our study identifies IP3R2 as a novel marker for clear visualization of PA during development and can be utilized for studying cardiopulmonary development and disease.